PILING DESIGN CALCULATIONS

PROPOSED 33 STOREY OFFICE TOWER

Plot No. 03251264 @ SEEF AREA,

BAHRAIN

JULY, 2009

List of Contents:

1.0 Location plan 2.0 Soil Report 3.0 Piling Design Calculations

3.1 900mm Bored Pile

4.0 Reinforcement Details 5.0 Load Test Procedure

6.0 Concrete Mix Design

Location Plan

Soil Report

Piling Design Calculations

900mm Bored Pile

Diamater : 900 mm, pile diameter Pile Capacity In CompressionFOS 1 : 3.00 factor of safety for skin friction

FOS 2 : 3.00 factor of safety for base resistance

Depth Ultimate Allowable Ultimate Allowable Wt. of Ultimate Allowablefriction friction end bearing end bearing Pile Capacity Capacity

0 0 0 0 0 0 0 01 0 0 0 0 0 0 0

1.5 0 0 0 0 0 0 02 2 1 126 42 8 128 35

2.5 6 2 207 69 15 212 553 14 5 2,032 677 23 2,046 659

3.5 23 8 1,017 339 31 1,040 3164 34 11 892 297 38 926 271

4.5 48 16 1,052 351 46 1,099 3215 63 21 1,199 400 53 1,262 367

5.5 79 26 905 302 61 984 2676 98 33 1,087 362 69 1,185 326

6.5 124 41 3,904 1,301 76 4,027 1,2667 150 50 2,731 910 84 2,881 876

7.5 179 60 3,027 1,009 92 3,206 9778 211 70 3,330 1,110 99 3,541 1,081

8.5 247 82 5,707 1,902 107 5,954 1,8789 286 95 5,224 1,741 114 5,510 1,722

9.5 333 111 5,726 1,909 122 6,058 1,89710.5 672 224 5,726 1,909 137 6,398 1,99511.5 1,011 337 5,726 1,909 153 6,737 2,09312.5 1,351 450 5,726 1,909 168 7,076 2,19114.5 2,029 676 5,726 1,909 198 7,755 2,38715.5 2,369 790 5,726 1,909 214 8,094 2,48416.5 2,708 903 5,726 1,909 229 8,433 2,58218.5 3,386 1,129 5,726 1,909 259 9,112 2,77819.5 3,726 1,242 5,726 1,909 275 9,451 2,87620.5 4,065 1,355 5,726 1,909 290 9,791 2,97421.5 4,404 1,468 5,726 1,909 305 10,130 3,07122.5 4,744 1,581 5,726 1,909 320 10,469 3,16923.5 5,083 1,694 5,726 1,909 336 10,808 3,267

L pile = m, provided pile length below road level = m, pile length below Cut-off level

P prov. = kN, provided pile capacity

P req. = kN, Required pile capacity

2,876

Since Pprov > Preq ------> OK Pile length is Adequate

18.5

2,800

19.5

Pile Capacity (KN)

0

00128212

2,0461,040

9261,099

1,262984

1,1854,027

2,8813,206

3,5415,954

5,5106,058

6,398

6,737

7,076

7,755

8,094

8,433

9,112

9,451

9,791

10,130

10,469

10,808

0

003555

659316271321367

267326

1,2668769771,081

1,8781,722

1,897

1,995

2,093

2,191

2,387

2,484

2,582

2,778

2,876

2,974

3,071

3,169

3,267

0

5

10

15

20

25

0 10,000 20,000

Pile Total Capacity

Dep

th b

elow

GL

(m)

Ultimate Allowable

Project : Piling WorkSubject : Calculation of Bored pile Based on BH (3) REF pile: 1 Sheet 1 of 2

Input :Diamater : 900 mm, pile diameter fb(max) = 9,000 kPaType : Bored Pile fs(max) = 120 kPaFOS 1 : 3 factor of safety for skin friction WT = 1.0 m, water table below ground levelFOS 2 : 3 factor of safety for base resistance ks: 0.90 coefficient of earth pressurefcu : 40 N/mm2, concrete strength δ/φ : 0.67 ratio of sliding angle/friction anglePreq : 2800 kN, Design Working Load COL = 1.0 m, cut off level below NGLTs = 0 kN, Design tension load SPT (max) = 200 max SPT allowedStc : 6,364 Structural Capacity Sv'(max) = 200 max allowable vertical overburden prusserWt : 189 kN, weight of pile

