detailed design report

T H E U N I V E R S I T Y O F S A L F O R D S C H O O L O F C O M P U T I N G , S C I E N C E A N D

E N G I N E E R I N G .

LEVEL 6 INTEGRATED DESIGN EXERCISE

SALFORD URBAN AIRPORT

DETAILED DESIGN REPORT

Prepared By:

Group 601: Ari Aziz Abubaker

Dilawar Ali Sam Cherrington

Asna Hassan

24/04/15

Group 601 Detailed Design Report

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Contents

Contents .......................................................................................................................................... ii List of Figures .................................................................................................................................. iv List of Tables .................................................................................................................................. vii The Brief ............................................................................................................................................ 8 Structures ......................................................................................................................................... 9

Introduction ................................................................................................................................ 9 Terminal Building ....................................................................................................................... 9

LinPro Results ........................................................................................................................ 10 Stability System .................................................................................................................... 12 Coursework Requirement ................................................................................................ 12 AutoCAD Drawings ............................................................................................................ 31

Aircraft Hangar ........................................................................................................................ 34 LinPro Results ........................................................................................................................ 41 ANSYS Results ....................................................................................................................... 42 Results .................................................................................................................................... 45 Foundation Design ............................................................................................................. 47

Structural Sketches ................................................................................................................. 51 FE and Seismic Engineering ...................................................................................................... 55

Structural Steelwork Design to EC3 .................................................................................... 55 Purlin Design ......................................................................................................................... 91

Stability System ........................................................................................................................ 92 AutoCAD Drawings ................................................................................................................ 96 Seismic Appraisal of Structure ........................................................................................... 103

Modal Analysis .................................................................................................................. 103 Seismic Lateral Force ....................................................................................................... 111

Conclusion .............................................................................................................................. 114 Construction Sequence .......................................................................................................... 115

Terminal Building ................................................................................................................... 115 Airport Hangar ....................................................................................................................... 123

Geotechnical Engineering ..................................................................................................... 130 Introduction ............................................................................................................................ 130 Foundation Design ............................................................................................................... 130 Linear Elastic Analysis ........................................................................................................... 142 Geotechnical Finite Element Analysis ............................................................................. 144 Conclusion .............................................................................................................................. 152 Base Heave ............................................................................................................................ 153

Transportation ............................................................................................................................ 156 Introduction ............................................................................................................................ 156 Traffic Control Devices ........................................................................................................ 157

Signage ............................................................................................................................... 157 Traffic Floor Markings ....................................................................................................... 158

Airport Road Design ............................................................................................................. 161 Airport Car Park Design ....................................................................................................... 165 Airport Runway Design ........................................................................................................ 165 Maintenance of Flexible Pavements .............................................................................. 177 Sustainability Considerations for Constructing Flexible Pavements ....................... 179 Noise Reduction Methods .................................................................................................. 181


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Runway Safety System ........................................................................................................ 183 Runway Drainage ................................................................................................................. 184

Design Procedure ............................................................................................................. 185 T-Junction Design .................................................................................................................. 185

Water Resources ....................................................................................................................... 189 Surface Water Drainage System ...................................................................................... 189

Pipe Design ........................................................................................................................ 189 Water Supply System ........................................................................................................... 192

Design Calculation .......................................................................................................... 193 Pipe Design ........................................................................................................................ 194

Flooding ................................................................................................................................... 196 Design Foul Sewer ................................................................................................................. 199 Design Consideration .......................................................................................................... 199

Traps ..................................................................................................................................... 199 Discharge Pipe Design ........................................................................................................ 200 Design Discharge Stacks .................................................................................................... 200 Pumping Installation ............................................................................................................. 201

Material for Pipes and Joints ......................................................................................... 201 Sustainability ...................................................................................................................... 201

Attenuation Tank Specification ........................................................................................ 202 Critique ......................................................................................................................................... 204 Conclusion .................................................................................................................................. 205

HEC-RAS Coursework ........................................................................................................... 206 Appendix A – Health and Safety .......................................................................................... 278


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List of Figures

Figure 1: Terminal building arrangement in LinPro ................................................ 10

Figure 2: Bending moment envelope for terminal building ............................... 11

Figure 3: Axial force envelope for terminal building ............................................ 11

Figure 4: Deflection diagram for terminal building ............................................... 11

Figure 5: Bending moment envelope for portal frame ....................................... 41

Figure 6: Shear force diagram for portal frame .................................................... 41

Figure 7: Axial force diagram for portal frame ...................................................... 42

Figure 8: Reactions for portal frame ......................................................................... 42

Figure 9: Bending moment envelope produced in ANSYS ................................ 43

Figure 10: Shear force envelope produced in ANSYS ......................................... 44

Figure 11: Axial force envelope produced in ANSYS ........................................... 45

Figure 12: Structural displacement in ANSYS .......................................................... 46

Figure 13: Bending moment diagram for 36m span ............................................ 91

Figure 14: Deflection diagram for 36m span .......................................................... 91

Figure 15: Diagonal bracing arrangement ............................................................. 92

Figure 16: Axial force diagram for bracing system ............................................... 93

Figure 17: Bending moment diagram for bracing system .................................. 93

Figure 18: Mass arrangement in LinPro ................................................................... 104

Figure 19: Input of mass in LinPro ............................................................................. 104

Figure 20: Natural frequencies output in LinPro ................................................... 104

Figure 21: Structural sway caused by fundamental natural frequency ....... 105

Figure 22: Element data input to ANSYS ................................................................ 105

Figure 23: Material properties input to ANSYS ...................................................... 106

Figure 24: Boundary conditions input to ANSYS ................................................... 106

Figure 25: Natural frequencies results in ANSYS ................................................... 106

Figure 26: Deformed shaped caused by fundamental natural frequency in ANSYS ............................................................................................................................... 107

Figure 27: Effective mass calculated in ANSYS .................................................... 107

Figure 28: Horizontal elastic response spectra ..................................................... 111

Figure 29: Seismic load combination used in static analysis ............................ 112

Figure 30: Lateral seismic load input to LinPro ..................................................... 112

Figure 31: Bending moment diagram from seismic load combination ........ 112

Figure 32: Shear force diagram from seismic load combination ................... 113

Figure 33: Axial force diagram from seismic load combination ..................... 113

Figure 34: Construction sequence: Stage 1 ......................................................... 115



Figure 37: Unloading of structural steel .................................................................. 117

Figure 38: Temporary works cofferdam supporting basement excavation 118

Figure 39: Construction of basement floor slab in cofferdam......................... 118



Figure 42: Steelwork erection .................................................................................... 120

Figure 43 Construction sequence: Stage 6 ........................................................... 121


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Figure 45: Surveying of site and setting out .......................................................... 123

Figure 46: Excavation for pad foundation ............................................................ 124

Figure 47: Construction of concrete pad foundation ....................................... 125

Figure 48: Erection of steel portal frame ................................................................ 126

Figure 49: Completion of steel erection ................................................................ 127

Figure 50: Installation of purlins and cross bracing ............................................. 128

Figure 51: Installation of cladding and internal services ................................... 129

Figure 52: Modes of bearing capacity of failure of soil. (a) General shear failure; (b) local shear failure (Terzaghi, 1943) ..................................................... 131

Figure 53: Beam-spring model created in LinPro ................................................ 142

Figure 54: Shear force diagram for beam-spring model .................................. 143

Figure 55: Bending moment diagram for beam-spring model ....................... 143

Figure 56: Bending moment diagram for effective stress conditions ............ 144

Figure 57: Soil types input to Plaxis ........................................................................... 145

Figure 58: Soil parameters input to Plaxis ............................................................... 146

Figure 59: Generated soil mesh in Plaxis ................................................................ 147

Figure 60: Soil deformation caused for pad foundation .................................. 147

Figure 61: Soil deformation caused by erection of portal frame ................... 147

Figure 62: Long term soil deformation .................................................................... 148

Figure 63: Location of maximum soil displacement in Plaxis ........................... 148

Figure 64: Soil displacement caused by pad foundation ................................ 149

Figure 65: Soil displacement caused by portal frame ....................................... 149

Figure 66: Soil displacement during long term conditions ................................ 150

Figure 67: Maximum soil settlement beneath pad foundation ...................... 150

Figure 68: Long term soil displacement showing heave ................................... 150

Figure 69: Bending moment envelope for pad foundation in Plaxis ............. 151

Figure 70: Shear force envelope for pad foundation in Plaxis ........................ 151

Figure 71: Airport concept highlights roads and carpark ................................ 156

Figure 72: Main link roads to airport site ................................................................. 157

Figure 73: Entrance and exit airport site roads .................................................... 158

Figure 74: Airport floor marking layout example (Flight learnings, n.d.) ....... 160

Figure 75: General features of a heliport (Federal Aviation Administration, 2012) ................................................................................................................................. 160

Figure 76: Minimum percentage of OGV2 vehicles ........................................... 162

Figure 77: Wear factors for the design vehicle types ......................................... 162

Figure 78: Growth factors for design vehicle types ............................................ 163

Figure 79: Percentage of vehicles in heaviest traffic lane ............................... 163

Figure 80: Design flexible surface thicknesses for site road .............................. 164

Figure 81: Capping layer and sub-base thicknesses ......................................... 164

Figure 82: Capping layer and sub-base thicknesses ......................................... 165

Figure 83: ACN for design aircraft ........................................................................... 166

Figure 84: Number of coverages for design aircraft .......................................... 166

Figure 85: Runway surface type for design aircraft and trafficking frequency ........................................................................................................................................... 167

Figure 86: Flexible pavement patching procedure (Transport 1994) ............ 178

Figure 87: Secondary and recyclable waste material (Transport, 2004) .... 181


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Figure 88: Constructed noise barrier location on site ........................................ 182

Figure 89: Runway end safety precaution ............................................................ 184

Figure 90: Requisition quotation service levels and flow chart (United Utilities, 2012) ................................................................................................................................. 192

Figure 91: Framework for undertaking a SWMP study (Defra, 2010) .............. 197

Figure 92: Location of attenuation tank on site ................................................... 202


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List of Tables

Table 1: Eurocode load combinations ..................................................................... 10

Table 2: Eurocode partial factors .............................................................................. 10

Table 3: Steel section performance for terminal building .................................. 12

Table 4: Eurocode partial factors for airport hangar ........................................... 35

Table 5: Eurocode partial factors .............................................................................. 35

Table 6: Maximum forces on portal frame .............................................................. 45

Table 7: Steel member performance subject to flexure ................................... 114

Table 8: Steel member performance subject to axial force ........................... 114

Table 9: Steel member performance subject to shear force .......................... 114

Table 10: Eurocode 7 partial factors ....................................................................... 133

Table 11: Eurocode 7 partial factors for soil parameters .................................. 133

Table 12: Modulus of subgrade reaction for cohesive soil (Bowles, 1997) .. 142

Table 13: Results table for the three methods of analysis ................................. 152

Table 14: Site road pavement thicknesses ............................................................ 176

Table 15: Car Park pavement thicknesses ............................................................ 176

Table 16: Airport runway pavement thicknesses ................................................ 176

Table 17: Minimum trap sizes and seal depths .................................................... 199

Table 18: Common branch discharge pipe (unventilated) ............................ 200

Table 19: Storm water attenuation tank typical specification (Anuainternational.com, 2015) ................................................................................ 203


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The Brief

A detailed analysis of the selected scheme is explained throughout the design and final report. This report is a continuation of semester one’s feasibility study however with more calculations and one specific chosen scheme. The feasibility report included a lot of research whereas this report includes detailed design calculations, general arrangement drawings, bill of quantities and a tender document for the chosen recommended scheme. Our group had to design an airport that included two structures, which were the terminal building and the aircraft hangar. However for this report, it was necessary to design one structure, which we all agreed to design the aircraft hangar. The main aim is to classify all the critical elements for this design. It is also required to include design hand calculations, detailed construction sequence and software analysis.

One scheme was chosen from the three schemes produced in the feasibility report however with more detailed analysis. For the structural engineering aspect of this report the wind loading, dead, imposed loading on the structure were determined. Once that was completed, it was inputted into ANSYS as well as LinPro model software and was compared with the hand calculations. Another feature was to determine the stability system for structure as well as the justification. The critical elements such as beams, columns and purlins were calculated according to the EC3. Once it’s been completed, the maximum bending moment, shear, axial and deflection is determined. Sketches are included in this report to design the structural behaviour and load pathway. AutoCAD drawings are included to design the structure and connection details such as base plate, beam-column.

For the transportation engineering aspect for this report, a construction sequence was created for the runway, car park and the airport road alongside the method statements with construction sequence. Sustainability related to the highway design and safe barriers at the end of the runway for safety were discussed in this report.

For geotechnical engineering aspects for this design detail included hand calculation for the selected foundation with a complete PLAXIS analysis foundation to analyse settlement and complete AutoCAD drawings for foundation details with full reinforcement design according to EC2 for foundation.

Finally, for water resource engineering aspect for this detail design included detailed estimation for water demand for the site, to estimate the requirement of water for fire-flow demand, to design water supply system for the site and to design surface water drainage network for the site alongside methods for creating a plan that is environmental friendly.


9

Structures

Introduction

As part of the integrated design exercise it is a requirement to progress from the feasibility report submitted in semester 1. The structures module for the feasibility report included choosing three different design concepts for the airport hangar which will be located on the airport site. The final design report requires one concept to be chosen from the feasibility report and progressed in semester 2.

However, the airport will consist of two main structures; the airport hangar and terminal building. During semester 2 the airport hangar will be designed in full using a number of computer software to analyse the structural behaviour and to aid in calculating the structural forces in each member. In addition, as the terminal building is an important aspect of the airport site, basic design calculations will be undertaken including a suitable stability system and steel element design.

Terminal Building The terminal building will have a building envelope of 2160m² as the length of the building will be 72m with a width of 30m. It was a requirement of the client to have a maximum building height of 8m therefore the airport terminal building has been designed to contain a large building envelope and two floors. In addition, the terminal building will comprise of a basement which will be used for staff and contain a plant room for building services. Prior to completing the structural analysis, the wind pressure acting onto the structure was calculated. As the terminal building will consist of a mono-pitched roof this was considered when calculating the wind pressure and wind suction coefficients. The wind pressure and wind suction acting onto the terminal building walls and roof was calculated utilising ‘Eurocode 1: Actions on Structures’. In addition to wind pressure, the permanent floor action and variable floor action was calculated. The classification of the building was used to determine a suitable value for the imposed floor action (5kN/m²) (Cobb, 2004). The permanent floor load was determined by calculating the dead weight of the composite floor slabs in addition to steel beams. The permanent floor load was calculated as 3.3kN/m². The software LinPro was used to calculate the maximum structural forces in the structure. LinPro was used to input a number of load cases and load combinations which allowed the design team to input the partial load


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factors derived from Eurocode 1 equation 6.10, 6.10a, and 6.10b. The load combinations considered have been shown in Table 1. Table 1: Eurocode load combinations

Load Type Partial Safety Factors

6.10 (i) 1.35Gk + 1.50Qk

6.10 (ii) 1.35Gk + 1.50Qk + (0.50x1.50Wk)

6.10 (iii) 1.35Gk + (0.70x1.50Qk) + (1.50Wk)

6.10a (i) 1.35Gk + (0.70x1.50Qk) + (0.50x1.50Wk)

6.10b (ii) (0.925x1.35Gk) + 1.50Qk + (0.50x1.50Wk)

Table 2: Eurocode partial factors


Dead Load 1.35

Live Load 1.50

Wind Load (Pressure) 1.50

The terminal building was to consist of a rigid steel frame constructed using the following steel sections:

Column size: 305x305x137UC (S275) Floor beam size: 457x191x74UB (S275) Roof beam size: 356x171x67UB (S275)

The internal columns where spaced at a distance of 6.0m as the floor loading was anticipated to be high thus reducing the bending moment in the floor beams and roof beams. As there was an 8.0m height restriction it was important that the depth of the floor beam did not greatly reduce the clearance height of each floor. The steel columns where anchored onto the concrete foundation using a fixed connection. The column and beams where connected using a rigid moment connection. The internal structure was inputted onto LinPro (Figure 1) and the anticipated load cases where inputted. The load case that produced the greater axial force and bending moment in the steel elements was Eurocode equation 6.10 (ii), shown in Table 2.

Figure 1: Terminal building arrangement in LinPro

LinPro Results The bending moment envelope was plotted using LinPro (Figure 2) and was used to calculate the maximum anticipated flexure in the roof and floor beams. The maximum moment on the column was recorded and this would be used to check the combined axial and bending on the column.


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Figure 2: Bending moment envelope for terminal building

The maximum calculated bending moment included:

Maximum bending moment in floor beam: 236.48kNm Maximum bending moment in roof beam: 164.40kNm Maximum bending moment in column: 110.13kNm

Figure 3: Axial force envelope for terminal building

The maximum calculated axial force included:

Maximum axial force in floor beam: 12.8kN Maximum axial force in roof beam: 42.74kN Maximum axial force in column: 747.96kN

Figure 4: Deflection diagram for terminal building

The maximum calculated deflection for each structural member included:

Maximum deflection in floor beam: 5.45mm Maximum deflection in roof beam: 6.07mm

The maximum deflection of the steel beams where less than the maximum deflection therefore the results where adequate. The steel elements where designed to EC3 using the maximum forces observed in LinPro. The performance of each steel member has been recorded in Table 3.


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Table 3: Steel section performance for terminal building

Maximum Moment

(kNm)

Allowable Moment

(kNm)

Pass/Fail Maximum Axial Load

(kN)

Allowable Axial Load

(kN)

Pass/Fail

Roof Beam 164.40 205.90 Pass 42.74 n/a Pass

Floor Beam 236.48 268.40 Pass 12.80 n/a Pass

4.0m Column 110.13 746.00 Pass 747.96 4567.00 Pass

It is clear from Table 3 that each steel member was satisfactory for the rigid frame. The steel member utilisation was adequate for the roof beam (79%) and floor beam (88%). From the hand calculations it was clear that the steel column was only utilised by 32%. However, this section size was chosen as it was connected to a steel beam which contained a larger depth. The design team decided that a smaller steel column may have been utilised however, if the building was to suffer from an accidental load it would be likely that a smaller steel section would collapse first. Therefore, by increasing the size of the column it would ensure that the steel beam would be first to collapse.

Stability System The terminal building stability system has been designed to incorporate reinforced concrete shear walls located on two sides of the structure. The shear walls will provide stability against wind force. The horizontal steel beams where connected to the shear walls by a fixed connection using anchor bolts. The shear wall was designed using hand calculations to determine the steel reinforcement requirement.

Coursework Requirement

As the design group was required to focus solely on 1 chosen scheme to satisfy the Structures requirement, the structural design work for the terminal building will not be continued. The design group will now complete the full design for the airport hangar including steelwork and concrete foundations.


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AutoCAD Drawings The following pages include a number of AutoCAD drawings to accompany the terminal building design concept.


34

Aircraft Hangar It was a requirement for the airport to contain a hangar to allow aircraft to be parked when not in use. Furthermore, a hangar would provide staff with the facilities to fix and repair aircraft when required, protected from the elements. In regards to the clients briefing the airport hangar would be no greater than 8.0m high and would accommodate small craft carrying no more than 3 persons at one time. Therefore, after conducting extensive research into the dimensions of small aircraft and hangars the design team decided that an envelope 36.0m x 30.0m was suitable. The Feasibility study, submitted in semester 1, required the design team to submit three design concepts for the airport hangar. The design team proposed three different ideas including:

Steel portal frame with pitched roof Steel rigid frame with roof truss Steel three pinned arch supported by RC thrust block.

The design team decided that the concept which would be continued to full detailed design was the steel portal frame with pitched roof. The portal frame would comprise of a steel columns connected to steel rafters which would be spaced at 6.0m intervals. The chosen 6.0m spacing was determined using trial and error as larger column spacing would produce greater loads onto the frame, thus requiring larger members. It was agreed in the Geotechnical Engineering chapter that the most appropriate foundation was a reinforced pad foundation beneath each steel column. The portal frame would contain cross bracing at opposite ends of the structure to stabilise the structure. Steel purlins and cladding would be used to form the building exterior. Furthermore, each column was design to connect to the foundation as a pin connection. Subsequently, this produced no moment at the pin connection allowing for concentric loading on the pad foundation. The preliminary steel section sizes for the portal frame included:

Steel column: 610x229x101UB (S275) Steel rafter: 533x210x109UB (S275)

In order to determine the maximum forces in the structure a 2D linear elastic model was produced in LinPro. The results of the static analysis, conducted in LinPro, where compared against a 3D finite element analysis using ANSYS. ANSYS provided the design team with a validation tool and a method to assess the structural stability of the portal frame, under wind loading. Furthermore, both methods of analysis where used to perform a seismic assessment for the structure using the specified EC8 response spectra.


35

The load combinations considered for the aircraft hangar design where shown in Table 4. Furthermore, the Eurocode partial factors where included in Table 5. As the hangar consisted of a 30m spanning roof, comprised of steel rafters, it was necessary to include a load case for wind suction. Each load case and load combination was input to LinPro. The most onerous load case was deemed 6.10(i). Therefore the structural forces in this load case where recorded and where compared against the ANSYS results. Table 4: Eurocode partial factors for airport hangar

Load Type Load Combinations

6.10 (i) 1.35Gk + 1.50Qk

6.10 (ii) 1.35Gk + 1.50Qk + (0.50x1.50Wk)

6.10 (iii) 1.35Gk + (0.70x1.50Qk) + (1.50Wk)

6.10a (i) 1.35Gk + (0.70x1.50Qk) + (0.50x1.50Wk)

6.10b (ii) (0.925x1.35Gk) + 1.50Qk + (0.50x1.50Wk)

Wind Suction 1.35Gk + 1.50Wsuction

Table 5: Eurocode partial factors


Dead Load 1.35

Live Load 1.50

Wind Load (Pressure) 1.50

Wind Load (Suction) 1.50

The following pages include the process used to determine the loading acting onto the portal frame. The anticipated wind load on the structure was determined using Eurocode 1. The wind load pressure and suction was determined due as the size of the structure. It was anticipated that high wind suction pressures would act onto the long spanning roof. The dead load and live load acting onto the rafters has also been determined.


