ifrc sru sd tue engineering humanitarian steel

Engineering humanitarian steel (vs. best practice)

Roel Gijsbers

TU/e Shelter Research GroupTU/e Shelter Research Group

Introduction

After the symposium Innovative Shelter 21-23 Nov 2007, the Shelter Research Group (SRG) was formed as a part of TU/e, faculty of the Built Environment.The objective is to actively support the humanitarian aid movement with innovative solutions for post disaster sheltering

DEMAND

for post-disaster sheltering.

SUPPLY

Private sector

The SRG consists of members with different backgrounds and interests which include product development, building technology, building physics, structural engineering, impact

/Shelter Research Group 9-11-2011

measurement and includes also a staff member of the Netherlands Red Cross. All members are academia and have a wide network within the industry.

Contents

I. Engineering methods (roughly to detailed)1. Intuition2. Rules of thumb3. Basic Calculation4. Detailed calculation

II. Vital structural aspects1. Material quality2. Stability3. Connection stiffness4. Foundation5. Risk estimation and hazard resistance

III. Engineering examplesg g p1. Pakistan: transitional steel frame shelter

+ Parametric core shelter design + Mapping of wind & snow loading

2. Haiti: 2 storey family shelter


y y3. Collective Centre

Engineering methods

1. Intuitiona) Traditionb) Professional experience


Engineering methods

2. Rules of thumb

Structural element Section and top view Profile size Span Ratio

dSingle layer

d [mm] l [m] d

l

Wide profile or tube steel

100-500

6-14

20-30p

Profile steel

200-1000

6-40

18-26


Engineering methods

3. Basic calculations− By ‘hand’− Basic modeling


Engineering methods

3. Detailed calculations− (3D) Computer modeling− Detailed insight in performance of structural parts


Vital engineering aspects

1. Material quality2. Stability3. Connection stiffness4. Foundation5 Risk estimation and hazard resistance5. Risk estimation and hazard resistance



1. Material quality● Structural steel

St d di d lit- Standardized quality- Hot rolled / cold formed- Tensile strength / Yield strength- s235 / s275 / s355 (and higher)s235 / s275 / s355 (and higher)- Available profiles



2. Stability● Excessive deformation leads to unsafe situations

Stiff l b i / i id ti● Stiff planes: bracing / rigid connections● Stability in every plane: x/y/z● 2nd order effects: loads on already deformed structure

Rigid connections


Bracing


3. Connection Stiffness● Rotational capacity

F (hi )- Free (hinge)- Flexible - Rigid

● Strength of joint itselfStrength of joint itself- Material quality- Production quality



4. FoundationAll forces are transferred to the foundation!

S il h t i ti● Soil characteristics− Soil type− Groundwater table− Vegetation Type and size of foundationVegetation− Site history

● Direction and magnitude of forces● Available materials

yp



1. adequate depth and mass of foundations to resist uplift

Foundations resisting uplift forces: Deep and/or heavy footings

windto resist uplift

2. pile foundations in soft ground with adequate shear friction resistance to prevent pile being pulled out of the groundpile being pulled out of the ground


5. Risk estimation and hazard resistance ● Basic assumptions for structural safety calculations● Shelter Lifespan (1, 5, 10, 25, 50 years?)● Return period of hazards● Magnitude of loadings● Financial constraints

Wh t l l f i k i t bl ?What level of risk is acceptable?

Which standards are applicable?Which standards are applicable?



Risk: Coping with Nature

Disaster magnitude versus

Ri k f dRisk of exceedence

Natural hazards• Geophysical• Meteorological• Hydrological• Climatological


WORLD MAP OF NATURAL HAZARDS

/ Faculty of the Built Environment PAGE 159-11-2011


Natural catastrophes worldwide 1980-2009

Source: Munich Re, 2010 Ri k i i i !Source: Munich Re, 2010 Risk is increasing!/Shelter Research Group 9-11-2011

Engineering issues for shelters

• Lack of appropriate structural norms and calculation methods for humanitarian sheltering• Local or continental building codes are based on regular and permanent buildings • Current standards for sheltering provide no clear information

• Undefined risk profileU d fi d k l l f h d d t l d t b t d• Undefined or unknown level of hazardous and extreme loads to be expected

• Underestimation of applied loadings leading to unsafe solutions (intuition)• Overestimation of applied loadings leading to economic disadvantage• Overestimation of applied loadings, leading to economic disadvantage