RL (m) Layer Thick. γ RQD quc SPT Sv' ks x Sv' tan(δ) (Nq-1) α β fs Ps fb Pbblows penetration (kN/m3) (%) (MPa) actual (kPa) (kPa) (kPa) (kN) (kPa) (kN)

(m) (mm)0 0 0 01 1 2 SAND 19 300 17 16 19 0 0 0.34 31 0.13 0.65 0 0 0 0

1.5 0.5 2 SAND 15 300 17 16 15 0 0 0.34 31 0.13 0.65 0 0 0 02 0.5 2 SAND 3 300 17 16 3 4 3 0.40 55 0.13 0.65 1 2 198 126

2.5 0.5 2 SAND 1 300 17 16 1 8 7 0.37 41 0.13 0.65 3 6 325 2073 0.5 2 SAND 39 300 17 16 39 12 11 0.53 264 0.13 0.65 6 14 3,195 2,032

3.5 0.5 1 CLAY 14 300 17 16 14 16 15 0.45 98 0.13 0.65 7 23 1,598 1,0174 0.5 1 CLAY 8 300 17 16 8 21 19 0.42 68 0.13 0.65 8 34 1,402 892

4.5 0.5 1 CLAY 8 300 17 16 8 25 22 0.42 67 0.13 0.65 9 48 1,653 1,0525 0.5 1 CLAY 8 300 17 16 8 29 26 0.42 65 0.13 0.65 11 63 1,885 1,199

5.5 0.5 1 CLAY 2 300 17 16 2 33 30 0.38 43 0.13 0.65 11 79 1,422 9056 0.5 1 CLAY 3 300 17 16 3 38 34 0.39 45 0.13 0.65 13 98 1,709 1,087

6.5 0.5 2 SAND 23 225 17 16 31 42 38 0.49 147 0.13 0.65 18 124 6,136 3,9047 0.5 2 SAND 18 300 17 16 18 46 41 0.45 93 0.13 0.65 19 150 4,293 2,731

7.5 0.5 2 SAND 19 300 17 16 19 50 45 0.45 95 0.13 0.65 20 179 4,758 3,0278 0.5 2 SAND 20 300 17 16 20 55 49 0.45 96 0.13 0.65 22 211 5,234 3,330

8.5 0.5 2 SAND 27 225 17 16 36 59 53 0.49 152 0.13 0.65 26 247 8,971 5,7079 0.5 2 SAND 31 300 17 16 31 63 57 0.48 130 0.13 0.65 27 286 8,211 5,224

9.5 0.5 2 SAND 50 150 17 16 100 67 61 0.55 255 0.13 0.65 33 333 9,000 5,72610.5 1 4 ROCK 17 0 16 71 64 0.34 27 0.13 0.65 120 672 9,000 5,72611.5 1 4 ROCK 20 0 20 81 73 0.34 26 0.11 0.65 120 1,011 9,000 5,72612.5 1 4 ROCK 20 67 20 91 82 0.34 25 0.11 0.77 120 1,351 9,000 5,72614.5 2 4 ROCK 20 43 20 101 91 0.34 24 0.11 0.65 120 2,029 9,000 5,72615.5 1 4 ROCK 20 83 20 121 109 0.34 23 0.11 0.88 120 2,369 9,000 5,72616.5 1 4 ROCK 20 70 20 131 118 0.34 23 0.11 0.79 120 2,708 9,000 5,72618.5 2 4 ROCK 20 82 20 141 127 0.34 22 0.11 0.87 120 3,386 9,000 5,72619.5 1 4 ROCK 20 69 20 161 145 0.34 21 0.11 0.79 120 3,726 9,000 5,72620.5 1 4 ROCK 20 31 20 171 154 0.34 21 0.11 0.65 120 4,065 9,000 5,72621.5 1 4 ROCK 20 97 20 181 163 0.34 21 0.11 0.98 120 4,404 9,000 5,72622.5 1 4 ROCK 20 60 20 191 172 0.34 20 0.11 0.72 120 4,744 9,000 5,72623.5 1 4 ROCK 20 83 20 200 180 0.34 20 0.11 0.88 120 5,083 9,000 5,726

1 = CLAY 2 = SAND 3 = SILT 4 = Rock

For ROCKSPT

For SOILSoil Type

Soil Parameters Rock Parameters

P

Pile Capacity in SoilSkin Friction

As = surface area

End Bearing fs fs

Pile Capacity in RockAb = area of base

Pile-Rock Frictional Resistance fb

Table 1: RQD vs. J

RQD J

Pile-Rock End Bearing Resistance %

0 - 25 0.2

25 - 50 0.2

Where: 50 - 75 0.2 - 0.5

quc : Mpa, average unconfined compression strength along shaft 75 - 90 0.5 - 0.8

quc : Mpa, average unconfined compression strength at base of pile 90 - 100 0.8 - 1.0