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LinPro Results

The portal frame model was designed as pinned column-base connection thus making the structure statically indeterminate. The model was input to LinPro with a rigid connection at the apex of the roof. This produced flexure in the rafter connection which must be considered when completed the steelwork design. It may be necessary to include an apex haunch as this will maximise the size of the level arm in order to reduce the compressive force in the rafters, caused by bending moment. A haunch may also be utilised at the location between column and rafter as bending moment will be greatest at this point.

Figure 5: Bending moment envelope for portal frame

The maximum bending moment in the frame included:

Steel column (stanchions): 544.9kNm Steel rafter: 544.9kNm At apex haunch: 325.0kNm

Figure 6: Shear force diagram for portal frame

The maximum observed shear force in the frame included:

Steel column: 81.3kN Steel rafter: 122.6kN


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Figure 7: Axial force diagram for portal frame

The maximum axial force in the structure included:

Steel column: 130.1kN Steel rafter: 92.3kN

Figure 8: Reactions for portal frame

ANSYS Results

The structural model was re-created in ANSYS in order to validate the calculated forces in LinPro. Furthermore, as LinPro was unable to calculate effective mass, ANSYS was required to complete a seismic assessment. The structural model needed to be seismically assessed before starting the EC3 steelwork design, to ensure the chosen structural members where suitable.

The aircraft hangar was designed as a portal frame and contained a building envelope of 36m x 30m. Therefore, internal columns where spaced at 6.0m. The column spacing was determined using LinPro to ensure that the anticipated loading was acceptable to the structure. Therefore, two ANSYS models where created. The first ANSYS model consisted of a 2D arrangement which was created to validate the static analysis completed in LinPro. The second ANSYS model included a 3D representation of the aircraft hangar. The 3D model was used to analyse the performance of the hangar stability system and to investigate the 3D structural behaviour. The 3D model consisted of columns, rafters, and purlins. The steel purlins would be designed to resist the anticipated lateral loading imposed by wind. The


43

nodes where positioned at 0.50m centres along structural members. The co-ordinate locations for the rafters where determined using AutoCAD.

The most onerous load combination determined in LinPro was used in ANSYS to obtain the maximum forces on the structure. Therefore, load combination 6.10(i) (Table 4) was utilised. The factored vertical load input to ANSYS was 8.64kN. As ANSYS analysed in Newton’s, a uniform pressure of 8640N was applied to the rafters.

Figure 9 illustrates the bending moment diagram for the portal frame in ANSYS. In order to produce the bending moment diagram a static analysis was performed and an elements table was defined. The bending moment diagram was produced using the input SMIS6 (node I) and SMIS12 (node J). A scale factor of -1 was applied to ensure that the bending moment diagram had the correct scale. Figure 9 indicated that the maximum bending moment results in the steel column and rafter was very similar to LinPro.

Figure 9: Bending moment envelope produced in ANSYS

The maximum bending moment in the frame included:

Steel column (stanchions): 540.80kNm Steel rafter: 540.80kNm At apex haunch: 322.61kNm


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Figure 10 illustrates the shear force diagram produced in ANSYS. The defined elements table used to produce the shear force diagram included SMIS2 (node I) and SMIS8 (node 8).

Figure 10: Shear force envelope produced in ANSYS

The maximum observed shear force in the frame included:

Steel column: 80.72kN Steel rafter: 124.53kN Apex haunch: 7.0kN

Figure 11 displays the axial force diagram for the portal frame in ANSYS. In order to create the axial force diagram an elements table was produced using SMIS1 (node I) and SMIS7 (node J).


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Figure 11: Axial force envelope produced in ANSYS

The maximum axial force in the structure included:


Results

The results of the static analysis in ANSYS are clearly similar to the forces obtained through the static analysis in LinPro. Therefore, the ANSYS model was deemed suitable to utilise when performing a modal analysis. The maximum anticipated forces on the structure was shown in Table 6, considering the worst case results from both sets of analysis. The maximum forces from the static analysis will be compared against the forces obtained through the seismic assessment. The worst case forces will then be used to perform a Eurocode 3 steelwork design for all members.

Table 6: Maximum forces on portal frame

Maximum Moment

(kNm)

Maximum Axial Force

(kN)

Maximum Shear

Force (kN)

Column 544.9 130.0 82.0

Rafter 544.9 93.0 123.0

Apex Haunch 325.0 93.0 7.0


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Figure 12 shows the initial deflection in the roof was recorded as 0.166m (166mm). (Cobb, 2009) suggested that a vertical deflection limit of span/250 should be used for the roof. As the roof contained a 30m span the maximum deflection limit was calculated as 120mm. This was deemed greater than the allowable and as such the preliminary steel rafter size may need to be addressed to reduce deflection. This issue will be investigated in the steelwork design section of this document. It was noted that the introduction of a haunch between rafter and column may reduce the total deflection in the roof. This will need to be investigated further.

Figure 12: Structural displacement in ANSYS


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Foundation Design

The airport hangar will be founded on a pad foundation. Due to the internal spacing of columns and maximum axial load, a pad foundation was deemed the most appropriate type of footing. The size of the pad foundation has been included in this Geotechnical engineering chapter within this document. The pad foundation dimensions where validated with hand calculations and a geotechnical finite element analysis.

The reinforced concrete design has been included within this part of the document as it fulfils the requirement for the Structures module. The following pages include the hand calculations used to perform the foundation design to EC2. A generic pad foundation design was included to support each column of the portal frame.


51

Structural Sketches

The following pages have been included to show sketches of the structural concept. The sketches include the load pathway through the structure and the locations of wind bracing in the structure. As the structure envelope will be 36m x 30m it will be appropriate to brace two identical bays at opposite ends of the structure.


55

FE and Seismic Engineering

Structural Steelwork Design to EC3 The following pages include the hand calculations used to design the steel portal frame to Eurocode 3. The hand calculations include the design of the column and rafter in addition to the steel purlin. In order to design the purlin, Steadmans specification brochures where used. The purlin rails, & eaves beam load brochure and load tables where used to determine a suitable purlin, using anticipated moment. To complete the steelwork design the column- pad foundation base plate and anchor bolt connection was completed. As the design considered the column as pinned, a nominally pin connection was provided in the form of 4 anchor bolts into the pad foundation. A stability system was then design using a wind bracing system. The type of wind bracing was determined using the maximum anticipated wind forces, on both windward and leeward faces of the structure. The stability system design completed the steelwork requirement. A seismic assessment was then performed on the structure to observe its behaviour during a seismic event.

Sam

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Input data and results must be checked for agreement with the existing conditions and for plausibility!PROFIS Anchor ( c ) 2003-2009 Hilti AG, FL-9494 Schaan Hilti is a registered Trademark of Hilti AG, Schaan

Company:Specifier:Address:Phone I Fax:E-Mail:

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Page:Project:Sub-Project I Pos. No.:Date:

1

19/04/2015

Specifier's comments:

1 Input dataAnchor type and diameter: HIT-HY 200-A + HIT-V (5.8) M16Dynamic set or any suitable annular gap filling solutionEffective embedment depth: hef,act = 120 mm (hef,limit = - mm)

Material: 5.8

Evaluation Service Report: ETA 11/0493

Issued I Valid: 08/08/2012 | 23/12/2016

Proof: design method SOFA design method + fib (07/2011) - after ETAG BOND testing

Stand-off installation: eb = 0 mm (no stand-off); t = 20 mm

Anchor plate: lx x ly x t = 750 mm x 400 mm x 20 mm; (Recommended plate thickness: not calculated)

Profile: Advance UKB; (L x W x T x FT) = 603 mm x 228 mm x 15 mm x 15 mm

Base material: cracked concrete, C30/37, fc = 30.00 N/mm2; h = 500 mm, Temp. short/long: 0/0 °CInstallation: hammer drilled hole, installation condition: dry

Reinforcement: no reinforcement or reinforcement spacing >= 150 mm (any Ø) or >= 100 mm (Ø <= 10 mm)

no longitudinal edge reinforcement

Geometry [mm] & Loading [kN, kNm]

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www.hilti.co.uk Profis Anchor 2.4.9

Input data and results must be checked for agreement with the existing conditions and for plausibility!PROFIS Anchor ( c ) 2003-2009 Hilti AG, FL-9494 Schaan Hilti is a registered Trademark of Hilti AG, Schaan

Company:Specifier:Address:Phone I Fax:E-Mail:

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Page:Project:Sub-Project I Pos. No.:Date:

2

19/04/2015

2 Proof I Utilization (Governing Cases) Design values [kN] Utilization

Loading Proof Load Capacity bbbbN / bbbbV [%] Status Tension - - - - / - -

Shear Steel Strength (without lever arm) 20.250 31.200 - / 65 OK

Loading bbbbN bbbbV aaaa Utilization bbbbN,V [%] Status Combined tension and shear loads - - - - -

3 Warnings• Please consider all details and hints/warnings given in the detailed report!

Fastening meets the design criteria!4 Remarks; Your Cooperation Duties• Any and all information and data contained in the Software concern solely the use of Hilti products and are based on the principles, formulas

and security regulations in accordance with Hilti's technical directions and operating, mounting and assembly instructions, etc., that must be strictly complied with by the user. All figures contained therein are average figures, and therefore use-specific tests are to be conducted prior to using the relevant Hilti product. The results of the calculations carried out by means of the Software are based essentially on the data you put in. Therefore, you bear the sole responsibility for the absence of errors, the completeness and the relevance of the data to be put in by you. Moreover, you bear sole responsibility for having the results of the calculation checked and cleared by an expert, particularly with regard to compliance with applicable norms and permits, prior to using them for your specific facility. The Software serves only as an aid to interpret norms and permits without any guarantee as to the absence of errors, the correctness and the relevance of the results or suitability for a specific application.

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Purlin Design

A number of purlins where required to provide lateral restraint to the tension flange in both column and rafter. In addition, as rafter and columns are spaced at 6.0m centres, purlins provide flexural continuity between spans. The chosen purlins specification was a Z purlin manufactured by Steadmans.

The steel purlin was designed using the worst case load combination (6.10(i)). This imposed a maximum vertical load of 8.64kN/m onto the structure. It would be required for the purlin to span between rafters and column therefore the required length was 6.0m. Therefore, LinPro was used to perform a beam analysis on the full 36m span. Figure 13 illustrates the bending moment diagram for the beam analysis.

Figure 13: Bending moment diagram for 36m span

The maximum moment of the beam analysis was used to determine a suitable Z purlin size. The Z purlin was designed using the load tables provided by Steadmans, ensuring that the maximum allowable moment was greater than 32.90kNm. Figure 14 shows the deflection diagram from the beam analysis in LinPro. The maximum allowable deflection for the purlin was calculated using L/200 (Cobb, 2009). Therefore, the maximum allowable deflection was calculated as 30mm. LinPro indicated a maximum deflection of 22mm, therefore the deflection was deemed suitable.

Figure 14: Deflection diagram for 36m span


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Stability System

The airport hangar will be comprised of a steel portal frame consisting of columns and rafters. The steel columns will be spaced at 6.0m centres. In order to ensure that structure does not collapse a stability system was required. The stability system for a steel portal frame may have been designed using either bracing or shear walls. It is common for portal frames in the U.K to contain brick shear walls located on two opposing sides of a portal frame. However, a diagonal bracing system was chosen to provide the structure with stability. As the length of the structure was 36m it was necessary to brace two bays on both sides of the structure. Furthermore, the structure would contain permanent cladding on three sides of the structure where one side would be subject to a gate, allowing aircraft to enter and exit the hangar. Therefore, it was anticipated that wind suction would be present which in turn may cause damages to the roof cladding and steelwork. In order to reduce the effect of wind suction diagonal roof bracing was used.

The roof bracing would be located at two sections, at the same locations of the lateral wind bracing. Both roof and column bracing systems would comprise of diagonal cross bracing. The purpose of diagonal cross bracing was to allow a diagonal tension element to absorb the wind force and transfer the force to the column. The force would then be transferred through the column and into the pad foundation. The additional diagonal element was subject to compression and was expected to provide little resistance against wind load.

The bracing system between two columns was shown in Figure 15. The maximum anticipated wind pressure was input and the most onerous axial force was observed.

Figure 15: Diagonal bracing arrangement


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Figure 16 illustrates the axial force diagram for the bracing system subject to a lateral UDL. The maximum anticipated tensile force in the diagonal bracing was used to determine the section size. In addition, the specified column was input to LinPro with the necessary steel parameters.

Figure 16: Axial force diagram for bracing system

The bending moment diagram for the bracing system in shown in Figure 17. The maximum moment in the diagonal bracing was 3.88kNm. The maximum moment was deemed less than the allowable.

Figure 17: Bending moment diagram for bracing system


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AutoCAD Drawings The following pages include a number of AutoCAD drawings produced in order to support the structural scheme. The AutoCAD drawings where produced using the information obtained through hand calculations and computer software.


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Seismic Appraisal of Structure

Modal Analysis

A seismic analysis was performed on the portal frame to assess its performance during a seismic event. The seismic assessment was performed using a modal analysis in LinPro and ANSYS to determine the structures fundamental natural frequency. Furthermore, as the portal frame contain a single floor, Blevins was used to determine the fundamental natural frequency. The purpose of the modal analysis was to determine the seismic lateral force caused by a seismic event such as an earthquake. It was expected that the portal frame would suffer sway therefore the seismic assessment included horizontal action.

In order to determine the seismic lateral force, base shear was determined. As LinPro was unable to calculate base shear, ANSYS was used. The 2D model created in ANSYS was used to perform a modal analysis. Furthermore, it was deemed good practise to perform a modal analysis in ANSYS, as it validated the natural frequencies created in LinPro.

As the building was designed as a portal frame the natural frequency was determined for a SDOF system. Therefore, only one natural frequency would need to be determined for sway.

In order to determine the fundamental natural frequency in Blevins, LinPro and ANSYS the total mass acting on the portal frame roof needed to be calculated. The total mass was determined using the dead load and live load, in addition to the rafter weight. The total mass equalled 21620.8kg. In order to calculate the natural frequency in Blevins the following equation was used:

�� =�

��

��³�

�

� (Blevins, 1979)

Where:

��= Second moment of area (cm4)

The natural frequency for the SDOF system was calculated as 1.19Hz. This frequency was then compared against the natural frequency determined from a modal analysis in both LinPro and ANSYS.

The total mass was assigned in LinPro on nodes, ensuring mass was evenly distributed across the rafters. The rafters where comprised for 9 nodes, therefore mass was divided by 8 nodes thus ensuring 2.70kg was applied to internal nodes. The two nodes located at the location of columns where assigned half the mass given to an internal node i.e. 1.35kg. This was


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because mass was only present on one side of the node. Figure 18 illustrates the mass distribution on the portal frame in LinPro.

Figure 18: Mass arrangement in LinPro

Figure 19 presents how the magnitude of mass was applied to nodes in LinPro.

Figure 19: Input of mass in LinPro

Figure 20 shows the calculated natural frequencies in LinPro. As the structure was a SDOF system the fundamental natural frequency only produced sway. The fundamental natural frequency from the modal analysis was 0.943Hz.

Figure 20: Natural frequencies output in LinPro


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The deformed shape of the structure due to the fundamental natural frequency is shown in Figure 21. It is clear that the structure is subject to sway.

Figure 21: Structural sway caused by fundamental natural frequency

ANSYS was used to validate the natural frequency calculated in LinPro and to determine effective mass. The application of mass was input on elements. This was different from LinPro was mass was input on nodes. The mass was input in ANSYS per unit length therefore the total mass was divided by 30m i.e. 720.69kg. Figure 22 highlights how mass was applied in ANSYS.

Figure 22: Element data input to ANSYS

Figure 23 shows how the material properties where input to ANSYS, using the correct units.


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Figure 23: Material properties input to ANSYS

Figure 24 illustrates the completed structural model input to ANSYS. The structure was supported by a pin connection at the column bases therefore vertical and horizontal displacement was constrained.

Figure 24: Boundary conditions input to ANSYS

A modal analysis was performed in ANSYS in order to determine the fundamental natural frequency and effective mass. The fundamental natural frequency was calculated as 0.952Hz, shown in Figure 25.

Figure 25: Natural frequencies results in ANSYS

Figure 26 illustrated the deformed shape of the structure for the fundamental natural frequency 0.952Hz. The deformed shape caused by the natural frequency clearly shows the structure in sway. It was observed that the deformed shape was similar to the result in LinPro.


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Figure 26: Deformed shaped caused by fundamental natural frequency in ANSYS

The total effective mass was determined in ANSYS for the three natural frequencies. As the fundamental natural frequency was 0.95Hz the effective mass was deemed 20712.0kg. The effective mass was used to determine the base shear force.

Figure 27: Effective mass calculated in ANSYS

The following pages show the process used to determine the lateral seismic force acting on the structure. The first stage included the determination of natural frequencies followed by the calculation of base shear. As the portal frame was one storey the value for base shear equalled the lateral seismic force.


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Seismic Lateral Force In order to perform a seismic assessment of the portal frame the lateral seismic force was applied to the structure and a static analysis was performed. The lateral seismic force was determined using base shear. As the portal frame consisted of one storey, the base shear was calculated using the peak ground acceleration and effective mass. The base shear was determined on the previous pages. A horizontal response spectrum was produced, shown in Figure 28, to determine the peak ground acceleration for the structure. Eurocode 8 included the necessary formulae needed to complete the response spectrum. The formulae included:

0 ≤ � ≤ ��: ��(�) = �� 1 +�

��(2.5� − 1)� (Fardis, 2004)

�� ≤ � ≤ ��: ��(�) = ��. 2.5� (Fardis, 2004)

�� ≤ � ≤ ��: ��(�) = ��. 2.5� ��

�� (Fardis, 2004)

�� ≤ � ≤ 4��: ��(�) = ��. 2.5� ��

�� (Fardis, 2004)

Figure 28: Horizontal elastic response spectra

The peak ground acceleration was deemed 10.30m/s². Therefore base shear was calculated as: �� ℎ�� = 10.30�/�� × 20712.0 = 101.6�� As the structure consisted of one storey, the base shear was distributed to the top of the column at 6.7m. Therefore, the base shear was equal to the lateral seismic force.


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The lateral seismic force was input to LinPro as a load case. In addition, a seismic load combination was created including the seismic force and unfactored vertical loading. Figure 29 highlights the seismic load combination in LinPro. As the seismic force was deemed most onerous no other lateral force was considered i.e. wind load.

Figure 29: Seismic load combination used in static analysis

Figure 30 illustrates the location of lateral seismic force determined using the modal analysis and base shear.

Figure 30: Lateral seismic load input to LinPro

The bending moment diagram for the seismic load combination is shown in Figure 31. It was clear that the load combination had a severe reaction to the right hand rafter and column. This was anticipated due to the magnitude of lateral force imposed by a seismic event.

Figure 31: Bending moment diagram from seismic load combination


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The maximum bending moment produced by the seismic load combination included:

Steel column: 690.59kNm Steel rafter: 690.59kNm Apex haunch: 193.27kNm

Figure 32: Shear force diagram from seismic load combination

The maximum shear force produced by the seismic load combination included:


Figure 33: Axial force diagram from seismic load combination

The maximum axial force produced by the seismic load combination included:



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Conclusion

The seismic load combination input to LinPro produced higher forces in critical members. A steel performance analysis was again undertaken using the forces from the seismic action. The results have been tabulated below providing an assessment for if a critical member pass or fails. Table 7: Steel member performance subject to flexure

Minor Axis Buckling Major Axis Buckling

Maximum Moment

(kNm)

Allowable Moment

(kNm)

Pass/Fail Maximum Moment

(kNm)

Allowable Moment

(kNm)

Pass/Fail

Column 690.59 562.30 Fail 690.59 500 Fail

Rafter 690.59 762.70 Pass 690.59 762.70 Pass

Table 8: Steel member performance subject to axial force


Maximum Axial

Force (kN)

Allowable Axial

Force (kN)

Pass/Fail Maximum Axial Force

(kN)

Allowable Axial Force

(kN)

Pass/Fail

Column 113.03 1240.30 Pass 113.03 3455.30 Pass

Rafter 112.45 3822.5 Pass 112.45 3202.14 Pass

Table 9: Steel member performance subject to shear force


Maximum Shear

Force (kN)

Allowable Shear Force

(kN)

Pass/Fail Maximum Shear

Force (kN)

Allowable Shear

Force (kN)

Pass/Fail

Column 103.07 1062.9 Pass 103.07 1062.9 Pass

Rafter 130.70 1058.90 Pass 130.70 1058.90 Pass

The steel element assessment was performed and the results indicate that column 610x229x101UB (S275) failed in flexure. The maximum allowable moment for the section was deemed 500kNm in major axis buckling. It was observed that the section failed by 190.59kNm. However, the specified rafter and column passed in both axial force and shear force. It was observed that the maximum shear force in the rafter produced by the seismic load combination was less than load combination 1, from the initial static analysis. This was anticipated as the initial load combination 6.10(i) imposed a greater vertical force onto the structure.

In order to satisfy the seismic loading a greater column size will need to be selected. Furthermore, as the column was design in both minor axis buckling and major axis buckling, the allowable moment must satisfy both analyses. The steel section 610x229x140UB (S275) was deemed suitable to resist that flexure caused by a seismic event as the allowable moment was calculated as 808.4kNm, after including lateral torsional buckling.


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The portal frame will be stabilised by diagonal cross bracing founded in two bays, located at opposite ends of the structure. Furthermore, bracing will also be provided along the roof of the structure to provide resistance against wind suction. The bracing will be cross bracing therefore the wind force will be resisted by a tension member, which will be used to transfer the load to the column and into the foundation, as shown in hand sketches.

Construction Sequence

Terminal Building

Figure 34: Construction sequence: Stage 1

Stage 1

The principal contractor is given possession of the site after the client

has accepted the tender offer.

A full site investigation is completed by a sub-contractor which will

include a number of borehole logs and trial pits, in addition to a

contaminated land assessment. The contaminated land report will

assess if the site is contaminated which may result in ground

treatment prior to commencement of construction works.