• Unknown material quality of locally available steel• Unknown production quality of locally produced componentsUnknown production quality of locally produced components• Unknown construction quality of a locally assembled (self help) shelter

• Lack of structural expertise in the field to judge safety and reliability of


p j g y ysolutions within a specific context

EXAMPLES

• Pakistan: Transitional Steel Frame ShelterParametric steel core shelter frameParametric steel core shelter frame

• Haiti: 2 storey family sheltery y

• Collective Center


Pakistan: transitional steel frame shelter

Parallel Prototyping

Winterized family shelterDesign specifications:• Dimensions: 6 x 4 x 3 m • Structural calculations with boundary conditions: Wi d d 31 / (112 k /h) Wind speed = 31 m/s (112 km/h) Snow load = 300 mm (loose snow)

• Self assembly

First Pakistan prototype



Structural Characteristics Pakistan• Bracing only in walls• Welding of parts to create roof trussesWelding of parts to create roof trusses• Bolting of elements



• Braced in all planes (cables and turnbuckles) • Unknown quality of local welding (wintertime temperature fluctuation cracks)

Structural Characteristics TU/e

Unknown quality of local welding (wintertime temperature fluctuation cracks)• Connection by bolts and nuts

• Modular interchangeable elements



Parallel Prototyping

Pakistan• Experience based design

TU/e• Evidence based designp g

• Member size 18x18x0.9 mm• Total weight 80kg• Calculations missing!!!

g• Member size 40x40x3 mm• Total weight: 400 kg• No roof overhangg

• Upgraded tent•

g• Storm proof dwelling



TU/e Conclusions

• Pakistan prototype seems to be too light dimensioned• Concept of plates, bolts and nuts works• Local production of parts (if material quality is guaranteed)• Flat package in transportation• Concept is easy to setup

Optimization needed because of the heavy weight and worldwide applicability• Loading classes based on local situation • Column height 2000mm1800mm• Shelter size 6x4m 4x4m

Parametric core shelter design



Development characteristics

• Core shelter: 25y lifespan• Core shelter: 25y lifespan

• Weight optimization

• Modular system: self assembly

Worldwide application• Worldwide application

• System variants for loading zones• Wind loading• Wind loading• Snow loading



Snow loading zones

• Not a hazardous load but a largely predictable load• Not a hazardous load, but a largely predictable load

Transitional Shelter standards: 30 kg/m2 (±15 cm of snow)The Netherlands: 70 kg/m2 (x 0.8 = 56 kg/m2)e et e a ds 0 g/ ( 0 8 56 g/ )

• Based on values in Eurocode & academic research• Applicable up to 1500m above sea level

Snow zone

Snow load (kN/m2)

• Applicable up to 1500m above sea level

( / )S0 0 S1 0 ‐ 0,5 S2 0.5 ‐ 1.0S3 1 0 1 5S3 1.0 ‐ 1.5



Wind loading zones

• Basic wind speed• Basic wind speed• Averaging time (3s, 1 min, 10 min, 1 hour)

Average wind speed is less when averaging time increases

• Dominant wind typeAveraging times are dependent on storm types

(t i l l ti t th d t l )(tropical cyclone, synoptic storms, thunderstorms, gales) Most regions experience different wind types, however the most extreme one

is normative



1. Regional/national conditions for basic wind speed Shelter standard in case of Hurricane prone area: 45 m/s (averaging time undefined)

Shelter standard: min.18 m/s(averaging time undefined)

Existing Wind speed classifications

1‐9 10‐11 12Beaufort

LOW

1

MEDIUM

2

HIGH

3

IFRC / Arup International

West African Buidling Code

I II III IV VHolmes

1

A

2

B

3

C

4

D

5Saffir Simpson

Australian Standards / Holmes

/ Architecture, Building and Planning PAGE 279-11-2011

0 10 20 30 40 50 60 70

hourly wind speed (m/s)


Wind speed classification based on storm types

Very useful when no exact local wind speeds are available or known

10 min

Very useful when no exact local wind speeds are available or knownPrevailing wind types normally are!