RQD : %, Rock mass Designation

fbr = kN/m2, ultimate end bearing in rock = 2.0 x quc(base) (Rowe and Armitage, 1987) *by Hobbs

α = rock socket reduction factor

β = rock socket reduction factor

J = reduction factor for discontinuities in rock mass

Pile Capacity in Tension

Method (1) :

Method (2) : ADOPTED

Wt

Qs = 0.5 x Ks x Svb' x tan (δ) x As

Qb = (Nq – 1) x Sv' x Ab

Ultimate Pile Capacity = Qu = (Qb + Qs)/FOS- Wt

Figure ( 4.38 ) after williams & Pells

0

0.2

0.4

0.6

0.8

1

0.1 1 10 100

Unconfined compression strength (MPa)

rock

soc

ket r

educ

tion

fact

or ( α

)

Figure ( 4.39 ) after williams & Pellis

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Mass factor ( J )

rock

soc

ket c

orre

ctio

n fa

ctor

( β)

Tension Pile Capacity = Qt = (Qsu)/FOS+ Wt

Tension Pile Capacity = Qt = (Qsu) x 0.75 / FOS+ Wt

qucfsr ..βα=

AbfbrPbr .=

1.0 Structural Pile Capacity: Ref. Pile = 2

Dia = 900 mm, pile diameterQall = 2,800 kN, allowable maximum load on top of pileQt = 0 kN, allowable maximum tension load on pile%H = 5% % of horizontal force with respect to the vertical force on top of pileFOS1 = 1.5 factor of safety for horizontal forceFOS2 = 1.5 factor of safety for tension forceL = 19.5 m, pile length below COLFcu = 40 N/mm2Fy = 460 N/mm2cover = 75 mm, steel cover for pile

Proposed Reinforcement:

Main reinforcement = 13 bars of 20 mm, diameter

1.1 Forces in Concrete:

Based on B.S. 8004, the maximum load in Concrete should not exceed0.25 x Fcu x Area of pile

Maximum design load = 0.25 x fcu x 0.25 x(Dia)2 x π x 1000 = 6,359 kN > 2,800 kN <--- OK

1.2 Checking Minimum Reinforcement:

Minimum percentage of compression steel reinforcement according to BS 8110 Part 1 is:

Asc = 0.4% x Acc ….. for 460 N/mm2

Where: Asc = area of steel in compressionAcc = area of concrete in compression

Asc = 0.4% x 0.25 x π x (Dia) 2 = 2,543 mm2

Area of steel provided = 4,082 mm2 > 2,543 mm

<---OK1.3 Checking Pile Compression Capacity:

The maximum eccentricity loading due to deviations during piling construction,should not exceed the value of N (according to B.S 8110, part 1, section 3.8.4.3) given by:

Ac = 635,850 mm2

As = 4,082 mm2

N = 10,174 + 1502.176 = 11,676 kN

Taking factor of safety = 1.5 then,

N = 0.4 Fcu Ac + 0.8 Fy As

= 7,784 kN > 2,800 kN <---OKTherefore the pile section can take the applied load.