A site boundary is established and steel mesh fence panels are

installed by a sub-contractor.

The site is scanned for services using a CAT scanner.

The principal contractor will apply to the local traffic authority to gain

permission for vehicles and plant entering and exiting the site via

Frederick Road.


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Stage 2 Site welfare facilities are delivered to site, installed on site, and

connected to services e.g. water, electricity.

Heavy plant is delivered to site.

Loose top soil is stripped where required on site. The loose material is

collected into a heap and is transported from site to a soil recycling

centre.

All spoil is removed from site and the site is levelled.

A surveying team sets out the location of the terminal building.

Underground services to site are calculated by a sub-contractor and

a drawing is issued to the principal contractor. The underground

services include a number of manholes and pipeline.

A temporary works sub-contractor will install sheet piled cofferdam to

allow installation of concrete manholes. Sheet piled trench

excavation and trench box are utilised to install pipeline on site.

Principal contractor imposes a site traffic management method

statement to ensure all site staff and pedestrians are safe during

vehicle movement.


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Stage 3

Excavation for the terminal building pad foundations and strip

footings are carried about in accordance to the foundation

specification and RC drawings.

A concrete mixer truck transports concrete to site.

A site engineer collects a sample of the concrete batch and a cube

test is performed at a chosen laboratory.

A steel fixing gang assembles the pad foundation reinforcement

cage in accordance to the RC detail drawing.

Terminal building pad foundations are constructed and left to cure.

A poker vibrator will be used to relieve the concrete of any air

pockets.

A sheet piled cofferdam is installed by a sub-contractor to enable

construction of the RC basement. The sheet piled cofferdam is

installed in accordance to the specification drawing and installation

sequence.

Steel UB and UC sections are transported to site via a lorry and

stored. The quality of steel is inspected by the site engineer.

Figure 37: Unloading of structural steel


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Figure 38: Temporary works cofferdam supporting basement excavation

Figure 39: Construction of basement floor slab in cofferdam


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Stage 4

Concrete shear walls are constructed prior to the erection of steel

sections. Timber formwork will be delivered to site and cut to

specification. Steel reinforcement cages will be constructed and

lifted into position within the formwork. The concrete will then be

poured and the shear walls will be left to cure. The concrete will be

vibrated using a poker to relieve any existing air pockets.

The shear walls will be temporarily propped to ensure stability during

the construction works. 2 No. 45° raking struts will be provided at

each face of the shear wall to ensure the walls do not overturn.

Concrete lift core will be constructed using the jump form method

where concrete is poured in stages. The concrete will be left to cure

before the formwork is removed. Once the formwork is removed the

working platform and formwork is raised to a higher level and the

process is repeated. The lift core will be constructed in accordance

to the specification drawings.


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Stage 5

A mobile crane is used to perform the erection of steel sections.

Scissor lifts are used by site staff to connect steel columns to steel

beams.

Steel UC sections are lifted by the crane and positioned on top of a

pad foundation where it is then bolted into position.

The steel frames will be connected to the lift core and shear walls.

Once connected to the steel work the temporary raking struts will be

disconnected from the shear walls.

The erection of the airport hangar will be constructed simultaneously

to the terminal building.

Concrete floor slab will be poured in accordance to the RC

specification drawings.

Figure 42: Steelwork erection


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Figure 43 Construction sequence: Stage 6

Stage 6

The installation of the roof trusses will commence following the

erection of all steel columns and beams. The roof trusses will be lifted

by the mobile crane and bolted into position in accordance to the

specification drawings.

Steel composite decking will be placed in between the first floor

beams and concrete will be poured to construct the upper floor

slabs.

Glass panels will be transported to site and stored securely to ensure

they are kept dry. The glass panels will be inspected by a site

engineer for quality prior to lifting.

The installation of building services are started by the sub-contractor.

Cladding panels are installed for both terminal building and airport

hangar.

Excavation for the car park and road is completed following the

pouring of the pavement sub-grade. The sub-grade will then be

compacted by a steam roller.


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Stage 7

Internal services are completed by sub-contractor including HVAC

and fire exits.

Specific facilities are installed including: restrooms, restaurant and

airport lounges.

Hot rolled asphalt is poured and compacted to provide surface

finishes to car park and roads. The thickness of asphalt will

constructed in accordance to the design specification. Car parking

bays are marked and road signage is poured for the one-way traffic

system.

Site welfare facilities, temporary fencing, and security gate are

removed from site.

A permanent airport security fence is installed around the proximity

of site and site is landscaped to the client’s requirement.

The airport is completed to the client’s specification.

The principal contractor passes possession of the site over to the

client after final inspection has been completed.


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Airport Hangar

Figure 45: Surveying of site and setting out

Stage 1

Firstly, it will be necessary to provide a site boundary fence around

the perimeter of the proposed structure to ensure no trespassers

enter the site. The site boundary wall will consist of temporary Herras

mesh fencing panels which will be founded on standard ‘plastic

feet’. The site fencing will be installed by site laborers as the mesh

panels are lightweight and are easily moved.

A site investigation report will have already been completed

therefore no ground testing will be required.

A maximum of two surveyors will be utilised to set out the locations of

each pad foundation, which will be founded below each steel

column. The surveying team will use a total station to mark out the

structure. As this is a highly important stage of construction sequence

a competent surveying team will be required.

The full design of the portal frame has been included in the structures

section of the submission. In addition, AutoCAD drawings have been

created to suit the structural design specification and will be utilised

on site when constructing the structure.


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Figure 46: Excavation for pad foundation

Stage 2

After setting out the position of pad foundations an excavator will be

required to remove earth. The depth of pad foundation will be

determined by the geotechnical engineering section of the

document.

A backhoe will be used to excavate at the location of pad

foundations.

The spoil will be collected at the middle of the site and will be

removed from site by truck.

The truck will transport the unwanted spoil to other areas of the site.


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Figure 47: Construction of concrete pad foundation

Stage 3

Steel reinforcement bars are transported to site by lorry and

assembled on site by the steel fixing team, in accordance with the

RC specification and drawings.

The reinforcement cage will be lifted by a minimum 2 laborers and

placed into the excavation. However, the weight of the

reinforcement cage should be assessed prior to lifting and if

deemed too heavy a crane will be required to place the

reinforcement.

Concrete spacers will be attached to the bottom reinforcement

bars to ensure that a minimum concrete cover is provided between

earth and reinforcement.

Concrete mixer will transport the specified concrete batch to site. A

concrete chute extension will be attached to the mixer truck to

allow accurate pouring of concrete into the excavation. A poker

vibrator will be used after the concrete has been poured to remove

any air bubbles within the concrete.

The concrete will be left to cure.

Steel mesh reinforcement will be placed and timber formwork will be

installed prior to pouring the concrete floor slab. The floor slab will be

constructed and left to cure prior to erection of steel columns and

rafters.


126

Figure 48: Erection of steel portal frame

Stage 4

Steel sections will be transported to site via wagons. The steel will be

placed within the boundary fencing and the steel quality will be

checked by a site engineer.

The steel sections will be drilled to allow for bolt connection between

steel elements. A baseplate will be prefabricated to UC sections

before arriving at site.

A mobile crane will be used to erect the steel universal columns into

position. The position of the UC section will be set out by the

surveying team.

A baseplate will be used to connect the UC section to pad

foundation. The baseplate will be connected to the pad foundation

using Hilti resin anchor bolts.

After two UC sections have been erected and fixed into position, the

rafters will be erected by the mobile crane and bolted into the UC

sections. A scissor lift will be used to allow laborers to connect the

steel elements together.

A risk assessment will be used prior to laborers using a scissor lift to

ensure all hazards are mitigated.


127

Figure 49: Completion of steel erection

Stage 5

All steel sections will be erected using the mobile crane and installed

in accordance with the structural drawings.

All steel sections should be checked by a site engineer for quality

assurance prior to lifting.


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Figure 50: Installation of purlins and cross bracing

Stage 6

Vertical steel bracing will be installed between each internal column

to provide stability against wind pressure.

Horizontal steel bracing will be installed on the roof between each

internal rafter to provide stability against roof uplift caused by wind

suction.

Steel Z shaped purlins will be installed across the side faces of the

structure. The Z purlins will be connected to each column and rafter

using an end cleat. The end cleat will be shaped at a right angle

and four bolts will be used to connect the purlin to the steel sections.

A mobile crane will be used to lift the purlins into position and scissor

lifts will be used to allow laborers to connect the purlins to the UC &

UB sections.


129

Figure 51: Installation of cladding and internal services

Stage 7

Aluminium cladding will be transported to site using a number of

heavy goods vehicles. The cladding will be pre-manufactured off-site

to the correct specification therefore the cladding can be installed

on site after quality inspection is completed.

The cladding panels will be lifted using a mobile crane and scissor lifts

will be used by the labour gang to bolt the cladding to the Z purlins.

Internal services (HVAC) are installed by a number of sub-

contractors.

Final inspection is performed by site engineer and principal

contractor.

Client is informed of structure completion.


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Geotechnical Engineering

Introduction

In regards to the Structure module it was requirement to complete a detailed design for 1 structure within the airport site. In semester 1 the design group considered three design concepts for the aircraft hangar. Subsequently, it was a requirement for the design group to choose one of the design concepts in semester 2, to complete a full detailed analysis. Therefore, it was decided that the aircraft hangar was to be designed as a steel portal frame. The structural design of the portal frame was completed in the Structures chapter within this document. The geotechnical engineering requirement for semester 1 was to investigate three foundation concepts which may be utilised for a structure on the airport site. Semester 1 investigated shallow foundation including strip, pad, and raft foundation. The information obtained in the feasibility study was used to determine the most appropriate foundation scheme in this chapter.

The portal frame consisted of a number of steel columns and rafters spaced at 6.0m intervals. The building envelope was 36m x 30m. The column-foundation connection was pinned. This resulted in no bending moment in the footing therefore the design considered a maximum concentric axial force from the steel column.

Foundation Design

Foundations should be planned using the Eurocode BS EN 1997-1: 2004 and particularly for the outline of concrete structures BS EN 1992-1-1: 2004. Also, reinforced concrete should be designed using BS 8500-1. Further assistance can be found using BRE Special Digest SD1 where concrete foundations are placed within destructive ground states (Government, 2007).

The purpose of a foundation is to absorb the loading imposed by a superstructure. It exchanges the moments and forces from the structure to the underlying soil such that the stresses in soil are inside reasonable points of confinement and it gives constancy against overturning and sliding to the structure. The duty of a geotechnical engineer is to guarantee that the underlying soil and the foundation are safe against failure and don’t encounter unnecessary settlement(Terzaghi, 1943). The bearing capacity calculation of foundations happens to be one of the most fascinating issues faced by the researchers and geotechnical specialists. Throughout the years, the bearing capacity of a footing has been broadly explored both experimentally and hypothetically. While planning foundations, specialists and engineers must fulfil two perquisites, for example, complete collapse of foundation must be evaded with satisfactory margin of safety and relative settlement should be within restricts that can be endured by


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structure. The ultimate bearing capacity of a foundation is characterised as the maximum load that the ground can maintain which is the ‘general shear failure’; where the load settlement bend does not show a peak load. The bearing capacity is appropriate as the load at which the bend passes into a precarious and genuinely straight tangent which is the ‘local shear failure’(Terzaghi, 1943).

The foundation type which will be utilised beneath the airport hangar is a pad foundation. Pad foundations are used to upkeep individual or even different columns, disseminating the load to ground beneath. It is usually rectangular or square in arrangement, with the arrangement area being established by the permissible bearing capacity of the soil. The form in the plan will be directed by the arrangement of the columns and the load to be occurred into the soil. The thickness of the slab must be enough to guarantee dispersal of the load. Sometimes, the pad may be inclining from the top therefore the center is much thicker than the edges of the pad. This can be an economic arrangement however there may be development issues included with casting the slope. In basic cases the pad may be constructed from mass concrete. However, steel reinforcement will be needed whether it is welded steel fabric or reinforcing bars in both directions, within the concrete. For outline purposes, the pad is dealt with as though it were an inverted cantilever conveying the soil weight and supported by the column.

Figure 52: Modes of bearing capacity of failure of soil. (a) General shear failure; (b) local shear failure (Terzaghi, 1943)


132

When calculating the bearing capacity for the pad foundation, Skempton’s bearing pressure was used, as the footing was constructed in cohesive soil. Skempton proposed a bearing capacity hypothesis for saturated clay (φ = 0). It provided NC, the bearing capacity factor on the

basis of principle and research tests. It was observed that the value of NC expanded with the increment in DF/B proportion. It was observed that bearing capacity factor Nc varied with foundation depth.

Another method that was used was Terzaghi’s bearing capacity equation for shallow foundations. Terzaghi’s theory was utilised in order to compare the values with Skempton’s method and to verify that the Skempton’s method is suitable. Terzaghi’s equation is derived from these following assumptions, which is; the soil is homogenous and isotropic, the footing has a rough base and is continuous. Also the soil over the base of the foundation is replaced by a constant surcharge (Terzaghi, 1943).

Terzaghi’s method is used for any type of soil and (N) does not rely on the depth of the foundation(Apparao & Rao, 2005). Shallow foundation is recognized as a footing laid on stratum with enough bearing capacity, placed less than 3m below the ground level. Few examples include strip, raft or pad foundation.

The type of footing used for the airport hangar is pad foundation. The foundation size for the pad was 1.5m x 1.5m, using Skempton’s method. The size of the foundation is important due to the amount of concrete required and the excavation depth. The aircraft hangar will be designed as a steel portal frame where internal columns will be spaced at 6.0 m intervals. Therefore, a pad footing under every column will make the structure efficient compared to strip footing as this may result in waste of unnecessary material. Furthermore, if the pad foundation was too large the pads may clash and it would be more suitable to consider a strip footing. As the airport needed to tackle sustainability it was decided that a pad foundation would be fitting as only the required reinforced concrete would be used.

The design considered a Eurocode 7 check to determine the suitability of the foundation using two combinations. Eurocode7 UK national annex Design Approach 1 needed two groups of different calculations to be achieved using a number of partial factors. Combination 1 is related to the structural actions of foundation and combination 2 is related to the ground properties (Apparao & Rao, 2005).


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Table 10: Eurocode 7 partial factors

Permanent load (Gk)

Leading Variable load (Qk)

Accompanying Variable load (Qk)

DA1

Unfavourable

Favourable

Unfavourable

Favourable

Unfavourable

Favourable

C1 1.35 1.00 1.50 0 1.50 0

C2 1.00 1.00 1.30 0 1.30 0

Table 11: Eurocode 7 partial factors for soil parameters

Angle of Shearing

resistance (γφ)

Effective Cohesion

(γC)

Undrained Shear

Strength (γCU)

Unconfined Strength

(γqu)

Bulk Density

(γγ)

Combination 1 1.0 1.0 1.0 1.0 1.0

Combination 2 1.25 1.25 1.4 1.4 1.0

After completing the design check using Eurocode 7, design approach 1: combination 1 and combination 2, the 1.5m x 1.5m pad foundation was deemed acceptable.

A settlement check was undertaken to ensure the 1.5m x 1.5m foundation was suitable in regards to displacement. The consolidation of a material is usually related to settlement calculation of foundation under load on clay. As cohesive material contained pore water pressure, a consolidation analysis was determined to observe the increase in settlement under effective stress conditions. There are three elements linked to the settlement of a foundation, which includes the elastic settlement, primary settlement and secondary consolidation settlement.

After completing the settlement analysis, the maximum anticipated settlement when the clay had consolidated was 46.8 mm. This was deemed acceptable (<50mm) therefore the foundation passed all checks. The degree of consolidation for the clay was determined for 24 month time period. Therefore, hand calculations determined that the clay will be 95% consolidated after two years. The hand calculations to determine settlement was compared against a 2D geotechnical finite element analysis in Plaxis in addition to a 2D linear elastic analysis, completed in LinPro.


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Linear Elastic Analysis

The vertical load, calculated when determining the dimensions of the pad footing, was used to determine the structural forces in the foundation. The maximum vertical load acting onto the pad foundation was 194kN. It was necessary to determine the forces in the foundation in order to complete a reinforced concrete design to EC2. The maximum bending moment was used to determine the required shear reinforcement. A 2D linear elastic model was produced using the software LinPro. The beam on elastic foundation analogy was considered utilising Winkler springs to model the soil stiffness. The modulus of subgrade reaction (ks) was used to represent the underlying soil beneath the footing. (Bowles, 1997) provided a number of value ranges for the modulus of subgrade reaction for cohesive and granular soil. As the foundation would be constructed on top of cohesive material, Table 8 was used to determine a suitable value for the modulus of subgrade reaction (ks). Table 12: Modulus of subgrade reaction for cohesive soil (Bowles, 1997)

Soil Classification Modulus of subgrade reaction (ks) (kN/m³)

Clayey soil:

200 <

qa ≤ 200 kPa 12,000-24,000

qa ≤ 800 kPa 24,000-48,000

qa > 800 kPa >48,000

Therefore, a 2D linear elastic model was created in LinPro using a beam supported by a number of springs. The beam was 1.50m in length to accurately represent the width of foundation. In order to obtain accurate results a spring was placed at every 0.10m interval below the footing. Furthermore, horizontal springs where input to the ends of the beam. The maximum vertical load was input at the centre of the foundation as the pad footing was designed concentric. As the column-base connection was pinned this resulted in no moment acting onto the footing. The forces calculated using the beam on elastic foundation was recorded and compared against a geotechnical finite element analysis in Plaxis.

Figure 53: Beam-spring model created in LinPro


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The value for the modulus of subgrade reaction (ks) was input to represent both total stress (short term conditions) and effective stress (long term conditions). (Haynes, 2014) suggests that the modulus of subgrade reaction for effective stress conditions should be a value of one third of that considered for total stress. This is due to the dissipation of pore water pressures in the clay which in turn will reduce the stiffness of the soil. A value of 20,000kN/m³ was assumed from Table 9 to represent the soft clay that contained an undrained shear strength of 32kN/m².

Figure 54 showed the shear force in the foundation, analysed in LinPro. It is clear that the maximum shear force in the footing was located directly beneath the applied axial force. The diagram indicated that the magnitude of shear force in the footing gradually reduced as it moved away from the point load.

Figure 54: Shear force diagram for beam-spring model

Figure 55 showed the bending moment envelope for the footing. The maximum anticipated bending moment was recorded as 35.7kNm, located directly below the point load. The maximum moment will be used to complete the reinforced concrete design to Eurocode 2. The bending moment envelope was produced to represent total stress conditions, utilising a modulus of subgrade reaction (ks) of 20,000kN/m³.

Figure 55: Bending moment diagram for beam-spring model

Figure 56 represents the bending moment envelope for the footing on clay during effective stress conditions. It was observed that the bending moment in the footing increased when the clay consolidated. This was anticipated as the strength of the clay would reduce when pore water pressure dissipated from the soil, causing higher stress beneath the footing.


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Figure 56: Bending moment diagram for effective stress conditions

The use of the beam-spring concept contained a number of benefits and limitations. The main benefit of this analysis method is that the structural forces in the foundation may be determined relatively quick, in comparison to a geotechnical finite element analysis. The beam on elastic foundation theory assumed that the soil beneath the foundation behaved in an isotropic linear elastic manner. However, in reality the underlying soil is not isotropic due to a number of stratigraphy recorded from the boreholes. Also, in reality soil behaviour is non-linear elasto-plastic. For this reason the foundation settlement was not recorded using the beam-spring method as it was deemed to calculate inaccurate values.

The beam on elastic foundation theory did not determine the global stability of the soil. In reality, cohesive soil adjacent to the footing may heave. Unlike a geotechnical finite element analysis, the beam-spring theory was not able to determine this soil behaviour. The beam-spring model produced a basic representation of soil-structure interaction, however it was only used to determine the structural behaviour of the footing. A geotechnical finite element analysis was more complex therefore it was deemed to produce a better representation of soil-structure interaction.

Geotechnical Finite Element Analysis

In order to validate the settlement hand calculations for the pad foundation, a geotechnical finite element analysis was completed using Plaxis (ver. AE). The analysis considered a 2D representation of the footing as the group was unable to access a 3D geotechnical finite element analysis software. Furthermore, Plaxis was used to determine the structural forces in the footing and a consolidation analysis was undertaken for a 24 month period to determine the soil behaviour. The settlement was determined for both short term and long term conditions. The structural forces where compared against the 2D linear elastic analysis and conclusions where made based on reliability of each analysis method.

The main purpose of conducting a geotechnical finite element analysis was to assess the soil-structure interaction, between footing and soil. The Winkler spring concept was utilised in LinPro as a beam supported by a number of springs. This analysis method was useful in obtaining the


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structural behaviour of the foundation. In order to determine the soil behaviour a finite element analysis was required.

The Plaxis model was produced using the design borehole considered in the feasibility report. The design borehole was determined using the two boreholes provided in semester 1. Figure 57 shows the types of soil used to make the ground profile. The design borehole indicated alluvium/ soft clay was present at the depth where the foundation was to be constructed. The borehole indicated Made Ground to a depth of 1.30m BGL however, this was disregarded in Plaxis as it was assumed an initial 500mm would be stripped on site, followed by a 1.50m deep excavation for the footing.

Figure 57: Soil types input to Plaxis

The soil was modelled in Plaxis using the Mohr-Coulomb model. This was deemed the most appropriate soil method for the soil parameters we had received in the site investigation report. The Mohr-Coulomb soil model required the Young’s modulus for soil (E), Poisson’s ratio (�), soil density (γ), and undrained shear strength (Su). 瘣The Young’s modulus (E) was determined using the following relationship: The Young’s modulus (E) was determined using the following relationship: � = �. �� Where (K) was considered 750 for a normally consolidated and lightly over consolidated clay (Bowles, 1997, p. 127). Therefore the value for Young’s modulus (E) for the cohesive soil was deemed: � = 750 × 32 = 24,000��/�² A value of 20MN/m² was chosen as a conservative value for (E). Figure 58 shows how the soil parameters where input to Plaxis.