Wind zone

10‐min mean (m/s)

Storm types 1h mean(m/s)

3‐second gust (m/s)

W1 0‐20 0 ‐ 19W2 20‐31 Synoptic storms / Thunderstorms (3s) 19 ‐ 29.5 30‐45W3 31‐35 Weakening tropical cyclones 29.5 ‐ 33.5W4 35‐45 (Moderately) severe tropical cyclones 33.5 ‐ 43W5 45‐55 Severe tropical cyclones 43 ‐ 52.5



Calculation of extreme wind pressure on shelter (local conditions)• Terrain roughness• Building heightBuilding height• Turbulence intensity• Orographic effects• Aerodynamic effects due to shelter dimensions and form

Windspeed → Wind pressure



3. Calculation for structural safety

f i d ( di t d lif f th b ildi )• reference period (predicted lifespan of the building)• risk of exceedence (yearly extremes statistically independent)• Partial safety factor

The partial safety factor in the structural calculation is used to factor up the return period of the extremes

P ti l f t f tPartial safety factor (1.6 in Eurocode - 50y reference) Windward Antilles: 2.22 (1.492) - Hurricanesthe Netherlands: 1.35 (1.162) - Synoptic storms

Underestimation / overestimation of risk:• A shorter return period substantially decreases the loads applied• It is not legitimate to introduce a standard safety factor for worldwide application

9-11-2011

• Different risk profile for different types of loadings (wind / earthquake / floods)

/Shelter Research Group


Modularity of components



System approach • Weight optimization based on combination of loading zones• 3 system variants fully calculated using 3d modelling• 3 system variants fully calculated using 3d modelling

330 kg (=100%) Wind zones Snow zone W1 W2 W3 W4 W5

snow load 10‐min mean (m/s)

(kN/m2) 0‐20 20‐31 31‐35 35‐45 45‐55

S0 0 276 (83%)

S1 0 ‐ 0,5 203 (62%)

S2 0,5 ‐ 1,0

S3 1,0 ‐ 1,5 231 (70%)

S1-W2a e.g.: non mountainous areas in southern EuropeS3-W2a e.g.: mountainous areas in PakistanS0-W4 e.g.: coastal regions in hurricane prone areas, e.g Australian coast line,


S0 W4 e.g.: coastal regions in hurricane prone areas, e.g Australian coast line, Philippines, Chinese coast line, Leeward islands, Southern Florida, Louisiana

Haiti 2 storey family shelter

Goal: design a 2 storey house structureAvailable information beforehand

• global dimensions• Location (country)• Self help solution

Design and calculations− Several variants and existing solutions were studied


g− Focus on connection details and foundation solution


Detail 1Detail 1

Detail 2 Detail 3



Proposed suggestions from Haiti at the time of the final calculations in NL• Addition of door openings during calculations (in stability planes)• Alteration of global dimensions based on standard wooden sheetAlteration of global dimensions based on standard wooden sheet

dimensions− Less effort on crafting of sheeting does not necessarily mean lower costs,

because it can have structural implications!

Conclusions from this project• Clear brief saves time, effort and costs• Some existing structures might not be fully reliable (stability / resistance

to uplift forces)• Unclear which standards to use for calculation• Foundation:

− No soil information available or delivered− 1 m3 concrete per corner post, a total of 4 m3

Sol tion hea anchoring (speciali ed compan )


− Solution: heavy anchoring (specialized company)

Collective Centre

1. Transport (30ft container)2. Assembly of base module2. Assembly of base module3. Beacon for arriving refugees4. First aid facilities5. Extension6. Centralized community shelter7. Long-term facilitiesg8. Disassembly / re-usable

9-11-2011/Shelter Research Group

Collective Centre

Demands and result: • Quickly available and deployable• Reliable & proven technical solutionsReliable & proven technical solutions • Uncomplicated assembly• No necessity for trained crew, only locals• Flexibilityy• Climate control


Collective Centre

Assembly and deployment


Collective Centre

Aluminium guidance rail

fabric

welded string


Collective Centre

Assembly of membrane

pull


Collective Centre

Transport

30 ft container


Full Scale Testing of 1 segment


Full Scale Testing of 1 segment

PAGE 439-11-2011/Shelter Research Group 9-11-2011

Further goals for the sector

What is still needed in shelter engineering?

• Globally applicable building standards for sheltering and temporary structures

• Insight and agreement on acceptability of risk in relation to financial feasibility

• Mapping of hazards and loading extremes


Thanks for your attention

TU/e Shelter Research Grouphttp://www.innovativeshelter.com

ifrc sru sd tue engineering humanitarian steel

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