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Figure 58: Soil parameters input to Plaxis

After the ground profile had been created the foundation was inputted. Plaxis considered structural elements as flexible plates therefore a plate was input 1.50m in length, at the centre of the mesh. This allowed for even stress distribution in the nodes. The foundation parameters where input in the plate materials tab where the Young’s modulus (E), second moment of area (I), and area (A) where determined by hand. The foundation parameters included:

- Young’s modulus � = 22 ��

��

�.�� (Leach, 2012)

= 22 ��

��

�.��= 32.8��/��² = 32.8�10��/�²

- Second moment of area � =��

��

=��

��=

�.��.�.��

��= 0.0156��

- Area = 1.50 � 0.50 = 0.75�²

A point load was input to Plaxis to represent the maximum vertical load acting onto the pad foundation. The point load was applied at the centre of the foundation to ensure concentric loading. The mesh was then generated within Plaxis and the construction stages where determined. As the model was concerned with settlement the generated mesh for the clay was refined to obtain more accurate results.

Figure 59 shows the Plaxis model at the initial stage where no foundation has been constructed.


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Figure 59: Generated soil mesh in Plaxis

Figure 60 shows the Plaxis model at the second stage after the pad foundation was constructed and immediate settlement has taken place.

Figure 60: Soil deformation caused for pad foundation

Figure 61 shows the Plaxis model at the third stage where the 194kN point load is applied to represent the imposed loading from a steel column, supporting the portal frame.

Figure 61: Soil deformation caused by erection of portal frame


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Figure 62 shows the Plaxis model at the fourth stage. This stage included a consolidation analysis for a time period of 24 months. It was determined by hand that the clay would be 95% consolidated at this time. The deformed shape of the soil clearly indicates that after pore water pressures had dissipated from the cohesive material, this will cause the soil to heave. The soil heave height was approximately 100mm around the foundation.

Figure 62: Long term soil deformation

Figure 63 shows the maximum soil deformation line recorded at the consolidation stage. The image suggests that the maximum soil deformation would occur below the point load. This was anticipated as the soil stress beneath the footing would be greatest directly below the point load.

Figure 63: Location of maximum soil displacement in Plaxis

Figure 64 shows the magnitude of soil deformation after construction of the pad foundation. It was observed that the greatest soil displacement occurred directly below the footing and soil deformation gradually reduced the further away from the foundation.


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Figure 64: Soil displacement caused by pad foundation

Figure 65 shows the magnitude of soil deformation after the erection of the steel portal frame. It is clear that soil deformation it more intense below the footing. Unlike Figure 64 the deformation bulbs have become more circular after the point load was applied. This occurred because the force acting on the foundation was greatest at the centre of the footing.

Figure 65: Soil displacement caused by portal frame

Figure 66 shows the magnitude of soil deformation after the consolidation analysis was completed. It was observed that the deformation in the lower strata reduced over time.


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Figure 66: Soil displacement during long term conditions

Figure 67 illustrates the recorded soil deformation below the pad foundation. It was recorded that the maximum settlement occurred after the clay had consolidation with a value of 30mm.

Figure 67: Maximum soil settlement beneath pad foundation

Figure 68 shows the arrows of soil deformation after the clay had consolidated. The image clearly indicates that the soil will heave around the edges of the foundation.

Figure 68: Long term soil displacement showing heave


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As the pad foundation was analysed in Plaxis as a flexible plate, it allowed the design team to determine the structure forces in the footing. The structural forces in the footing where determined using the imposed loading and stress in the underlying soil. The structural forces in the foundation where observed to be greatest after the clay had consolidated.

Figure 69 illustrates the bending envelope for the foundation at final stage. The shape of the bending moment diagram is very similar to Figure 56 for the linear elastic model produced in LinPro. The bending moment envelope in Plaxis suggests that maximum flexure in the foundation was located directly below the point load. The results of the bending moment where compared against hand calculations and the LinPro model, resulting in the most onerous force used to produce the reinforced concrete design.

Figure 69: Bending moment envelope for pad foundation in Plaxis

Figure 70 shows the shear force envelope for the foundation at critical stage. It was observed that the shear force diagram was very similar to Figure 54 therefore the results have been deemed reliable. The maximum and minimum shear force was located directly below the point load.

Figure 70: Shear force envelope for pad foundation in Plaxis


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Conclusion

The results, shown in Table 10, indicate that the calculated settlement in Plaxis was less than the hand calculations. This was anticipated as the hand calculations considered rigid soil mechanics thus assuming the density between underlying soil and foundation was the same. However, the bending moment and shear force results calculated in LinPro and Plaxis where observed to be similar. The geotechnical finite element analysis indicate that the settlement beneath the foundation is acceptable as it is less than 50mm.

Table 13: Results table for the three methods of analysis

Analysis Method Bending Moment (kNm)

Shear Force (kN)

Settlement (mm)

Hand Calculations 36.40 97.0 46.82

LinPro 37.70 97.0 -

Plaxis 38.60 97.0 30.90

There are a number of benefits to performing a geotechnical finite element analysis in comparison to a static analysis. (Potts & Zdravkovic, 1999) suggests that a full soil-structure assessment may be undertaken to observe the behaviour of both soil and foundation. This is beneficial as a 2D linear elastic analysis, completed in LinPro, only assessed the structural behaviour of the footing. (Potts & Zdravkovic, 1999) states that a finite element analysis may evaluate the global stability of the soil. This was determined in Plaxis through a consolidation analysis to assess soil heave.

Alternatively, there are a number of limitations to using a geotechnical finite element analysis. Firstly, it is assumed that soil behaviour is linear elastic where in reality soil behaviour is non-linear elasto-plastic. Also, in order to obtain reliable results a thorough site investigation report including borehole will be required. Therefore, in reality a site investigation report may cost the client additional expenses and more time to construct the substructure. Finally, in comparison to a beam-spring model, the time required to complete an analysis in Plaxis was significantly higher.

The final results indicate that the 1.50m x1.50m pad foundation will be suitable to support the aircraft hangar. A reinforced concrete design for the pad foundation will be completed within the Structures chapter of this report.


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Base Heave

The terminal building would contain a basement located 4.0m below ground level. The basement was constructed with the aid of a sheet piled cofferdam, in order to retain the soil so the basement walls could be constructed. The temporary works sheet piled cofferdam would be founded in clay therefore it was important that base heave did not occur, as this would disrupt the construction of the basement floor slab. The following pages include calculations to determine the factor of safety against base heave failure.


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Transportation

Introduction The airport will comprise of a number of structures which will need to be designed to satisfy the Transportation module requirement. In accordance to the clients brief it was an obligation to design an airport that would accommodate small aircraft carrying a maximum of three passengers. In addition, customers would be able to visit the airport using suitable commuting options. The airport will be constructed on the David Lewis recreational ground adjacent to Frederick road. The airport was designed to contain a road which allowed customers to enter a car park and/or enter a drop-off zone outside of the terminal building. The new road will be designed to utilise a one-way system in order to reduce traffic.

Figure 71: Airport concept highlights roads and carpark

The choice of pavement type for all areas which require vehicular movement within the airport facility will be flexible pavements. There are many advantages that flexible pavements have over rigid pavements, these are as follows: the construction of pavements with asphalt surface finishing i.e. flexible pavements is less demanding such that repairs and renovations are simpler and cheaper than rigid pavements (Kazda & Caves, 2000). The reconstruction of flexible pavements can be carried out even without interrupting operations if the works are performed by night (Kazda & Caves, 2000). Flexible pavements also withstand winter maintenance better than rigid pavements when chemical de-icing materials are used (Kazda & Caves, 2000). Not having to use joints on the surface like rigid pavements do is an added bonus. Other advantages of using asphalt material are that the surface skid properties don’t deteriorate very fast, making it more sustainable in this regard. Due to the flexible property of asphalt surface noise can be reduced somewhat compared to rigid pavements. This is important as airport facilities tend to be noisy


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environments thus any sort of noise reduction will be an added bonus for surrounding environments.

Traffic Control Devices

Signage

Traffic signs which lead people to the airport as well as appropriate traffic signs to guide pilots within the airport will be required. Traffic guide signs such as large signboards indicating the existence and location of the airport will be implemented on the A6/Broad Street as well as the A56/Bury New road and used by guiding people to the entrance of the airport located on Frederick Road, see below.

Figure 72: Main link roads to airport site


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Figure 73: Entrance and exit airport site roads

Regulatory traffic signs in the form of no entry will be used at the exit of the airport site in order to prevent drivers from entering through that particular road opening as the entrance will be located at a different place to the exit (see Figure 73 for more details). The general speed limit of airside roads is 20mph (Cambridge Airport Procedure, 2013), thus starting at the entrance of the airport 20mph speed limit signs will be implemented. These signs will be repeated at the entrance of each airside road i.e. roads within the airport facility. One way road signs will be implemented on the three airside roads surrounding the car park; this will help with controlling the traffic in order to make drivers abide by the no entering through the exit and no exiting through the entry gates rule etc.

The following key mandatory guide signs in order to guide pilot(s) within the airport facility will be implemented. The signs that will be used are:

Traffic Floor Markings

Key floor markings will be used to guide pilot(s) within the airport facility. Floor markings in the form of zebra crossing will be used on the airside road parallel to the longer dimension of the car park in order to aid pedestrians in reaching the terminal building more safely. The floor markings that will be used in order to help with the aircraft ground operations are as follows:

Floor marking denoting entrance to runway from taxiway e.g.

Floor markings separating movement area for aircraft to non-

movement area e.g.

Floor makings which define the edge of a useable full strength

taxiway e.g.


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Alphabetically lettered signs identifying a particular taxiway e.g.

Numbered signs identifying a particular runway e.g.

Sign identifying entrance to runway from a particular taxiway e.g.

No entry signs at prohibited areas for aircraft e.g.

All images have been referenced from the Federal Aviation Administration http://www.faa.gov/airports/runway_safety/news/publications/media/QuickReferenceGuideProof8.pdf [accessed 31 March 2015].

Taxiways in an airport serve the purpose of acting as a transition zone for aircrafts between being statically parked to getting ready for take-off on a runway (Kazda & Caves, 2000). Taxiways are identified by a continuous yellow centreline stripe and may include edge markings to define the edge of the taxiway as can be seen in Figure 74, below (Flight Learnings, n.d.). This is usually done when the taxiway edge does not correspond with the pavement hence used to differentiate between the two. If an edge marking is two solid continuous lines parallel to each other, the paved shoulder is not intended to be used by an aircraft. If the edge marking has two dashed lines parallel to each other the aircraft may use the other side of the paved shoulder (Flight Learnings, n.d.). The two solid lines along with two dashed lines denoting the entrance to a runway can be used even at intersecting runways which will not be the case for this design as there is only one runway (Flight Learnings, n.d.).


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Figure 74: Airport floor marking layout example (Flight learnings, n.d.)

Non-signage/marking visual aids

Figure 75: General features of a heliport (Federal Aviation Administration, 2012)


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Guiding non ground operations such as landing for both helicopters and aircraft to the appropriate destination(s) (heliports and runways) can be a little trickier than ground operations which can be achieved through appropriate signage applications as mentioned above. Therefore non-signage methods need to be implemented such as through lighting and a wind indicator.

A minimum of four flush lights is to be used per side of a rectangular final approach and take-off area (FATO) and touchdown lift-off surface (TLOF). A light is located at each corner with additional lights uniformly spaced between the corner lights with a maximum interval of 7.5 m between lights (Flight Light, 2015).

An FAA L807 Size 1 (about 22 ft. overall height with an 8 ft., international orange windsock) will be implemented. The L807 has a hinged pole and a rigid base. The L807 must be outside the safety zone and away from flight paths as seen in Figure 75 (Flight Light, 2015).

Guiding aircraft during night hours will be done using lighting systems also. Taxiway centre lines will be defined with unidirectional green lights spaced at 15 m intervals. Blue lights will be set at the same intervals in order to define the edges of the taxi route (Flight Light, 2015).

In order to guide aircraft pilots in landing and taking off during non-daylight hours it is often sufficient to apply edge lights on the runway edge, runway threshold (beginning), runway centreline and runway end (Kazda & Caves, 2000).

Airport Road Design The site road was designed using the maximum number of anticipated vehicles, including OGV1+PSV and OGV2. The client provided the peak traffic flow on Frederick road in both directions. The peak traffic flow was 450 vehicles/ hour. The site road design utilised the peak traffic flow on Frederick road to estimate the number of vehicles that would enter the airport site. The flexible pavement design did not consider the million standard axles (msa) for small vehicles such as cars, as the weight would not exceed 1.50 tonnes. Therefore, only vehicles greater than 1.50 tonnes where considered. The road pavement design was completed using hand calculations provided on pg. 169. The hand calculations show the process used to determine the depths of individual layers within the flexible pavement.

Figure 76 shows the graph used to determine the percentage of OGV2 vehicles for the road design. The AADF was calculated as 1,080


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vehicles/day, based on the maximum AADF for Frederick road. The graph indicated that the minimum percentage of OGV2 vehicles that must be considered when designing the road was 42%.

Figure 76: Minimum percentage of OGV2 vehicles

In order to determine the design traffic (msa) to complete the pavement design, the wear factor and growth factor for OGV1+PSV and OGV2 was determined. As the pavement design was for a new road the design code provided the relevant data. As the flexible pavement was designed for 40 years the wear factor considered the wear to the pavement caused by different types of vehicles.

Figure 77 indicated that for a new road OGV1+PSV should consider a wear factor equal to 1.0. Furthermore, OGV2 vehicles should consider a wear factor equal to 4.4.

Figure 77: Wear factors for the design vehicle types

The growth factor for the two vehicles types where determined using Figure 78. A growth factor was used when determining the design traffic to account for the growth in number of vehicles over a 40 year time period.


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Figure 78: Growth factors for design vehicle types

Figure 79 was used to determine the percentage of commercial vehicles in the heaviest traffic lane. Based on the 1080 AADF, 94% of commercial vehicles was determined.

Figure 79: Percentage of vehicles in heaviest traffic lane

The design traffic (msa) for the site road was determined using the formula:

� = (365 × � × � × � × � × �)/10� (msa)

The design traffic was calculated as 56 million standard axles for a 40 year time period. This value was used to determine the flexible surface thickness and base.

Figure 80 illustrates the graph used to determine the pavement thicknesses, governed by the millions standard axles for design traffic. Furthermore, the graph indicated two possible options for the pavement design. Therefore,


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one distinct scheme was chosen. It was determined that a hydraulically bound mixture for the base would provide the pavement with a better load distribution capability, therefore this option was chosen.

Figure 80: Design flexible surface thicknesses for site road

The thickness of capping layer and sub-base was determined using Figure 81. In accordance to the design brief a number of boreholes where provided, indicating that the pavement would be founded on clay containing an undrained shear strength of 32kN/m². This indicated soft, sandy clay present. Subsequently, a CBR for the cohesive material was estimated as 5%. The CBR was input to Figure 81 and the sub-base and capping thicknesses where determined.

Figure 81: Capping layer and sub-base thicknesses


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Airport Car Park Design

The airport car park was designed as a flexible pavement due to the low anticipated loading from vehicles. The car park was to be used by small vehicles such as cars and motorbikes. To complete the pavement design the process used to design the airport road was implemented. However, as the airport road was subject to axles loading from OGV2 vehicles, a different traffic assessment was required.

The design team used their engineering judgement to conclude that the car park would be subject to million standard axles no greater than 5.0, over the 40 year life expectancy. This was considered a suitable and conservative estimation for the design traffic. The design traffic was input to Figure 82 to determine the two possible schemes for the flexible pavement.

Figure 82: Capping layer and sub-base thicknesses

The first option was to construct a hydraulically bound mixture (base) with an asphalt surface. The second option was to construct a base and surface using heavy duty macadam and dense bitumen macadam. It was observed that the total depth of the pavement for both options was the same therefore, the flexible pavement was designed using option 1 as it coincided with the design for the airport road. The subbase and capping layer was determined using a CBR of 5%, therefore the same thicknesses where considered for the airport road design, shown in Figure 82.

Airport Runway Design The design of the airport runway was deemed more complicated in comparison to the site road and car park as there was no set design guide. The runway pavement design is governed by the weight of the largest


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aircraft and the annual number of departures. Therefore, in order to complete the runway pavement design an aircraft, deemed most onerous to the runway, needed to be chosen in addition to the annual departures.

The airport runway was to accommodate small aircraft, in accordance to the clients brief. It was envisaged that each aircraft using the runway could accommodate a maximum 3 persons per flight. Therefore, research on small aircraft was undertaken in the Feasibility report to determine the weight and maximum tyre pressure. The airport runway was designed using Beech 35 series aircraft. The maximum take-off weight of the aircraft was 1542kg (15kN). Furthermore, the maximum tyre pressure for this aircraft was 0.30MPa.

In order to design the sub-base and capping layer the CBR (%) was considered. (Ministry of Defence, 2011) suggests that if the runway is designed as a flexible pavement it should consider the CBR model, however a rigid pavement should consider the modulus of subgrade reaction (ks). The frequency of trafficking of the aircraft on the runway also needed to be determined to design the runway surfacing. (Ministry of Defence, 2011) suggests in order to determine the frequency of trafficking the aircraft classification number (ACN) needed to be calculated. Figure 83 was used to determine the ACN for the chosen aircraft.

Figure 83: ACN for design aircraft

The number of coverages for the model aircraft was determined using the formula:

�� = �� × �� × �� /��

��

�� = �� × �� × ��

�= 48,666

As the maximum number of coverages was greater than 10,000 but less than 100,000, a medium frequency of trafficking was decided, shown in Figure 84.

Figure 84: Number of coverages for design aircraft


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The collected information was then used to determine the flexible surface for the runway. (Ministry of Defence, 2011) suggests that a runway supporting aircraft with a tyre pressure less than 0.50MPa and medium frequency of trafficking should use hot rolled asphalt (surface) with macadam binder course, as shown in Figure 85. The runway surface would be constructed on top of a base course. The base course thickness was determined using Figure 82 and comprised of a hydraulically bound mixture (category A).

Figure 85: Runway surface type for design aircraft and trafficking frequency


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Airport Site Road

Table 14: Site road pavement thicknesses

Pavement Layer Thickness (mm)

Material

Surface 50 Hot rolled asphalt (HRA)

Binder 130 Heavy duty macadam (HDM)

Base Course 180 Hydraulically bound mixture (HBM) category C. Gravel course aggregate

CBGM B – C12/15 (T4)

Sub-base 150 Granular Type 1

Capping 250 Crush aggregate, recycled materials

Airport Car Park

Table 15: Car Park pavement thicknesses


Material



Base Course 160 Hydraulically bound mixture (HBM) category B. Gravel course aggregate

CBGM B – C12/15 (T4)



Airport Runway

Table 16: Airport runway pavement thicknesses


Material



Base Course 180 Hydraulically bound mixture (HBM) category A. Gravel course aggregate

CBGM B – C8/10 (T3)




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Maintenance of Flexible Pavements

There are three levels of maintenance for flexible pavements

1. Surface treatments 2. Minor maintenance 3. Major maintenance

Looking firstly at surface treatments, this is a treatment targeting the surface of a pavement which can be broken down into smaller sub treatments. The first being crack sealing, which as the name suggests, is repairing cracks on the surface of a pavement. Crack sealing will be used to prevent water from reaching the sub-grade of the pavements on site through cracks, this is important as it will stop the water from damaging the bearing course thus saving the need to perform major repair/maintenance in the future. Narrower cracks can be sealed by infilling, wider cracks (more than 20mm) require surface sealing using textured skid resistant materials (Transport, 1994).

Another sub surface treatment that will be used in maintaining the pavements in the airport is surface dressing which is one of the more common methods used for the maintenance of road surfaces. In its simplest form, a thin layer of bituminous binder is applied to the road surfaces and stone chippings are spread and rolled. This method will be used because a surface dressing slows down the deterioration of the road structure by sealing the surface and also increases the texture and skid resistance of the pavements, thus making it more safe and sustainable (Transport, 1994)

Minor maintenance methods such as patching will be used when defective material is detected on the surface course. This can be due to a number of reasons such as gradual deterioration of the bituminous surface material leading to pot holes, water penetration along with frost damage causing the surface to loosen and break up and failure through overloading of vehicles/aircraft at the top. It should be noted that minor maintenance i.e. patching provides a permanent restoration of the stability and riding quality of pavements that are affected by random areas of defective material on pavement surfaces and not continuous lengths or whole widths for that matter (Transport, 1994). The treatment process is simple and is as follows:

1. Mark out a square or a rectangle area to embrace all defective material.

2. Form the edges of the excavated area by saw cutting or planning on straight to a firm, undisturbed vertical edge. The depth of a patch excavation normally does not exceed wearing course depth.


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3. For deeper excavation, no step is required between wearing course and base course, although a minimum of a 75mm step should be made between base-course and road-base.

4. Ensure all edges are clean and trimmed and sweep clean. 5. Paint the edges of the area with hot 50 penetration bitumen. 6. Spray the base of the area with tack coat. 7. Place patching materials in a uniform layer, levelled and shaped, this

is to help maintain existing carriageway camber/cross fall following compaction. The new material must start at one end and finish at an opposing end with the material being flush with all joints, channels and projections to make it easier for a level finish, or not more than 3mm above adjoining pavement surfaces.

8. Compact all parts of the patch evenly avoiding roller marks on the surface and damage to adjacent sections to the patch. Care should be taken to ensure that no material is pushed or displaced during compaction.

9. On completion of the operation the site must be cleaned thoroughly. (Transport, 1994)

Figure 86: Flexible pavement patching procedure (Transport 1994)


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The process of major maintenance operations in the form of overlaying/resurfacing of large parts or all of an existing surface of a pavement will be considered when large sections of pavement(s) surface have been compromised (Transport, 1994). This can be due to the detection of defective material on the surface similar to that of minor maintenance only that much larger portion of the surface will have been affected, restoring skid resistance across large sections of the pavement which has been lost over time thus increasing the overall riding quality and just simply strengthening the overall pavement structure (Transport, 1994).

When resurfacing just to improve lost skid resistance to the surface of a pavement it will be sufficient to use the minimum thickness the material can be laid. However if resurfacing is governed by kerbs or drainage outlets etc. it is important that the removal of existing surfacing take place prior by using a special planer (Transport, 1994).

As the name suggests overlaying is putting something on top of another hence the application of overlaying maintenance methods will require raising up street elements such drains, gullies marker posts, telephone posts etc. to the new pavement level as the additional layer will increase the overall pavement height (Transport, 1994). When overlaying a pavement it is important to inspect the overall quality of the surface which will be overlaid. If cracks or patches are visible then it is recommended to apply surface and minor maintenance methods mentioned above prior to overlaying. Coring through the cracks may help to determine if the cracks are only in the wearing course (surface initiated) or through the full thickness of the bituminous material (Transport, 1994). In the former case, planning of the existing wearing course maybe sufficient treatment prior to overlaying. If the cracks are severe and appear in the base course also all of the existing bituminous material may have to be removed and then overlaid (Transport, 1994).

Sustainability Considerations for Constructing Flexible Pavements

When the California Bearing Ratio (CBR) of subgrade is checked to be below a certain percentage (e.g. 5%), which indicates a weak or poor quality subgrade the need for a capping layer is increased this is normally provided to reduce the effect of weak subgrade on the structural performance of the road (Engineeringcivil, 2014). It also provides a working platform for sub-base to be constructed on top in wet weather condition because the compaction of wet subgrade is difficult on site. The effect of interruption by wet weather can be reduced significantly and the progress of construction works would not be hindered (Engineeringcivil, 2014).


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Common materials for the capping layer are of the granular form such as aggregates or excavated materials from the site e.g. are crushed gravels and rock fill, all of which can be sourced locally making it a really cheap and sustainable option to strengthening weak subgrade (Hunter, 1994). This layer can be a big contributor towards sustainable design due to cheapness, recycling of waste material and transportation costs as the material will most of the time be readily available locally.

The capping layer not only serves to strengthen the subgrade, but also protects the road formation during construction. The main function of the capping layer is to provide a road to construction traffic and more importantly provides protection for the subgrade from weathering such as frost damage and wetting by insulating the subgrade (Hunter, 1994). Protection from weather damage increases the overall life span of the flexible pavement which ultimately makes it more sustainable.

The conservation and implementation of secondary and recycled materials will be considered right throughout the construction phase of the flexible pavements. This will be done in order to make the flexible pavements further sustainable while also saving money as reusing unwanted material will be a lot cheaper than other options. Types of secondary recycled materials can range from reclaimed material from road reconstruction, from residues of industrial process such as mining and from the demolition of other construction projects (Transport, 2004).

The conservation of existing pavements and the use of secondary and recycled materials helps to reduce the impact on the environment by reducing the extraction of primary aggregates and at the same time reduces the amount of waste being generated (Transport, 2004). Reusing unwanted waste material is good but care must be taken on deciding how and what to use as not all waste material can be used for all jobs. Figure 87 shows more information regarding this issue. A list of all types of material that fall under the category of potential secondary and recycled materials regarding highway works is also listed in Figure 87.


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Figure 87: Secondary and recyclable waste material (Transport, 2004)

An example of the issue stated earlier is furnace bottom ash (FBA) which can be used for the capping layer and hydraulically bound mixtures for sub-base and base but cannot be used for the unbound mixtures for sub-base and bitumen bound layers.

Noise Reduction Methods

Noise is a form of sound which in the context of transportation engineering is unwanted sound. The most common sources of unwanted sound is traffic noise which comes from traffic using a road network (Transport, 2011). However this projects main focus is the design of an urban airport thus traffic noise i.e. noise from cars using road networks is less important here hence the issues related to aircraft noise management and mitigation will be further discussed in this section.

Aircraft noise can have a disturbing effect in particular to the inhabitants in the vicinity of airports, leading to noise being a specific form of pollution (Kazda & Caves, 2000). Too much sound or one that is generated too often, in an unwanted time, place or situation is designated as noise i.e. unwanted sound (Kazda & Caves, 2000).


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Noise around airports will be controlled using three different methods. The first will be to reduce the noise at the source i.e. using up to date technology for quieter aircraft and aircraft noise certification to ensure that the available technology is employed (Kazda & Caves, 2000). The second method is will be to control the aircraft operations such that noise reduction is a key consideration. This includes things like optimization of flight procedures, distribution of movements between runways and limiting operations by type and time of day while monitoring noise levels at selected points of the airport vicinity. (Kazda & Caves, 2000). The third and final method is land use and compatibility planning around the airports, particularly with regard to urbanization zones (Kazda & Caves, 2000). Applying these three methods effectively should ensure an acceptable noise load on the inhabitants in the vicinity of airports.

Other noise reduction methods regarding design will be to use flexible pavements for all movement areas within the airport. This will include the runway, taxiway(s) and apron. The reason for this is that bituminous materials on the surface tend to be quieter than ridged concrete surfaces due to the elastic and flexible nature of bituminous materials.

The final noise mitigation action that will be taken to further help with noise mitigation is to construct a form of noise barrier(s) between the airport site and the new university student complex (south), see Figure 88 below.

Figure 88: Constructed noise barrier location on site


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The choice of material is concrete as it has multiple positive points such as it is cheaper than other options such as recycled rubber also the ease of construction of concrete embankments along with easy maintenance make it a nice option. The height of these two embankments will be 4m high and will be further backed by the application of tall dense deciduous trees such as Elm and Birch (both available in the UK) behind both of the noise embankments and all the way around the airport site. Trees can act as noise barriers though not very good but can play a major part because they are more of a psychological barrier (if u can’t see the traffic it reduces the perception of noise. Trees bring natural attractiveness while also help reduce the unattractive sight of the concrete embankments from the outside view i.e. from the locals and by-passers perspectives.

Runway Safety System

It is not uncommon for aircraft to overrun the length of a runway due to reasons such as decision to abort take-off at the last minute because of engine failure or when a pilot touches down well beyond the touchdown zone (more than 300m from threshold) (Kazda & Caves, 2000). To avoid such incidents a runway end safety area will be provided in the form of an arrestor bed which will be made of loose materials such as sand accompanied by reinforced concrete edge barriers on each side of the arrestor bed and at the end (Kazda & Caves, 2000). The loose sand is used to significantly decrease the speed of the aircraft by burying the aircrafts wheels forcing it to slow down, the barriers will serve the purpose of preventing the aircraft from swaying of the runway and toppling over (Kazda & Caves, 2000). This runway system is deemed more sustainable in comparison to a common steel barrier as recycled material may be utilised. Loose soil, used to construct the barrier, may be transported from the foundation excavations.


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Figure 89: Runway end safety precaution

Runway Drainage

Gullies will be used to remove surface water run-off from the airport runway and the hydraulic capacity of a gully determined by overall size, the number and orientation of the runway and provided watercourse area. There are many factors affecting hydraulic design which will be considered during the design process such as Manning roughness coefficient of the channel (n), design storm return periods, permissible flow widths along the kerb (Great Britain. Department of, 2000)

The accumulation of debris will be considered in order to improve the efficiency of the gully because debris is capable to reduce the hydraulic area if not cleared straight away by maintenance operations. In addition future maintenance requirements at the gully location will be considered to make sure that this activity will not compromise access in the future (Great Britain. Department of, 2000).


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Design Procedure

In this project the design manual for roads and bridges Volume 4 Section 2 Part 3 HA 102/00 will be used to design gullies and relevant formula will be used during the design process. According to the design manual the important parameter will be taken into account to determine maximum spacing for gully gratings and flow collection of gully gratings includes:

rainfall intensity I (mm/h) for a storm with a return period of 5 years, the effective catchment width draining to the kerb channel, maintenance factor ‘m’, values of the longitudinal gradient, SL, at points along the length of

the scheme, Manning roughness coefficient, n, Maximum allowable flow width against the kerb. (Great Britain.

Department of, 2000)

T-Junction Design

The airport site will be connected to Frederick road using a t-junction. As Frederick road is classed as an S2 road located in an urban environment, DMRB volume 6 section 2 part 6 suggests that a simple t-junction may be designed. The airport road was designed as a one way system allowing vehicles to enter and exit the site therefore it will be necessary to construct 2 T-junctions. The t-junction will be designed as a two lane road allowing vehicles to enter the one-way flow system and either drop persons at the terminal building entrance, or use the car park. The second lane will be primarily used for vehicles staff as the road will lead beyond the terminal building and onto the apron. A security system will be used to ensure that unwanted persons and vehicles do not access beyond the terminal building.

This report will primarily investigate the design of the t-junction connecting Frederick road to the airport however, there are a number of minor junction within the airport. An example of a minor junction would be the site road connecting to the car park. The overall car park and t-junction design has been provided on a number of AutoCAD drawings.

As the t-junction will be located on Frederick road the maximum speed limit will be 30mph (50kph). Therefore, the t-junction was designed to ensure there was suitable visibility to drivers on the road. Table 7/1, (Part 6 TD 42/95) states that a speed of 50kph should consider a distance of 70m between the centre of the airport road and Frederick road. This indicates that throughout the 70m there should be no objects such as building and structures that may affect driver visibility of the upcoming junction. The width of the two lane road was 10m which will also include a 1.0m footpath


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on both sides of the road to allow people to walk into the airport site. Therefore an individual lane was designed to be 4m wide. The design of the t-junction and location of site roads and car park have been shown on the following pages.

The car park was designed to accommodate the anticipated number of customers and staff. In addition, 10 number disabled bays have been provided on the car park adjacent to the terminal building. A zebra crossing was provided on the road between car park and terminal building to allow persons to cross the road safely. The car park envelope was 70m x 40m and contained a road system to allow vehicles to travel around the car park and select a suitable parking bay.

The main issue with the t-junction design is that there is an existing Y-junction opposite the proposed site. As the proposed t-junction will be located within the proximity of the existing junction this could significantly increase traffic on Frederick road. Therefore, it may be necessary to implement an addition traffic lighting system before the airport entrance road to reduce traffic volume at the existing Y-junction.

29.0m

Tramw

ays

REDERICK ROAD

28.7m

29.3m

1 to 11

on Forum

5 to

10


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Water Resources

Surface Water Drainage System

Surface run off is generated as a result of constructing an airport. A drainage management system will be maintained in accordance with UK building regulations. In this project all surface water will be collected and directed to a storm water management system. Grey water will then be treated and discharged into River Irwell. Storm water will be transported to an attenuation tank via a pipe system, in order to be stored and discharged into River Irwell at a specific rate. The design of the pipe system will be carried out by determining a suitable pipe diameter using the anticipated rate of flow. The pipe size will be rounded to the nearest commercially available pipe diameter, which must be bigger than the obtained pipe diameter through the calculation process. The airport was divided to six catchments and the discharge at each catchment was different. However to reduce complexity the same size of pipe will be used for every catchment, according to the total discharge.

Pipe Design

Trial 1

Total Q = 0.0484m3 (this number obtained through the calculation process of surface runoff)

Material = rigid pipe concrete will be used because concrete strong, durable and sustainable material hence approved by UK building regulations (Planning Portal, 2000).

Mannings (n) value = 0.013 (lecture notes)

Slope = 1/3000

Pipe diameter = 250mm estimated

Hydraulic radius (R) = 0.95 x 0.250 = 0.2375

Chezy roughness coefficient (C) = �

� � ��/� =

�

�.�� 0.2375�/� = 60.53

Q = A.V

Q = AC √��

Substitute into Chezy’s Equation


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Velocity (V) = C �Rxslope

(V)= 60.53 �0.2375x�

�� = 0.54m/s

Q = A.V

Q = ��

�.V

0.0484m � = ��.��

�x0.54

0.0484m � = 0.0266m3/s

Hydraulic checks

Qp = 0.0266m3/s

Qp< Qpeak

0.0266m3/s < 0.0484m �, therefore NOT OK

Trial 2

Total Q = 0.0484m3

Material = rigid pipe concrete

Manning’s (n) value = 0.013 (lecture notes)

Slope = 1/3000



Chezy’s roughness coefficient (C) = �

� � ��/� =

�

�.�� 0.285�/� = 62.4

Q = A.V

Q = AC √��


Velocity (V) = C �R x slope

(V)= 62.4 �0.285x�

�� = 0.61m/s


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Q = A.V

Q = ��

�.V

0.0484m � = ��.��

�x0.61

0.0484m � = 0.0431m3/s

Hydraulic checks

Qp = 0.0431m3/s

Qp< Qpeak

0.0431m3/s < 0.0484m �, therefore NOT OK

Trial 3

Total Q = 0.0484m3

Material = rigid pipe concrete

Mannings (n) value = 0.013 (lecture notes)

Slope = 1/3000



Chezy roughness coefficient (C) = �

� � ��/� =

�

�.�� 0.3325�/� = 64

Q = A.V

Q = AC √��


Velocity (V) = C �Rxslope

(V)= 64 �0.3325x�

�� = 0.67m/s

Q = A.V

Q = ��

�.V


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0.0484m � = ��.��

�x0.67

0.0484m � = 0.0645m3/s

Hydraulic checks

Qp = 0.0645m3/s

Qp> Qpeak

0.0645m3/s > 0.0484m �, therefore OK

Water Supply System

The main water line of this project will be connected to the nearest junction of the main water distribution network. This process will be carried out through the application to the water company in order to decide which connection point needs to be used. United Utilities Water plc provided design guidance for water mains and services on new development, the process illustrated in the chart as shown in Figure 90.

Figure 90: Requisition quotation service levels and flow chart (United Utilities, 2012)

For this project all potential routes have been taken into consideration in order to identify the most appropriate pipe connection for new water mains. The whole life costs arising due to the construction, operation, maintenance and eventual de-commissioning will be taken into account.


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Furthermore consideration also will be given to make sure that all existing property are completely utilised.

For the airport the assumed connection point will exist in Fredrick Road and the calculation process will be based on this assumption. However if this is not achievable then an alternative junction will be provided adjacent to the University of Salford campus. Both possibilities have been considered due to existing locations. If a pipe in connected adjacent to the airport this may reduce installation costs and reduce the environmental impacts.

To select an appropriate route for this project the following will be investigated accordingly:

Existing ground conditions such as rocks and groundwater,

Consideration to water contamination

Consider existing and future land use,

Land ownership as it affects the company’s powers to install and

operate apparatus.

Agreement to lead-time where it is essential to serve notices

Consider traffic management,

Possible environmental impact of the works

Accessibility for safe construction as well as future maintenance of

the property

Consideration to other utilities

Consider pipeline failure and its consequences

Consider the operation of pressures at key points

Design Calculation

Water Demand

1. Estimation of water demand for terminal building = 2.63 X10-5m3/s

2. Estimation of fire flow demand for terminal building = 0.027m3/s

3. Estimation of fire flow demand for Apron = 0.052m3/s 4. Estimation of fire flow demand for Airport Hangar = 0.027m3/s

Total estimated water demand for the project:

(Q) = 2.63 X10-5m3/s+0.027m3/+ 0.052m3/s+0.027m3/s = 0.109m3/s

(Those figures were obtained from the estimation of water demand and fire flow demand in Feasibility report)


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Pressure Head

The minimum pressure head for terminal building is 8m hence the building 8m height. The minimum pressure head for fire flow is 20m for three hours (Fire Chiefs Online).

Velocity

According to the United Utilities Water plc design guidance, the optimum design velocity of flow for the system is 1.0 m/s, with minimum and maximum design parameters of 0.2 m/s to 1.5 m/s respectively. For this project the optimum design velocity of flow 1.0 m/s will be used.

Pipe Design

Pipe length =226m

Velocity=1.0m/s

Total (Q) = 0.109m3/s

Roughness coefficient plastic pipe (C) = 150

Pipe size diameter available in market place includes 25mm, 32mm,63mm,90mm,110mm,160mm, 225mm,315mm (Design guidance for water mains and services on new development sites).

Assume 30m pressure head at the junction and not difference in head elevation between the junction and the site.

Q=V.A

A=��

0.109=V. ��

Using trial and errors method to select right size of pipe diameter

Trial 1

Using 110mm pipe diameter

0.109=1.0. �.0.055�

0.109=0.0095


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Trial 2


0.109=1.0. �.0.08�

0.109=0.02

Trial 3


0.109=1.0. �.0.16�

0.109 m3/s =0.10 m3/s

This diameter will be ok and will be used for all sites to reduce costs at the connection point and to reduce minor losses.

Calculating head loss due to the friction in the pipe using Hazen-Williams equation and minor losses neglected since does not affect too much as it is no very long distance.

� =��.��×�×��.��

��.��× ��.��

� =10.353× 226× 0.109�.��

150�.�� × 0.315�.��= 1.0135�

Pressure head at junction – head loss = head at site

30 – 1.035 = 28.98 therefore ok


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Flooding

Types of studies needs to be carried out to assess the vulnerability of the site to surface water flooding

Surface water flooding happen as a result of high intensity rainfall, flooding from groundwater, sewer flooding, flooding from open-channel and over land flow. Flooding is mainly happening due to the high intensity of rainfall, high water level and deficiency in the capacity of drainage networks. Flooding has a very negative effect on the economy, environment and people. For instance floods can destroy infrastructure such as bridges and road as well as houses and other property. The environmental effect of floods includes taking chemical and hazardous substances in to the water body consequently, effects aquatic life. Furthermore people injure and die as a result flash floods. Flood Risk Regulations (2009) for England and Wales which came into force on 10 December 2009 in order to bring the Environment Agency, district Councils and Unitary Authorities simultaneously in the company of water companies to manage flood risks from all sources hence decrease the result of flooding on environment, human health, economic and cultural legacy.

To assess the vulnerability of the airport project to surface water flooding different types of studies need to be taken into consideration. These studies are very important to prevent or reduce the effect of potential flooding. Surface water management plan (SWMP) guidance outlines the preferred surface water management strategy study. The intention of a SWMP is create sustainable surface water management decisions base of evidence and risk at the same time as taking climate change into account. The framework for undertaking a SWMP indicated in Figure 91.


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Figure 91: Framework for undertaking a SWMP study (Defra, 2010)

There four types of studies proposed by Defra to assess the vulnerability of the area for flooding include a strategic assessment, an intermediate assessment, a detailed assessment and map and communicate risk. Each of those studies uses certain types of information to identify areas that vulnerable to surface water flooding. For airport project these studies will be used as part of: Strategic assessment, where surface water mapping be capable to discover the location of the airport project in the areas that susceptible to surface water flooding. Intermediate assessment, where output from the strategic assessment is improved along with consideration is given to whether new project drained to an area of existing surface water flooding (‘hotspots’).


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Detailed assessment, which must consider comprehensively how proposed new project is an able to decrease existing surface water flood threats as part of the future scenario. In order to assess the vulnerability of airport project for flooding and to reduce existing surface water flood risk following principal will be considered:

1. Historic flood incident data: This is very significant sources of

information in order to identify flood hotspots. This information

includes area of flooding has occurred in the past, source of the

flooding, the depth, the severity and frequency. In order to achieve

those information the entire partners should hold information on flood

incident data such as local authority, environmental agency an

water and sewerage companies as well as stakeholders will be

consulted to provide further knowledge and information. However,

historical data are only register flooding incidents therefore do not

represent a complete assessment of the entire consequences and

likelihoods of flooding incident. Furthermore historical data cannot

identify all locations that susceptible for flooding for that reason it is

likely that areas at low probability and high consequence may

perhaps not have historical records of flooding as a result of

infrequency flood events. Likewise, the historical flood incident data

possibly will not be a full representation of locations that have

flooded in the past.

2. Using Environment Agency national susceptibility to surface water

flood maps. This is also important to reduce the potential flooding for

new development because these maps present an indication of

areas which are more vulnerable to flood first, flood deepest and

flood more often. These maps will be obtained from Local Resilience

Forums and local planning authorities. Furthermore these maps

capable to be used to assist prioritise areas requiring an additional

comprehensive assessment of surface water flooding.

3. Site visits and surveys: This is also very important component to assess

the vulnerability of the site for flooding since they considerably help

to increase an understanding of the possible catchment reaction to

rainfall and locations which may perhaps affected by surface water

flooding.

4. Modelling approach: This is also essential for predicting surface water

flooding which will take place both now and in the future for a

variety of event probabilities as well as testing different mitigation

measures in order to spot the most cost beneficial option. However


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to select an suitable modelling approach a number of considerations

will be taken into account and should be made in the company of

skilled modelers and analysts.

Design Foul Sewer In this project foul sewer will be designed for terminal building because restaurant and all ladies and gents toilets located in this part of the project. For design the foul sewer, the practical guidance with respect to guidance requirement of schedule 1 to and regulation 7 of the building regulations 2000 (SI 2000/2531) for England and Wales will be used in this project which known as an approved document H for drainage and waste disposal. The provisions of section 1 of the document are suitable for domestic and nondomestic building which will be used for this project (Planningportal.gov.uk, 2015).

Design Consideration

Traps

Traps are curved or S-shape of pipe under a drain which is very vital component of drainage system because prevents foul air from the system entering the building. When water flows from the sink in the company of enough pressure to go and out through the trap to drain pipes, sufficient water remain in the trap afterward in order to form a seal hence prevent sewer gas entering to the building. Trap will be provided for all point of discharge of the system apart from toilets because toilets are self-trapped hence no needs an additional trap at the drain (Club, 2015). The approved document provided the size of trap diameter and depth of seal of water in millimetre (mm) for all type of discharge points as indicated in Table 17 which will be practised for designing drainage system in this project (Planningportal.gov.uk, 2015). Table 17: Minimum trap sizes and seal depths

Appliance Diameter of the traps (mm) Depth of seal (mm) of water

Wash basin 32 75

Urinal bowl 40 75

Sink 40 75

Toilet 100 50


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Discharge Pipe Design

In terminal building toilet will be provided in both stories for ladies and gents. In each floor five cubical and two urinals will be provided for gents and seven toilets for ladies. The toilets in each floor for ladies and gents will be connected separately to another pipe known as branch discharge pipe. To prevent cross flow and blockage opposite branch connection will be avoided as well as avoid bending if possible or if not large radius will be provide. The size of branches is dependent on the number of connections, if branch pipes serving a single appliance the diameter will be the same as the appliance trap. Similar to the toilets all sinks and the wash basin taps will be connected to branch discharge pipe. In order to avoid the need for ventilation of the pipe work, the pipe lengths will restricted according to the approval document H, however ventilation will be provide for branch that over 15m length or have 5 bends (Planningportal.gov.uk, 2015).

Since in each floor seven cubical provided for ladies, they will be connected to a single branch discharge, in addition for gents 5 cubical and 2 urinals provided in each floor will be connected to one discharge pipe. With regard to wash basin taps, as mention earlier 4 taps provide in each floor for ladies and gents and will be connected separately to a single discharge pipe. Furthermore 10 sinks will be provided in the restaurant and will be divided between two discharge pipes in order to reduce the probability of blockage. The maximum number of appliance to be connected discharge pipe, type of appliance, maximum length and minimum size of the pipe summarised from the approved document and will be shown Table 18. Any discharge branches exceed the maximum length of branches pipe will be ventilated by a branch ventilating pipe to external air (Planningportal.gov.uk, 2015).

Table 18: Common branch discharge pipe (unventilated)

Appliance Maximum number to be connected

Maximum length of branch pipe (m)

Minmum size of pipe (mm)

Wash basin 4 4.0 50

Sink 5 15 100

Toilet& Urinal bowl 8 15 100

Design Discharge Stacks

Discharge stacks will be designed to carry waste water from the out let of discharge pipe to the treatment plant or to the public sewer. In this project two types of discharge stacks will be designed for grey water and black water and will not be mixed together. According to the approval document H, the size of stack depends on the maximum capacity in litter per second and it is also suggested that the diameter of the stack must not less than the size of discharge pipe. Base of that the diameter of the stack will be 100mm for all type of waste water (Planningportal.gov.uk, 2015).


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Pumping Installation

Removing waste water from one point to another point will be carry out by gravity by providing sufficient slop. However if this is not practicable at some points pumping installation will be provided to create sufficient pressure hence push the waste water (Planningportal.gov.uk, 2015).

Material for Pipes and Joints

With reference to British Standard Specification flexible joints will be provided for an appropriate pipe material (Planningportal.gov.uk, 2015). Polyvinyl chloride PVC flexible pipe material will be used for piping system and the advantage of PVC material is light weight, easy to install, durable material as it is resistant to weathering, chemical rotting, and corrosion (Pvcconstruct.org, 2015). In order to protect the pipe form excessive loading and breakage, the pipe will be laid on granular material of 100mm and will be covered by 100mm free granular material to protect the pipe from deformation and 200 backfilling material. In general the choice of bedding and backfilling material is dependent on the depth and width of the trenches (Planningportal.gov.uk, 2015).

Sustainability

Waste water from wash basin taps and sink which known as grey water will be recycled in this project. However the waste water from toilets and urinal which known as black water will discharged into public sewer system because recycling black water very expensive and also contains pathogens hence cause a health problems. There are many methods available to grey water such as filtration, wetland, disinfection and fluoridation biological infiltration, mechanical filtration and etc. In this project fast sand infiltration method will be used because simple, easy and cost effective. The sand filter system is made up of a thin layer of gravel on top of a much thicker layer of sand inside of a waterproof container. The water will be passed through the sand being thinly filtered while it goes before come out at the bottom. The filtered water at the bottom sand layer is having a better quality in comparison to the top layer. After completing filtration process and treated with chemicals to destroy all microorganisms the grey water will be pumped from source back to use for the toilet and gardening via a header tank (Reuk.co.uk, 2015). The location of treatment plant will be below the driveway near the River Irwell as indicated in Figure 92.


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Figure 92: Location of attenuation tank on site

Attenuation tank

According to the design brief the maximum allowable run-off from the site is 4.5 l/s/Ha which will outfall to the River Irwell at a single point. With reference to discharge calculation in this project run-off exceed the maximum allowable which is 8.540 l/s/Ha and will be stored in attenuation tank and released later. Base of that 4.04 l/s/Ha will be stored in the attenuation tank. The attenuation tank will designed to collect run-off for six hours during the heavy rain and to make sure that detention volume is available for the next storm event; the tank will be designed to empty within approximately 4 hours after a storm event (PUB, 2015). In this project storm water in the attenuation tank will be discharged by gravity so the head difference will be provided between the water in the attenuation tank and the receiving drain to discharge the collected water in the attenuation tank. The discharge rate from this system will be regulated by a flow control device such as an orifice.

Attenuation Tank Specification

With reference to discharge calculation 4.04 l/s of run-off exceed the maximum allowable. For the duration of six hours the volume of water will be (4.04x60 seconds x 60 minutes x 6hourse = 87264l litters. ANUA provide the design specification of the tank in terms of capacity (litter), diameter (m) and length (m) as indicated in Table 19. For this project a tank with 2.64m diameter and 18.9m length will be provided because it has a capacity to store 90000 litters (Anuainternational.com, 2015).


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Table 19: Storm water attenuation tank typical specification (Anuainternational.com, 2015)

Capacity (Litres) Diameter (m) Length (m)

36000 2.64 7.8

40000 2.64 8.6

45000 2.64 9.6

50000 2.64 10.7

54000 2.64 11.5

70000 2.64 14.7

80000 2.64 16.8

90000 2.64 18.9

100000 2.64 20.9

Access Requirements

The detention tank system will be designed to allow workforce and equipment access to different parts of the tank for maintenance purpose such as base of the tank as well as the inlet and outlet structures (PUB, 2015).

Inspections

Inspections will be carried out once every month especially after major storm events. The attenuation tank systems will be inspected for the physical condition of the tank such as structural damage, stagnant water, clogging at trash racks or inlet and outlet structures and sedimentation (PUB, 2015).

Construction material of the attenuation tank

For the attenuation tank polyvinyl chloride PVC will be used and the benefit of such a material is abrasion resistance, light weight, good mechanical strength and toughness. It is also easy to install because capable to form any shape, welded and joined easily in a different styles as well as light weight hence reduces manual handling difficulties. Moreover PVC is durable material as it is resistant to weathering, chemical rotting, and corrosion (Pvcconstruct.org, 2015).

Location of the tank

Based on the site layout the best location for the attenuation tank will be underground below the driveway near the River Irwell. In view of the fact that there is adequate elevation difference between the ground level of the site and the discharge point to the River Irwell as well as the close to the most impervious area of the project such as car park and terminal building as shown in the Figure 92. The attenuation tank will be placed under the ground in order to collect water easily and discharge it by gravity as the down side of the tank have a lower elevation. The drainage system will be connected to the tank from all catchment by pipe system.


204

Sustainability

In this project the airport apron and the car park produce harmful ingredients as a result of the spillage of grease, oil and other substances which is not environmentally friendly. Also using chemical substances in the winter for de-icing aircrafts effect the quality of water by mixed to surface water runoff which will be discharged into the River Irwell. In order to overcome this problem bypass oil separators will be installed in apron, car park and airport hangar to separate pollutant and reduce the risk water contamination. The oil separator will be installed within surface water drainage systems with the intention of protect attenuation tank by removing pollutants from surface water run-off before entering into the tank (Klargester.com, 2015).

Critique

The purpose of designing a pipe system is to supply water to the site with adequate pressure and velocity. It is important to design an appropriate size of pipe diameters for the reason that providing small or big size directly affects the system performance. For instance, pressure reduces by reducing pipe diameter and velocity will increase by decreasing pipe diameter. Therefore it is very important to select the right size pipe diameter. Pipe material also very essential to energy loss and the design life of the system. It was observed that the cost of the pipe system will depend on the system layout, material, and size of the building. In addition, any fault in system will be expensive and time consuming therefore it is vital to consider all aspect of the design.

During the design it was identified that storm water runoff would impact both water quality and water quantity problems. In this project storm water collects and carries a number of pollutants from oil and grease spillage, sediments, and other chemicals substance. These chemicals may travel into River Irwell and some of these contaminants may cause problems to the water quality and make the purification process difficult for a water company. Storm water runoff may also cause a problem during flooding as a result of converting vegetation area to impervious area. To prevent or reduce storm water runoff a number of methods may have been implemented such as storm water wetlands, wet ponds, infiltration devices, and attenuation tanks. In this project an oil separator was used to separate pollutants from the runoff and improve sustainability measures. In this project an attenuation tank was considered to collect excessive run-off water. The collected water would then be discharged later to River Irwell and underlying strata. This method was deemed suitable because it was more practical and the most effective in comparison to other methods.


205

A pipe network was designed to transport surface water run-off to the attenuation tank. A foul sewer was designed for carrying off drainage water and waste matter from the terminal building to the treatment plant. It is important to maintain self-cleansing velocity to make sure particles do not accumulate in the pipe and cause blockage. In order to design a successful sewer system peak dry weather conditions will be considered, in addition to a downhill gradient. A gradient will be provided along the length of the sewer in order to maintain self-cleansing flows, for those reason deep excavations will be needed. However when a downhill grade is not achievable pumping station will be provided.

Conclusion In conclusion, detailed estimation of water demand for the whole site was provided for the terminal building by considering peak flow and using fixture value methods including future projections and diurnal variations. The locations of the site that are vulnerable to fire accidents was identified such terminal building, apron and runway and provisions were made for fire-flow demand by using National Fire Academy (NFA) formula for fire flow demand calculation. In addition, a water supply system was designed for the site to provide the required quantity of water at sufficient pressure. The Hazen-William equation was used to calculate energy loss in the pipe and PVC material was purposed for the pipe system. With regards to surface water, the types of studies were performed to assess the vulnerability of the site to surface water flooding. The attenuation tank was designed for surface water collection and storage. In addition, sustainability measures where considered to reduce surface water pollution. Therefore, an oil separator in the car park and apron was required. The surface water drainage network was designed using Chezy’s equation and a concrete pipe along with designing sewage network for the terminal building.


206

HEC-RAS Coursework As part of the Water Resources module it was a requirement to complete a document on the analysis of an open channel using on HEC-RAS. As three members of Group 601 are currently studying this module, three individual pieces of coursework have been included within document. The following pages include the three individual HEC-RAS documents. The documents were completed by:

- Sam Cherrington - Ari Aziz Abubaker - Dilawar Ali

T H E U N I V E R S I T Y O F S A L F O R D

S C H O O L O F C O M P U T I N G , S C I E N C E A N D


LEVEL 6 INTEGRATED

DESIGN EXERCISE

WATER RESOURCES

HEC-RAS COURSEWORK

Prepared For:

Dr. Prasad Tumula

Module Lecturer

Prepared By:

Sam Cherrington

@00268184

19.01.15

S.Cherrington Water Resources

ii

Contents

Contents.............................................................................................................................................. ii List of Figures ................................................................................................................................... iii List of Tables ..................................................................................................................................... iii Introduction to the Report .................................................................................................................. 4

Executive Summary ....................................................................................................................... 4 Introduction .................................................................................................................................... 4 Aims and Objectives ...................................................................................................................... 4

Theory ................................................................................................................................................ 5 Results ................................................................................................................................................ 8

Flow Profile 1 (14m³/s) .................................................................................................................. 8 Flow Profile 2 (25m³/s) ................................................................................................................ 13

Discussion ........................................................................................................................................ 19 Conclusion........................................................................................................................................ 19 References ........................................................................................................................................ 21


iii

List of Figures

Figure 1: Illustration of energy equation for water surface (Brunner, 2010) ....................... 5 Figure 2: Plot of water surface profile for flow profile 1 ..................................................... 8 Figure 3: Graph showing the change in velocity in river profile .......................................... 9 Figure 4: Cross section of river station 1200 ...................................................................... 10 Figure 5: Cross section of river station 900 ........................................................................ 11

Figure 6: Cross section of river station 600 ........................................................................ 12 Figure 7: Cross section of river station 100 ........................................................................ 12 Figure 8: Plot of water surface profile for flow profile 2 ................................................... 13

Figure 9: Graph showing the change in velocity in river profile ....................................... 14 Figure 10: Cross section of river station 1200 ................................................................... 15 Figure 11: Cross section of river station 900 ..................................................................... 16 Figure 12: Cross section of river station 600 ..................................................................... 17

Figure 13: Cross section of river station 100 ..................................................................... 18

List of Tables

Table 1: Recorded data from flow profile 1.......................................................................... 8

Table 2: Recorded data from flow profile 2........................................................................ 13


4

Introduction to the Report

Executive Summary

As part of the Water Resources module it was a requirement to complete a steady-state

analysis of a river model using the programme HEC-RAS. The river model was computed

and an investigation was be undertaken to research the behaviour of the channel under two

different flow profiles.

Introduction

CEIWR is an abbreviation for ‘Corps of engineers – institute for water resources’. HEC is

an abbreviation for hydraulic engineering centre. CEIWR-HEC was founded in 1964 by

USACE (U.S. Army Corps of Engineers) to improve water resources planning and

management. CEIWR-HEC was primarily designed to provide technical assistance to

USACE and to carry out research. CEIWR-HEC developed a number of software

including HEC-RAS, HEC-HMS, and HEC-WAT. This project will assess the suitability

of a river model using the software HEC-RAS.

‘HEC-RAS is an integrated system of software, designed for interactive use in a multi-

tasking, multi-user network environment’ (Brunner, 2010, p. 12). For this particular project

HEC-RAS will be utilised to perform a steady-state analysis on a chosen river reach model

to calculate channel properties. (Brunner, 2010) suggests that HEC-RAS provides the user

with a number of one-dimensional analysis tools including: steady flow simulation,

unsteady flow simulation, moveable boundary sediment analysis, and water quality

analysis. In addition, HEC-RAS can be used to determine the effects of certain structures

including bridges, spillways, and culverts. The steady-state analysis will record data in the

form of tables and graphs which are easily interpreted. The channel flow state can be

determined using a profile plot of channel distance against Froude number (Fr).

Aims and Objectives

The aim of the experiment was to analyse the behaviour of an open flow channel through

steady-state analysis. In order to achieve this aim the following objectives where

formulated:


5

To learn how to operate the software HEC-RAS in order to complete the steady-

state analysis.

To complete the analysis using two different flow profiles and to present the

collected data in the form of graphs and tables.

To assess the accuracy and suitability of the experiment in addition to a

recommendation against the reliability of the river model against flooding.

Theory

HEC-RAS is a programme that allows the user to input cross sectional data for a channel.

When performing the steady state analysis HEC-RAS will determine the cross section

properties of channel which includes: area of cross section, wetted perimeter, top width,

and hydraulic depth. The hydraulic depth is calculated to determine the potential of a

channel flooding. Therefore, if the hydraulic depth is higher than the river depth the river

will suffer from flooding.

As the river reach is composed from a number of channels the energy equation is used to

calculate the water surface profile. The energy equation used is formulated as:

𝑍2 + 𝑌2 +𝑎2𝑉2

2

2𝑔= 𝑍1 + 𝑌1 +

𝑎1𝑉12

2𝑔+ ℎ𝑒 (Brunner, 2010, pp. 2-2)

Where:

Z = elevation of main channel

Y = depth of water at cross section

α = velocity weighting coefficient

ℎ𝑒 = energy head loss. (Brunner, 2010, p. 18)

Figure 1: Illustration of energy equation for water surface (Brunner, 2010, pp. 2-3)


6

The energy equation is used to calculate the water surface profile for sub-critical and

super-critical flow. If the river surface passes through critical depth it is assumed that the

water is within a rapidly varying flow situation, therefore the energy equation cannot be

utilised. As the energy equation can only be used for gradually varied flow the momentum

equation will be used. (Brunner, 2010) suggests that the momentum equation can be

applied when a hydraulic jump forms within a channel.

The momentum equation is calculated using Newton’s second law of motion:

∑ 𝑓𝑥 = 𝑚. 𝑎 (Brunner, 2010, pp. 2-16)

Where:

m = mass

a = acceleration

Through using Newton’s second law of motion the momentum equation is formulated as:

𝑃2 − 𝑃1 + 𝑊𝑥 − 𝐹𝑓 = 𝑄𝜌∆𝑉𝑥 (Brunner, 2010, pp. 2-16)

Where:

P = Hydraulic Pressure

Wx = Force due to weight of water

𝐹𝑓 = Force due to external friction loss

Q = Discharge

𝜌 = Density of water

∆𝑉𝑥 = Change in velocity from point 2 to point 1.

Manning’s equation is used to calculate discharge (Q) within a channel. Manning’s

equation is formulated as:

𝑄 = 𝐾𝑆𝑓1/2

(Brunner, 2010, pp. 2-4)

Where:

𝐾 =1.486

𝑛𝐴𝑅2/3 (Brunner, 2010, pp. 2-4)

Sf = Frictional Slope

K = Conveyance for section


7

The river model consist of a trapezoidal channel. The properties of the trapezoidal channel

can be calculated using the following formulae:

𝐴𝑟𝑒𝑎 𝑜𝑓 𝑐𝑟𝑜𝑠𝑠 𝑠𝑒𝑐𝑡𝑖𝑜𝑛 (𝐴) = 𝐵𝑑 + 𝑧𝑑2

𝑊𝑒𝑡𝑡𝑒𝑑 𝑃𝑒𝑟𝑖𝑚𝑒𝑡𝑒𝑟 (𝑃) = 𝐵 + 2𝑑√1 + 𝑧2

𝑇𝑜𝑝 𝑊𝑖𝑑𝑡ℎ (𝑇) = 𝐵 + 2𝑧𝑑

𝐻𝑦𝑑𝑟𝑎𝑢𝑙𝑖𝑐 𝐷𝑒𝑝𝑡ℎ (𝐷) =𝐴𝑟𝑒𝑎 𝑜𝑓 𝐶𝑟𝑜𝑠𝑠 𝑆𝑒𝑐𝑡𝑖𝑜𝑛 (𝐴)

𝑇𝑜𝑝 𝑊𝑖𝑑𝑡ℎ (𝑇) (𝑚)

𝐻𝑦𝑑𝑟𝑎𝑢𝑙𝑖𝑐 𝑅𝑎𝑑𝑖𝑢𝑠 (𝑅) =𝐴𝑟𝑒𝑎 𝑜𝑓 𝐶𝑟𝑜𝑠𝑠 𝑆𝑒𝑐𝑡𝑖𝑜𝑛 (𝐴)

𝑊𝑒𝑡𝑡𝑒𝑑 𝑃𝑒𝑟𝑖𝑚𝑒𝑡𝑒𝑟 (𝑃) (𝑚)

𝐹𝑟𝑜𝑢𝑑𝑒 𝑁𝑢𝑚𝑏𝑒𝑟 (𝐹𝑟) =𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 (𝑉)

√𝑔.𝐷

The Froude number is used to determine the flow state with an open flow channel. The

characteristic flow state is determine by:

Fr = 1 (critical flow)

Fr > 1 (supercritical flow)

Fr < 1 (subcritical flow)


8

Results

Flow Profile 1 (14m³/s)

Table 1: Recorded data from flow profile 1

Flow Profile 1 – 14m³/s

River

Station

Flow

Area (A)

(m²)

Wetted

Perimeter (P)

(m)

Top

Width (T)

(m)

Hydraulic

Depth (D)

(m)

Hydraulic

Radius (R)

(m)

1200 21.44 27.28 27.05 0.79 0.79

900 28.93 29.42 29.12 0.99 0.98

600 31.16 38.45 38.29 0.81 0.81

100 28.52 29.70 29.42 0.97 0.96

Figure 2: Plot of water surface profile for flow profile 1

The water surface profile indicates that there is an increase of 0.50m in water level

between river stations 1200-100 (Figure 2). The overall length of the river reach is deemed

to be 335m. Therefore, as the water elevation increased by 0.50m over a length of 335m

the flow state is deemed sub-critical. (Figure 2) indicates the maximum velocity of flow

profile 1 is 0.65m/s. Hence, in order to determine if the flow state is sub-critical the Froude

number (Fr) is calculated.

𝐹𝑟𝑜𝑢𝑑𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 (𝐹𝑟) =0.65

√9.81×0.89= 0.233


9

The hydraulic depth was calculated (Table 1) and an average value of 0.89m was

determined by an average of the four depths. As the Froude number was less than 1.0 this

indicated that the flow state in the channel was sub-critical.

Figure 3: Graph showing the change in velocity in river profile

The velocity in the channel varied from 0.49m/s to 0.65m/s over a distance of 335m

(Figure 3). The change of velocity within the river may have occurred due to the change in

elevation of the channel. The highest elevation at river station 1 was 180.1m, in

comparison to river station 1200 which had an elevation of 180.7m. Furthermore, the

change in velocity within the river may have arisen due to the change in top width of the

channel, due to alterations in the breadth and gradient.


10

Figure 4: Cross section of river station 1200

From the cross section (Figure 4) it is clear that flooding within the channel would not

occur in flow profile 1. The cross section indicates that with a discharge of 14m³/s the

hydraulic depth within the channel was 0.79m (Table 1). The depth of the river was 6.50m

(180.7m-174.2m) therefore the river would have to increase its water elevation by an

addition 5.70m for flooding to occur. This river station has been deemed to be very

effective against the possibility of flooding, when a discharge of 14m³/s occurs.


11


The cross section (Figure 5) for river station 900 shows that the channel is not susceptible

to flooding. The hydraulic depth of the channel is 0.98 (Table 1) when the discharge is

14m³/s. The change in hydraulic depth between river station 1200 and 900 is calculated as

0.20m. It is assumed that this is caused by the change in elevation between the two river

stations. The steady state analysis data for each individual cross section was tabulated

(Table 1). The river channel has been deemed to be very effective against the occurrence of

flooding. The depth of the channel is 3.0m which indicates that in order for a flooding of

the channel to occur, the water elevation must increase by approximately 2.0m.


12


The cross section for river station 600 (Figure 6) indicates that channel is not liable to

flooding. The hydraulic depth of the channel has been calculated to be 0.81m. For flooding

in the channel to occur the water elevation must increase by 1.70m, with a discharge of

14m³/s. Therefore, the channel is effective against the possibility of flooding.



13

The cross section (Figure 7) indicates that the channel is not susceptible flooding as the

hydraulic depth has been calculated as 0.97m. The hydraulic depth is greater than that of

river station 600. This may be due to river station 100 being located at the end of the reach,

and water will always flow downstream.

Flow Profile 2 (25m³/s)

Table 2: Recorded data from flow profile 2

Flow Profile 2 – 25m³/s

River

Station

Flow

Area

(m²)

Wetted

Perimeter

(m)

Top

Width

(m)

Hydraulic

Depth

(m)

Hydraulic

Radius

(m)

1200 126.04 40.67 230.14 3.15 3.09

900 138.03 40.67 237.82 3.45 3.39

600 193.64 60.39 236.18 3.23 3.21

100 141.51 40.59 237.00 3.54 3.49

Figure 8: Plot of water surface profile for flow profile 2

The water surface profile for flow profile 2 indicates that there is a change in elevation of

0.50m throughout the channel. The length of the river reach has been deemed to be 335m.

The worst case velocity within the channel has been calculated to be 0.16m/s (Figure 8)


14

which indicates that the flow state in the channel is sub-critical. In order to determine if the

flow state is sub-critical the Froude number (Fr) is calculated:

𝐹𝑟𝑜𝑢𝑑𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 (𝐹𝑟) =0.21

√9.81×3.34= 0.015

Therefore, as the Froude number is less than 1.0, this indicates that the flow state within

the channel is sub-critical.

Figure 9: Graph showing the change in velocity in river reach

The velocity in the channel varied from 0.10m/s to 0.16m/s with a discharge of 25m³/s.

The velocity has been deemed to be laminar flow which indicates that the flow state is sub-

critical. The change in velocity may have been caused by a change in elevation from river

station 1200-100. Furthermore, there the velocity in river station 100 is higher than river

station 600 which is unexpected as river station 100 is located furthest downstream. It is

suggested that the decrease in velocity at river station 600 is due to its greater cross

sectional area, compared to river station 100 (Table 2).

(Figure 9) indicates that the highest velocity is present within the river channel through the

river reach. There is very low river velocity present in the left and right banks. (Figure 9)

provides an early indication that flooding does occur as water velocity is present on both

banks, indicating that water is present at the floodplains.


15


The cross section for river station 1200 (Figure 10) indicates that the potential for flooding

is higher as the discharge is increased. In comparison to flow profile 1, which has a

discharge of 14m³/s, the hydraulic depth in flow profile 2 is far greater. As indicated in

(Figure 9) the water elevation will submerge the left and right floodplain or run-off areas.

As the run-off areas are submerged the flooding potential is increased. However, the

hydraulic depth of channel is 3.15m which is less than 6.50m (channel depth) and this

indicates that the river is not susceptible to flooding.


16


The cross section for river station 900 (Figure 11) indicates that the floodplains are liable

to flooding, with a discharge of 25m³/s. The floodplains within the river are submerged

however, the hydraulic depth, calculated to be 3.45m (Table 2), is less than the depth of the

entire river. If discharge in the river is increased then there may be an increased risk of

river flooding. Furthermore, climatological changes may induce an increase in water

elevation resulting in flooding of the channel. The river cross section highlights that the

channel will flood when a 25m³/s is only considered.


17


The cross section (Figure 12) provides a visual representation of the water elevation level

for river station 600. The hydraulic depth of the river station has been calculated as 3.23m

(Table 2) which is smaller than river station 100. This may be due to the change in cross

section area of the channel.

The cross section indicates that flooding will only occur on the floodplain as both river

banks are submerged. If the water elevation was to remain at the current level it may affect

the condition of the river, as the banks may be eroded creating a wider channel.

If flooding was to occur in this channel it may result in higher flow velocities which may

affect wildlife who utilise the river for habitats and vegetation. Furthermore, if flooding

was to occur at a particular station it will increase the likelihood that an additional river

station downstream will flood.


18


The cross section (Figure 13) for river station 100 indicates that flooding of the channel

will occur as the hydraulic depth is greater than the top of channel elevation (176.5m). The

hydraulic depth is calculated as 3.54m (Table 2) and the depth of the river cross section is

6.40m. However, similar to river station 600 the floodplains will be submerged, which will

require assessment. As the floodplains are submerged when a discharge of 25m³/s is

utilised it can be assumed that any occurrences of meteorological changes may cause the

channel to flood. Such events may include heavy rain and/or snow fall, in which over a

small time period, may increase the water elevation level of the channel, resulting in excess

water travelling over the river banks.


19

Discussion

The adequacy of the river model is dependent on a number of key extents. This may

include the location of the river model and if the particular climate zone is prone to intense

rainfall. Furthermore, if the river model is located with an urban environment, surrounded

by housing and infrastructure, it may be necessary to increase the depth of the channel, or

the cross section dimensions, to reduce the potential for flooding to occur on floodplains.

Flooding could have a negative effect on existing housing and infrastructure as water may

saturate existing soils where concrete foundations are located. The excess water within

soil, caused by a flood, may corrode the concrete foundation over a long period of time.

Finally, the accuracy of Manning’s ‘n’ value would affect the results of the steady-state

analysis. Manning’s ‘n’ value varied from 0.035-0.070 which indicates that the channel is

constructed with materials that provides high amounts of frictional resistance. As lined or

constructed channels, consisting primarily from concrete, with a Manning’s ‘n’ value

varying from 0.010-0.035, it is possible that the river model is constructed from vegetation

and loose material. Therefore, to increase the efficiency of the channel it may be

appropriate to construct a concrete or cement lined trapezoidal channel. However, this may

a negative impact as velocity within the river may increase due to less frictional resistance.

Conclusion

After inputting the cross section data for the river model into HEC-RAS a steady-state

analysis was performed. The steady-state analysis was used to calculate the river properties

during two different flow profiles. The first flow profile included a 14m³/s discharge in

addition to a boundary condition of 175m, which represented the known water surface

elevation. The boundary condition indicated the maximum level for water elevation in this

particular flow profile. The second flow profile consisted of a 25m³/s discharge with a

boundary condition of 178m.

Once the steady-state analysis had been completed using flow profile 1 it was clear that the

trapezoidal channel would not be susceptible to flooding. The maximum hydraulic depth

(0.99m) occurred at river station 900 (Table 1). The cross sectional diagrams indicated the

water elevation level with a particular river station and it was clear that no flooding would


20

occur. The left and right floodplains for every river station where not susceptible to

flooding, therefore the river channel model was suitable and effective.

Flow profile 2 included an increased discharge of 25m³/s in addition to a known boundary

condition of 178m. After the steady-state analysis had been completed, imposing flow

profile 2, it was observed that floodplains would be liable to flooding. The trapezoidal

channel would not be prone to flooding as the water elevation level was below the highest

boundary levels, at each river station. However, if any additional climatological changes

where induced, in addition to the 25m³/s discharge, the suitability of the river channel may

be reduced. A stormwater event causing heavy rainfall in a short time period may lead to

increased water elevation level with the channel, eventually causing flooding. The flow

state for both flow profiles has been determined to be subcritical.


21

References

Brunner, G. W. (2010). HEC-RAS, River Analysis System Hydraulic Reference Manual v

4.1.

Ari Abubaker HEC-RAS

T H E U N I V E R S I T Y O F S A L F O R D

S C H O O L O F C O M P U T I N G S C I E N C E A N D


WATER RESOURCES:

Prepared For:

Dr. Prasad Tumula

Module Lecturer

Prepared By:

Ari Aziz Abubaker

@00335888

24.04.2015


i

Table of Contents

1 Executive summery ............................................................................................... 1

2 Introduction and background ............................................................................ 1

3 Aim and objective ................................................................................................ 3

4 Theory ...................................................................................................................... 3

5 Result analysis ........................................................................................................ 8

6 Discussion .............................................................................................................. 18

7 Critical review ...................................................................................................... 19

References .................................................................................................................. 20


ii

List of figure

Figure ‎4-1 representation of terms in energy equation (Brunner, G. W, 2010). .. 4

Figure ‎4-2 water flowing in open channel with slope (lecture notes) ................. 5

Figure ‎5-1 water surface profile with a discharge is 14m3/s .................................. 9

Figure ‎5-2 change in velocity of the channel with a discharge is 14m3/s ........ 10

Figure ‎5-3 the cross section of river station 1200 with discharge 14m3/s ........... 10

Figure ‎5-4 the cross section of river station 900 with discharge 14m3/s ............. 11



Figure ‎5-7 water surface profile with a discharge is 25m3/s ................................ 14

Figure ‎5-8 change in velocity of the channel with a discharge is 25 m3/s ....... 15






iii

List of table

Table ‎5-1 hydraulic depth, wetted perimeter and hydraulic radius with

discharge 14m3/s ......................................................................................................... 8

Table ‎5-2 recorded data by HEC-RAS for the flow profile 1with a discharge (Q)

is 14m3/s ......................................................................................................................... 8


discharge 25 m3/s ...................................................................................................... 13

Table ‎5-4 recorded data by HEC-RAS for the flow profile 1with a discharge is

25 m3/s ......................................................................................................................... 13


1

1 Executive summery

As part of the water resources module students required completing a study

state analysis of river model by using modelling software (HEC-RAS). In this

report the behaviour of river model was examined and investigated under

two different flow profiles.

2 Introduction and background

Hydrologic Engineering Centre-River Analysis System (HEC-RAS) is a modelling

software with the purpose of create and analyse one dimensional steady

flow ,unsteady flow, sediment transportation and analyse water quality such

as temperature. US Army Corps engineers modified this programme. The HEC-

RAS modelling programme designed by Mr. Gary W. Brunner who was a

leader of HEC-RAS developed team. In addition this software replaced a one

dimensional, steady flow water surface profile programme known as a HEC-2

river hydraulic package. In terms of hydraulic engineering and computing

science HEC-RAS has a major progress over HEC-2 (Brunner, G. W, 2010).

The first version (1.0) of this software released in 1995 then following that time

several other version of this modelling program released. The latest version of

this computer programme realised 2010. There were many Hydrologic

Engineering Centre staff participated in developed this programme for

instance Mr Mark R. Jensen programmed user inter face and graphics and

Mr. Steven S. piper programmed the steady flow water surface profile

computational module ,unsteady flow, and sediment transportation

computation. HEC-RAS is capable to carry out hydraulic calculations for

natural and man-made channels and the main capability of this computer

programme is explained blow (Brunner, G. W, 2010):


2

Study flow water surface: The calculation of water surface profile for steady

gradually varied flow performed by this component of HEC-RAS. This

component also has an ability of modelling supercritical, subcritical and

mixed flow regime water surface profiles. In this component several equations

used in calculation process such as Manning’s equation to calculate energy

losses and momentum equation utilised in the circumstances where the

water surface swiftly varied includes hydraulic jumps, hydraulic of bridges and

evaluating profile at stream junctions. During the computational process the

effect of different obstructions such as weirs, bridges, spillways and etc are

taken into consideration. The main characteristics of this component are

analysing multiple plans, computing multiple profiles, analysing multiple

bridges or opening culverts and optimising split flow at stream junctions. In

addition this component HEC-RAS used in flood insurance studies in order

assesses floodway and evaluate changes in water surface as a result channel

improvement, moreover this component capable for managing flood plain

application (Brunner, G. W, 2010).

Unsteady flow simulation: This is another component of HEC-RAS modelling

programme which has an ability to simulate one-dimensional unsteady flow

all the way through the network channels. This component developed mainly

for calculating subcritical regime. This component has an ability to compute

cross-section of all hydraulic structure such as bridges as well as other

hydraulic structure developed for Study flow water surface. Furthermore,

modelling storage area and connecting to hydraulic and stream reaches are

the main features of this component (Brunner, G. W, 2010).

Sediment transport/moveable boundary condition: The calculation of

sediment transport/ movable boundary due to scour and deposition of over

moderate time performed by this component. This calculation of potential

sediment transport is performed by computing grain size fraction, in that way

allowing the imitation of hydraulic sorting and armouring. There are several

various equation used in the computation process. The main application of

this component is assess deposition in reservoir, estimation of maximum


3

potential scour for the period of large flood events, simulate long term

tendency of scour and deposition in an open flow channel as a result of

change in the frequency and period of water discharge and stage (Brunner,

G. W, 2010).

Water quality analysis: Analysing quality of water in the river performed by this

component of HEC-RAS including temperature and transportation of limited

number of water quality components such as dissolved oxygen, dissolved

organic phosphorus and etc (Brunner, G. W, 2010).

3 Aim and objective

The aim of the experiment was to study the performance of an open flow

channel under two different flow profiles through steady-state analysis. This

aim will be achieved by pursuing following objectives:

Learn how to operate the modelling software HEC-RAS with the

purpose of completing the steady-state analysis for the given river

stations.

Perform steady-state analysis for both flow profiles.

Interpret and show the experimental result for the given data in the

form of graphs and tables

Assess the vulnerability of the channel for the potential flooding under

both flow profile conditions

Assess the reliability of the experiment and those factors that question

the reliability and suitability of the experiment

4 Theory

Slope in the ground causes the water to flow downhill through open channel

and pressure in pipes cause the water to flow. The velocity of water in rivers is

dependent on the sharpness of slopes and velocity of water in pipes is

dependants on the degree of pressure. HEC RAS use several equations to

calculate one dimensional water surface profile for gradually varied flow in


4

both natural and man-made channel. The total energy line of a gradually

varied flow is parallel to the water surface as water move to downhill. By

solving of Bernoulli’s energy equation with the standard method water

surface profile can be calculated, energy equation expressed in equation (4-

1) and figure 4-1 show the representation terms in energy equation (Brunner,

G. W, 2010).

Figure ‎4-1 representation of terms in energy equation (Brunner, G. W, 2010).

Z1 + d1+

= Z2 + d2 +

+ he (Equation ‎4-1) (Brunner, G. W, 2010).

Where

V1, V2 is average velocity (m/s) of flow,

Y1, Y2 is depth of water at cross section (m),

Z1, Z2 is the elevation head (m) and

he, energy head loss

When water is flow in the direction of lower elevation which is indicated in

figure 4-1 the total energy line of a gradually varied flow is parallel to the

water surface therefore by modification of Bernoulli's energy equation this

relationship expressed in equation 4-2.


5

H = Z + d +

Equation ‎4-2

Where

H is total energy

V1 is velocity of flow (m/s),

d is the depth of flow (m),

Z is the elevation head (m) and

g is gravitational acceleration

The differentiation of Bernoulli's energy equation allows finding out the

change in depth of flow with length. The differentiation of Bernoulli's energy

equation with respect to length is shown in equation 4-3 and figure 4-2 show

water flowing in open channel with slope.

Figure ‎4-2 water flowing in open channel with slope (Tumula, 2015)

Equation ‎4-3 (Tumula, 2015)

The modification of equation 3 can be obtained through consideration of

relationship between discharge (Q), area (A) and velocity (V), (Q= Av).

Equation 4-4 is indices the modification of equation 3.


6

Equation ‎4-4(Tumula, 2015)

Where,

is the total energy line slope,

=s, is the slope of the channel and

‘T’ is the top width of the channel

Manning’s energy loss coefficients ‘n’ values used by HEC-RAS modelling

programme to calculate the energy loss due to the friction during flow. In

Chezy’s equation manning’s roughness coefficient is used. The derivation of

this equation expressed in Equation 4-5 (Brunner, G. W, 2010).

V = C√RS then C=

Q=


Where

R is the Hydraulic radius.

In view of the fact that the total energy line slope is equivalent to the slope of

the water surface in a steady flow i = s, therefore equation 5 can be modified

as equation 4-6.

i =


By substituting i in equation 4-4 to the equation of 4-6 and using Bresse

functions to integrate the equation 4-4 normal depth at stations can be

calculated then this process will be repeated for the next upstream station.

The integration of equation 4 after substituting i to the equation 5 is shown

below Equation 4-7.


7


HEC-RAS is capable to compute the cross sectional area, wetted parameter,

top width and hydraulic depth of the channel. If the hydraulic depth is higher

than the depth of the channel floods will expected on the channel.

Calculating channel property depends on the shape of the channel. The

river model in this experiment made of trapezoidal Channel therefore

following formula used by HEC-RAS to calculate channel property (Brunner,

G. W, 2010).

Area of cross-section A = Bd + zd2

Wetted Perimeter P = B +2d

Top width T = B + 2zd

Hydraulic Radius R = area of cross section(A)/wetted parameter (P)

Hydraulic Depth D = area of cross section(A) /top width (T)

o = Bd + zd2/B+ 2zd

Froude number is calculated by HEC-RAS to determine the critical conditions

of the channel. Froude number calculated by using equation 4-8

Fr=v/g.d (Equation ‎4-8)

where,

Fr is Froude number

v is velocity

g is gravitational acceleration (9.81)

d is depth of flow

For Critical flow F = 1


8

For Sub Critical flow F < 1

For Super-Critical flow F > 1

5 Result analysis

In this report steady state conditions of flow in open channel flow that having

a single reach and pass through four data collection stations will be

analysed. The cross section of the river stations are known as 100,600,900 and

1200 in their ascending order. There is no inlet or outlet between these four

stations hence flow in the river will be same all the way through those stations.

From two different measurements it was found that, river carries 14m3/s and

25 m3/s of discharge (Q) and for same measurement of discharge elevation

of water surface was 175 m and 178 m respectively.


discharge 14m3/s

Table ‎5-2 recorded data by HEC-RAS for the flow profile 1with a discharge (Q)

is 14m3/s

River

station

Discharge

total (m3/s)

Wetted

Perimeter (P)

m

Hydraulic Depth

(D)

(m)

Hydraulic

Radius (R)

(m)

1200 14 27.28 0.79 0.79

900 14 29.42 0.99 0.98

600 14 38.45 0.81 0.81

100 14 29.70 0.97 0.96


9

The above table shows the recorded data by HEC-RAS for the flow profile 1

which is discharge (Q) is 14m3/s. The obtained data shows the condition of

the flow which is sub-critical hence Froude number over all stations less than

1. The recorded data also show the change of velocity from station 100

(0.49m/s) to station 1200 (0.65m/s). It was observed that velocity depends on

flow area so when flow area increase velocity decrease and vice versa. The

recorded data show that water surface level increase from station 100 to

1200.

Figure ‎5-1 water surface profile with a discharge is 14m3/s

The water surface profile in figure 5-1 clearly shows the increase of water level

by 0.5m. The water level was increased gradually from station 100 to station

1200. The figure also indicates the length of river reach which is 335m long

hence increase in the water level is over the length of river.


10

Figure ‎5-2 change in velocity of the channel with a discharge is 14m3/s

Figure 5-2 indicates the change in velocity of the channel from 0.49m/s to

0.65m/s. The change in velocity is depends on of slope sharpness, flow area

and Manninig’s (n) value. In addition the higher in n value the lower in

velocity.

Figure ‎5-3 the cross section of river station 1200 with discharge 14m3/s

Figure 5-3 shows the cross section of river station 1200. The potential of

flooding with 14m3/s of discharge would not take place. According to the

obtained information through the HEC-RAS hydraulic depth of the channel is

0.79 (table 5-1) and the depth of the river is 6.5m from (180.7m-174.2m). In

order to flood occur in this river water elevation need to increase by 5.71m.


11

Base of that the possibility of flooding to happen very low with such a

discharge.


Figure i5-4 indicates the cross section of river station 900. The vulnerability of

this river station for flooding is similar to station 1200 which is low. The hydraulic

depth of this station is 0.98. In comparison to station 1200, the hydraulic depth

of station 900 is 0.20m deeper. The difference of hydraulic depth may result of

change in elevation between the stations. Since depth of the river is 6.5m

from (180.7m-174.2m) therefore increase of 5.52m of water level required for

flood to occur hence the chance of flooding is very low to happen with such

a discharge.


12


The cross station for river station 600 indicated in figure 5-5 also not

susceptible for flooding. This is due to fact that hydraulic depth within the

channel is 0.81m for that reason increase of 5.52m of water level required in

order to flood occur consequently the probability of flooding is very low to

happen with 14m3/s of discharge .


Figure 5-6 illustrates the cross section of river station 100. The potential of

flooding with 14m3/s of discharge unlikely happen in this station either. In view

of the fact that hydraulic depth of the channel is 0.97 (table and the depth


13

of the river is 6.5m from (180.7m-174.2m) therefore 5.53m water elevation

increase required for flood to occur.


discharge 25 m3/s

Table ‎5-4 recorded data by HEC-RAS for the flow profile 1with a discharge is

25 m3/s

River

station

Discharge

total (m3/s)

Wetted

Perimeter (P)

m

Hydraulic Depth

(D) (m)

Hydraulic

Radius (R) (m)

1200 25 230.15 1.24 1.24

900 25 238.67 1.49 1.48

600 25 236.86 1.70 1.69

100 25 237.91 1.69 1.69


14

The above table shows the recorded data by HEC-RAS for second flow profile

which is discharge (Q) is 25m3/s. The obtained data shows the condition of

the flow which is sub-critical hence Froude number over all stations less than

1. The recorded data also show the increase of velocity from station 100

(0.06m/s) to 1200 (0.09m/s), it was observed that from station 100 to 600

velocity is the same the reason for that might be a slope which same for both

stations 0.000002m/m. In addition flow in the open flow channel depends on

sharpness of the slope, cross sectional area and Manning’s n value.

The recorded data show that water surface level increase from station 100 to

1200 and at same time flow area and top width decrease. Since discharge is

the same over all stations the elevation of water surface increase by

decreasing top width of the channel.

Figure ‎5-7 water surface profile with a discharge is 25m3/s

The water surface profile clearly shows the increase of water level by 0.5m.

The water level was increased gradually from station 100 to station 1200. The

graph also indicates the length of river reach which is 335m long hence

increase in the water level is over the length of river.


15

Figure ‎5-8 change in velocity of the channel with a discharge is 25 m3/s

Figure 5-8 indicates the change in velocity of the channel from 0.06m/s to

0.09m/s. The change in velocity is a function of slope sharpness, cross

sectional area and Manninig’s (n), in addition the higher in n value the lower

in velocity.



16

Figure 5-9 show the cross section of river station 1200. The potential of flooding

to occur with 25m3/s of discharge is high than first flow profile. According to

the obtained information through the HEC-RAS hydraulic depth of the

channel is 1.24 (table 5-3) and the depth of the river is 6.33m from (180.7m-

174.37m). In order to flood occur in this river water elevation need to increase

by 5.09 m. Base of that the possibility of flooding to happen high with such a

discharge.


Figure 5-10 indicates the cross section of river station 900. The vulnerability of

this river station for flooding is higher than first flow profile for the same station.

The hydraulic depth of this station is 1.49. In comparison to station 1200, the

hydraulic depth of station 900 is 0.24m deeper. The difference of hydraulic

depth may result of change in the elevation between the stations or cross

sectional area. Since depth of the river is 6.33m from (180.7m-174.37m)

therefore increase of 4.85m of water level required for flood to occur hence

the chance of flooding is high to happen in the event of intensive rain in short

period of time hence increase the discharge.


17


The cross station for river station 600 indicated in figure 5-11also more

susceptible for flooding compare to the first flow profile. This is due to fact

that hydraulic depth within the channel is 1.69m for that reason increase of

4.64m of water level required in order to flood occur consequently the

probability of flooding is very high to happen with the increase of discharge I

the storm event.


18


Figure 5-12 illustrates the cross section of river station 100. The potential of

flooding to happen with 25m3/s of discharge is also higher in comparison to

the previous flow profile. In view of the fact that hydraulic depth of the

channel is m1.69 (table 5-3) and the depth of the river is 6.5m from (180.7m-

174.37m) therefore 4.64m water elevation increase required for flood to

occur.

6 Discussion

In this exercise steady-state analysis was performed for the river model by

modelling software HEC-RAS to determine the river properties under two

different flow profiles. The discharge in first flow profile was 14m3/s with a

boundary condition of 175m and the discharge for second flow profile was

increased to 25m3/s with an increase of boundary condition to 178m. In

addition, for these particular flows profile boundary condition indicates the

maximum level of water elevation.

After completing steady-state analysis for both flow profiles, it was observed

that the flow profile with the discharge of 14m3/s and boundary condition of

175m is not vulnerable for flooding. According to the obtained result from the

HEC-RAS maximum hydraulic depth was occurred at river station 900 which


19

was 0.98. In view of the fact that depth of the river is 6.5m from (180.7m-

174.2m) for that reason increase of 5.52m of water level necessary for flood to

happen therefore the likelihood of flooding is very low in the company of

such a discharge. Base of that river model was appropriate and successful.

The steady-state analysis for second flow profile indicates the likelihood of

flooding is higher compare to the first flow profile. Since discharge and

boundary condition are increased from 14m3/s to 25m3/s and 175m to178m

respectively. Flood happen when water level rise to above the river boundary

level. In the event of heavy rain, current discharge (25m3/s) will increase in

short period of time hence increase a water level in the river and increase a

likelihood of flood. For that reason river model was inappropriate and less

effective. Since the Froude number in both flow profiles less than one

therefore flows profile is subcritical.

There are several points which must be considered when designing new

channel such as location of the channel, climate zone. If the channel

constructed in the city that lots of houses and buildings around, it may

perhaps crucial to increase the depth of the channel and or increase the

cross sectional area in order to reduce the likelihood of potential flooding.

7 Critical review

In general HEC-RAS is very useful modelling software for analysing the

behaviour of rivers and expecting flood after obtaining sufficient information

regarding river’s geometry and discharge. The modelling software very simple

and easy to be used with lots of feature for instance analysing one

dimensional steady flow ,unsteady flow, sediment transportation and analyse

water quality such as temperature.

Manning (n) value which represents the roughness parameter of the channel

questions the reliability of result. By and large roughness of the river bed is

vary in different zone such as rock and stone in the natural river, for this


20

reason n value cannot represent the roughness parameter equally for the

whole channel. Human errors when inputting cross section data and

interpretation of the result also affects the result of model analysis therefore

extra attention essential during that process.

References

Brunner, G. W. (2010). HEC-RAS river analysis system user’s manual, version

4.1, Hydrologic Engineering Center, Institute For Water Resources. US Army

Corps of Engineers, Davis, Calif.

Hec.usace.army.mil, (2015). HEC-RAS Features. [online] Available at:

http://www.hec.usace.army.mil/software/hec-ras/features.aspx [Accessed

31 Mar. 2015].

Tumula, Prasad. (2015). Open Channel Flow. [online]

Blackboard.salford.ac.uk. Available at:

http://blackboard.salford.ac.uk/webapps/portal/frameset.jsp?tab_tab_grou

p_id=_2_1&url=%2Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype

%3DCourse%26id%3D_51025_1%26url%3D [Accessed 21 Apr. 2015].

1

T H E U N I V E R S I T Y O F S A L F O R D S C H O O L O F C O M P U T I N G , S C I E N C E A N D


FE ANALYSIS WITH SEISMIC ENGINEERING

HEC-RAS Coursework

Prepared for:

Dr. Prasad Tumula

Module Lecturer

Prepared by:

Dilawar Ali

2

Contents

List of Figures ............................................................................................................................ 3

1 Introduction and background ........................................................................................... 4

1.1 Preparing channel reach ............................................................................................ 4

1.2 Cross section setup .................................................................................................... 5

1.3 Results ........................................................................................................................ 6

1.3.1 Flow Profile 1 (14M3/s) ...................................................................................... 6

1.3.2 Flow Profile 1 (25M3/s) .................................................................................... 12

2 Discussion ........................................................................................................................ 18

3 Conclusion ....................................................................................................................... 19

References .............................................................................................................................. 20

3

List of Figures

Figure 1-1: River reach given data ............................................................................................ 5

Figure 1-2: River station 100 cross section data ....................................................................... 6

Figure 1-3: Created river reach with the four given river station values .................................. 6

Figure 1-4: Recorded data flow profile 1 .................................................................................. 7

Figure 1-5: Water elevation for profile 1 .................................................................................. 7

Figure 1-6: Velocity water surface graph profile 1 ................................................................... 8

Figure 1-7: Cross section river station 1200 @ 14M3/s discharge ........................................... 9



Figure 1-10: Cross section river station 100 @ 14M3/s discharge ......................................... 12

Figure 1-11: Recorded data flow profile 2 .............................................................................. 12

Figure 1-12: Water elevation for profile 2 .............................................................................. 13

Figure 1-13: Velocity water surface graph profile 2 ............................................................... 14

Figure 1-14: Cross section river station 1200 @ 25M3/s discharge ....................................... 15




4

1 Introduction and background

HEC-RAS is a computer program capable of modelling the hydraulics of

water flow through natural rivers channels (Brunner, 1995). However the

program is limited to one-dimensional analysis, thus limiting it to be able to

directly model the hydraulic effect of cross section shape changes, which go

beyond one dimension such as bends, and other two- and three-dimensional

aspects of flow (Brunner, 1995). The program was developed by the US

Department of Defence, Army Corps of Engineers in order to manage the

rivers, harbours, and other public works under their jurisdiction; it has found

wide acceptance by many others since its public release in 1995.

The main purpose of this software is to allow users to perform one dimensional

steady flow, unsteady flow and sediment transport calculations (Brunner,

1995).

1.1 Preparing channel reach

In order to set out the channel reach the data presented in Figure 1 below is

used to create the river reach.

5

Figure 1-1: River reach given data

1.2 Cross section setup

The data given in Figure 1 is used to set up the cross sections of the river

station. The cross section data, river reach length and Manning’s coefficient

number is entered in the program for all four river stations. An example of this

method is shown below in Figure 2.

6

Figure 1-2: River station 100 cross section data

Figure 1-3: Created river reach with the four given river station values

1.3 Results

1.3.1 Flow Profile 1 (14��/s)

7

Figure 1-4: Recorded data flow profile 1

The Froude number at each river station is less than 1 thus the average

Froude number being less than one (0.175) making the river flow sub-critical.

Water Surface profile 1

Figure 1-5: Water elevation for profile 1

Inspecting Figure 5 it is evident that the river station 1200 has the highest

water elevation value of 174.2 m while the lowest elevation level is at river

station 100 with a value of 173.7. The difference in elevation between river

station 100 and 1200 being 0.5m.

8

Figure 1-6: Velocity water surface graph profile 1

The graph shows a variation of velocity between river station 100 and 1200

where the velocity decreases at a constant rate, until it reaches 150 m

(channel distance), followed by a velocity increase from the channel

distance of 150 m to 250 m, at constant rate and finally there is a rapid

increase of velocity at the river station 1200. This could be due to the fact that

river station 1200 is located at a higher level than river station 100.

9

Water surface elevation cross section

Figure 1-7: Cross section river station 1200 @ 14��/s discharge

Observing Figure 7 it can be seen that with flow profile 1 of 14M�/s at river

station 1200 i.e. downstream flooding to occur is highly unlikely as water level

is much less than the maximum level of the river cross section. Also further

observation shows that there are no run off for excess water due to the water

level being less than that of the left and right overbanks.

10


From observing Figure 8, we can see that there is little chance of flooding as

the highest surface elevation is 180.5 (m). Also further observation shows that

there are no run off for excess water due to the water level being less than

that of the left and right overbanks.

11


From observing Figure 9, we can see that there is little chance of flooding as

the highest surface elevation is 180.2 (m). Also further observation shows that

there are no run off for excess water due to the water level being less than

that of the left and right overbanks.

12


Observing Figure 10 it can be seen that with a flow profile 1 of 14M�/s at river

station 100 i.e. upstream flooding to occur is highly unlikely as water level is

much less than the maximum level of the river cross section. Also further

observation shows that there are no run off for excess water due to the water

level being less than that of the left and right overbanks.

1.3.2 Flow Profile 1 (25��/s)

Figure 1-11: Recorded data flow profile 2

Similar to flow profile 1 the Froude number at each river station is less than 1

thus the average Froude number being less than one (0.02) making river flow

sub-critical.

13

Water surface profile 2

Figure 1-12: Water elevation for profile 2

Inspecting Figure 12 it is evident that the river station 1200 has the highest

water elevation value of 174.4 m while the lowest elevation level is at river

station 100 with a value of 173.7. The difference in elevation between river

station 100 and 1200 being 0.7m.

14

Figure 1-13: Velocity water surface graph profile 2

Unlike profile 1 there is less variation with the velocity here as the velocity

changes only at one point (150m).

15


The probability of flooding increases as the discharge value increases as the

same river station with a smaller discharge value of 14M�/s (Figure 7) shows

very small rise in water levels. Also further observation shows that the left and

right overbanks have been submerged under water. This is a further indicator

to a rise in potential flooding.

16


Similar to the previous river station flooding is more likely here compared to its

corresponding discharge value of 14M�/s (Figure 8). Also further observation

shows that the left and right overbanks have been submerged under water

just like river station 1200. This is a further indicator to a rise in potential

flooding.

17


Similar to the previous river station flooding is more likely here compared to its

corresponding discharge value of 14M�/s (Figure 9). Also further observation

shows that the left and right overbanks have been submerged under water

just like river station 1200. This is a further indicator to a rise in potential

flooding.

18


Very little seem to have changed from the previous river station as the water

level is the same (178m) on the y-axis thus flooding chances at this river

station are similar to previous river stations under 25M�/s i.e. very little chance

of flooding to occur. However the chance of flooding here is greater than

corresponding discharge value of 14M�/s. Also further observation shows that

the left and right overbanks have been submerged under water just like river

station 1200. This is a further indicator to a rise in potential flooding.

2 Discussion

Based on the cross section figures flooding of the floodplain seems unlikely at

all four river stations under both circumstances of discharge values. It does

however seem apparent that the likely hood of the surface water level to

exceed the floodplain level is directly proportional to the discharge value.

This can be seen when comparing the set of cross section figures for profile 1

i.e. discharge value of 14M�/s with the corresponding set of cross section

figures for profile 2 i.e. 25M�/s. The surface water level increases significantly

when the discharge value is increased although far from any danger of

flooding the floodplains.

19

3 Conclusion

The model created in this report is only 1 dimension therefore, it is limited in

the level of analysis it can accomplish. If the model was conducted in 3D

surely it would allow user to observe the model in much more detail.

20

References

Brunner, G. W. (1995). HEC-RAS River Analysis System. Hydraulic Reference Manual. Version 1.0: DTIC Document.


274

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Appendix A – Health and Safety A detailed risk assessment for on-site activities has been provided on the following pages.


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Comments or Control Measures Specified by the Assessor

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Site Setup

Slip/ Trip/ Fall Site Personnel

L M M Workers should wear PPE including safety shoes. Good lighting provided in all areas and routes should be cleared. Any spillage should be cleaned up instantly.

L M L

Falling objects from above

Site Personnel

M L M Verify suitable PPE should be worn for example, helmets. All objects above should be secured carefully to avoid it from falling

L L L

Water underneath the ground

Workers H H H Flooding can happen. Keeping in mind the end goal to guarantee nobody gets hurt, CAT sweep is untaken to spotted administrations. Additionally specialists ought to have a grant to dig.

H L M

Working nearby water or above

Site Personnel

H M M Dangers include falling into the water. The specialists ought to be prepared when working close to water.

M L M

Working close by to traffic

Site personnel

M M M Give detachment and assurance where conceivable with the goal that plants, labourers and overall population don’t conflict.

L L L

Children trespassing

Public M M M Individuals can trek and slip into sewer vents and so forth. To evade this risk, the site should be appropriately secured with the goal that the overall population have no right to gain entrance to the site. People in general should be educated about the area that is being built and this should happen before the development takes place. There should be clear signs that development is occurring and general society should have a safe course to utilise while the development is still on going.

M L L

Gas underneath the ground

Site Personnel

H H H The risks are, a blast can happen or a spillage. Keeping in mind the end goal to guarantee nobody gets injured, CAT output is untaken to find administrations. Likewise specialists should have a license to dig.

H L M


280

Surveying at the wrong place

Site personnel

L M M The surveyor needs to verify that they experience the configuration arrange completely and guarantee all information is precise to maintain a strategic distance from mix-ups

L L L

Manual handling Workers L H H Gloves given to workers when handling tools. Workers should be trained in manual handling. Lifting hooks and panel trolleys should be accessible for moving boards. All workers ought to be legitimately advised in the right lifting technique.

L M M

Working with height

Workers L M M Stepladder should be in good state. Only workers who are trained should work at height.

L L L

Vehicle Management

Crane falling into excavation

Site personnel

L H M Guarantee the crane incorporates hostile to crash gear and the administrator should be dependable. This guarantees that the individual assigned does this undertaking legitimately and a manager should be on location

L M L

Failure of scaffold Workers L M M Manager to ensure the precise scaffold is provided and reviewed. There should an obligation for the scaffold including the suitable load rating. The scaffold shoud not be overloaded.

L L L

Machinery Workers L M L Workers have adequate space to work securely around machines. All workers should be trained and all machines shoud have safety features such as brakes and managers should observe at times.

L L L

Failure of excavator

Workers L H H Administrator should be prepared. The eqiupment should be inspected at whatever point its being utilised and should be evaluated before any scraping is done

L H M

Impact with street activity and walkers when turning vehicles into site.

Pedestrian and

workers

L H M All worker educated of safe frameworks of work and activity administration framework. all workers and site guests to wear high visibilty vests. allow adequate road width for vehicles to pass on essential road of site. ensure that banksman are utilised when turning around vehicles on or off site. sufficient signage to be set up around the site border to caution people on foot of risks and immediate them to the right

L M M


281

Workers colliding with moving plant

Worker L H H Safe route to work and on the first day for workers to work, they should be instructed on health and safety plan. All safe routes should be cleared and all workers on site should wear high visibilty vests.

L M M

Crash with plant, vehicles, and materials.

Workers L H M Vehicles to be determined forward where practical. All banksmen to be prepared utilising right hand signals and support drivers. All banksmen and workers to wear high vest. Banksman to be noticeable to drivers at all times

L M M

Hand tools

Dangers to eyes and cutting bricks

Workers L H H PPE should be worn including safety goggles when cutting bricks. L M M

Chipping/ Shattering Tools Sharp Blades Edges

Workers L H H General mindfulness preparing needed, alongside particular preparing for abnormal devices. Operatives to be told to clean store and perserve devices. Provision and wearing of fitting PPE. Damaged devices to be given back to the supervisor. All devices to be routinely investigated to guarantee quality. Tools should be used for their proposed objective

L M M

Functioning cement mixer

Workers L M M The mixer should be placed in secure level ground and should be completely guarded. The supervisor should ensure mixer isn’t damaged. Give careful consideration at all times and be mindful of pipes being moved amid the mix concrete process.

L L L

Vibration from equipment being use for example angle grinder

Workers L L L Block spiltter should replace angle grinders to avoid vibration. L L L

Concrete Pumping

Deterioration of concrete shuttering

Site personnel

L H M The arrangement should not be hurried. The builder should give careful consideration to the detailing. To control the danger, PPE must be worn especially goggles and gloves. Work force pouring should be exceptionally cautious taking care of cement spilling and also verifying anybody not included should be cleared from site.

L M L

Collapse of rebar foundation cages

Workers L H M Ensure appropriate and adequate workbench/trestles are provided satisfactorily to take expected burden

L M L


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Injury to person in area of pumping.

Workers L M L All site concrete individual to be advised before concrete pumping and all dangers involved when concrete pumping operations. Only assigned individual to be in the region of the setting hose, and cement pumping

L L L

Over turning of pump. Failure of boom due to inadequate firmness.

Workers L L L The builder should guarantee outriggers are stretched out to the proper position. Guarantee the cement pump is situated up in a position to guarantee satisfactory space is accessible for the full sending of its outrigger.

L L L

Working at height above the pump level

Workers L H M Entrance might be confined to brief times merely. For longer span undertakings, for example, to change a channel seal, the utilisation of a bridle and limitation cords will be needed. No hirer work force might be allowed to get to the pump

L H L

Distending steelwork/ rebar

Workers L H M Cut to floor level where possible. Barrier off regions. Install steel bar mushrooms on top of steel/ rebar.

L H L

Excavation

Overhead lines Site Personnel and plant operators

L L L Communicate with the line operative to divert the line elsewhere or to see if line can be cut off. However if the lines cannot be cut off, the plant should be altered so it doesn’t extend to the live lines.

L L L

Risks of excavation failing due to surface water

Site personnel

L H M There should be no considerable amount of ground water when site investigating. Water pump should be placed on site in case of heavy rain

L M M

Poisonous gas inhalation

Site Personnel

L M L Gas tester should be used to see if air is clear and if toxic gases are available, eliminate it and test the air again

L L L

Plant tumbling into excavation

Site Personnel

M H M There should be a specific routes arranged for plants and stop blocks should be provided. To help plant operators, banksman should assist.

M M M

Site personnel falling into excavation

Site Personnel

L M M Supervisor should observe and around the excavation, barriers need to be place.

L M M


283

Buried services Workers L L L Use CAT to spot and find buried services. To uncover current services, hand-digging procedures should be used. Banksman to analyse places being excavated for undiscovered services.

L L L

Ground polluted linked to present foul manhole

Site Personnel

M M M PPE should be provided to all workers such as gloves, respiratory protection and eye protection. The supervisor should observe.

M L M

Unstable excavation

Worker M H H Unstable excavation can lead to excavation collapsing. Sheet piled excavation to be composed as per all important outline codes/ codes of practice and present best practice for TWs by suitable staff. TWs creator to impart right establishment arrangement/ exercises to guarantee establishment of TWs meets/ accomplishes plan purpose. The use of trestles is used to keep up a high value sheet pile establishment, diminish the danger of prompting destabilising loads and additionally guaranteeing a configuration agreeable establishment.

M M M

Overloading of TWs equipment

Worker M H H Greatest hydrostatic burden limited to plan esteem. Groundwater must be restraining any potential changes to the outline groundwater level that could increaser the hydrostatic replenishing on the temporary works.

L M M

Failure of Equipment when plant is used to pick up loads.

Worker L H M All machine operators to be skilful to CPCS standards. Capable, qualified slinger to sling loads and immediate machine administrators. Ensure sufficient supervisor is on site. Site administrator to guarantee that revise excavator is utilised for the chosen work. Only excavators with legitimate test certificate should be utilised for lifting operations. The weight of the load to be surveyed before the lift operation. Machines to be examined before used.

L M L

The trench may fail during construction

Worker L H M Operatives to be prepared in removal strategies. Ensure sufficient and suitable gear is accessible to backing the excavation and counteract breakdown. Excavations to be investigated before each movement and recorded. If there are any instabilities in regards to the wellbeing of the trench work must be halted instantly and the site manager must be called

L H L


284

Workers may be brutally/ fatally injured by excavators.

Workers L H H Site specialists are to stay vigilant and caution at whatever point mechanical diggers are on location particularly when they are turning around. The excavator must be managed at all times when unearthing and going around the building site. A first aider must be on location at all times on the off chance that there are any wounds to workers

L M M

Deep Excavation Workers L H H Danger of area slip, and specialists can slip and excursion into the opening. To evade this, the sustenance of the removal should be conformed to minimise the profundity of the excavating. Different systems can be utilised when working with stature. Obstructions should be put around the uncovering. Should be adjusted to minimise the profundity of the excavating to stay away from mischances. Safe system when working with height.

L M M

Excavating and piling close to existing structure

Structure M M M Measure to lessen the vibration and expand separation the loads from existing structures

L L L

Miscellaneous

Explosion/ Fire Workers L H H Essential action should be taken and follow risk assessment. Appropriate fire extinguisher should be kept in suitable places.

L M M

Exposure to dust Workers L M L Appropriate respiratory protective equipment, Local exhaust ventilation (LEV)for dusty locations and workers need to be qualified to use it. LEV should be kept in a good state and should work properly.

L L L

Air compressor failure

Workers M M M All connections must be properly clamped. L M L

Results from noise or dust on site

Workers M M M PPE ought to be accommodated the labourers to shield them from damage. A few exercises should occur at sure times to evade surge hours so the overall population are not influenced by the clamour or dust.

M L L