1.4 Checking Reinforcement for Tension Force:

Tension force on pile = 0 kN

Ts = 0.95 x Fy x As / FOS2

Where:Ts = Tensile Force in Reinforcement

As = Area of steel provided = 4,082 mm2

Ts = 1,189 kN > 0 kN

``` OK ----> Steel Reinf. Is Adequate1.5 Additional Forces on Pile

According to B.S 8004, section 7.4.2.5.4. considering out of position tolerance of 75 mm and out of plumb tolerance of 1:75, the loads acting on the piles can be calculated as follows:

Maximum vertical load = 2,800 kN

Horizontal load from out ofPlumb condition = HN = Qall x FOS1 = 56 kN

75

Assumed horizontal load = 5% x vertical load on pile

= 140 kN

Total horizontal force = 196 kN

1.6 Spacing between the vertical bars:

Maximum spacing between steel bars should be > 100 mm

Dia of steel cage = 2,356 mm

Spacing between bars = 181 mm

OK spacing between bars > 100 mm

1.7 Determination of Maximum Bending Moment:

The pile behavior shall be assumed as an elastic beam on soil, the maximum bending moment is calculated as below:

Assuming fixed pile head.

Where,Mf = bending moment in the pile.Fm = coefficient of bending moment (figure 6.39b)

Mf= Fm x H x T

T = stiffness factor = (E.I/Nh)1/5

E = 26,000 MPa, for concrete

I = π x d4/64Nh = coefficient of sub grade modulus

= 45 kN/m3, for weathered RockFor Pile Diameter = 900 mm

I = π x d4/64 = 3.22E-02 m4

T = 1.79 m

H max = 196 kN, total horizontal force

Zmax = L/T ( L = pile length)

Zmax = 10.87 ≈ 11.0

Depth TX(m) (m)

0 0 -0.850.5 0.28 -0.671 0.56 -0.41

1.5 0.84 -0.172 1.11 0.01

2.5 1.39 0.143 1.67 0.21

3.5 1.95 0.254 2.23 0.25

4.5 2.51 0.235 2.79 0.20

5.5 3.07 0.166 3.34 0.12

6.5 1.79 3.62 0.097 3.90 0.05

7.5 4.18 0.038 4.46 0.01

8.5 4.74 0.00

Max. Bending Moment = 299 kN.m

Use maximum B.M = 299 kN.m

-61

81

348758788

6956

-299-237-143

Z = X/T Fm Mf =fm x H x T(kN.m)

20

42301910

Using BS 8110 Chart for circular columns with:Fcu = 40 N/mm2Fy = 460 N/mm2h = 900 mm

hs = h – (2xcover) – (2 xDia of shear steel reinf.) = 730 mmhs/h = 0.81

Using the above mentioned chart:

M = 2.99E+08 = 0.41

h3 7.29E+08

N = 4.20E+06 = 5.19

h2 8.10E+05

use 100Asc = 0.60 % Acc

Area of steel needed = 3,815 mm2

Area of steel provided = 4,082 mm2<---Area of steel provided > area required <------ OK

0

5

10

15

20

25

30

35

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

M/h3 (N/mm2)

N/h

2 (N/m

m2 )

0.40

1

2

3

4

5

6

1.8 Check for Stirrups:

Shear reinforcement = 10 mm @ 150 mm c/c

Fyv = characteristic strength of the link reinforcement = 460 N/mm2

100 Asc (provided) = 0.64 % Ac

from table 3.9 of B.S 8110 Part 1,

Design concrete shear stress (vc) = 0.64 N/mm2

The ultimate shear force = 196 kN Ultimate shear stress = 0.31 N/mm2 < 0.64 N/mm2 <---OK

< 5.1 N/mm2, 0.8 x (fcu)^0.5 <---OK

< 5.0 N/mm2 <---OKMinimum shear reinforcement :

Asv/Sv = 0.4 x b0.95 Fyv

where : Asv = cross-section area of stirrupsSv = spacing of stirrups = 150 mmb =breadth of pile = 900 mm

Asv = 124 mm2

vc = 0.64 N/mm2

v = 0.31 N/mm2

For normal section, Asv/Sv can be calculated as below:

Asv/Sv = (v - vc ) x b0.95 Fyv

If, v > 0.5 x vc ----------> use the above equation

If, v < vc ----------> nominal link must be provided

If, v < 0.5 x vc ----------> no need for shear reinforcement

Since : v < 0.5 x vc vc

then : no need for shear reinf., however, use nominal steel

Reinforcement Details

Reinforcement Details:

NGL COL (Cut-off Level = -1m)

13T20

T10@150mm

19.5m

Full Length Longitudinal bars

Spiral bars

900 mm Diameter Bored Pile

Load Test Procedure

Static Load Test Procedure: The piles shall be tested by applying loads for a specific time intervals or until the rate of settlement falls to a specific value. The test will be carried out in accordance with B.S 8004-1986.

a. Load Measurement:

The load will be applied by a hydraulic jacks and the pressure will be recorded with a calibrated pressure gauge. The hydraulic jacks will act against a reaction system. The reaction system consists of concrete blocks arranged carefully on top of the tested pile or a tension piles to be used instead of concrete blocks.

b. Measurement of pile settlement: During loading the pile, the settlements are recorded with dial gauges with accuracy of 1/100.

c. Working load test: Pile Dia

(mm) Working load

(kN) Testing load

(1.5 x working load) (kN)

Type of load

900

2,800

4,200

Compression

d. Performance of the Test according to B.S 8004:

Load (%)

Reading (min.)

25% of working load

50% 75% 100% 50% 0% 50% 100% 125% 150% 100% 50% 0%

0, 5, 15 min 0, 5, 15 min 0, 5, 15 min

6 hrs. 0, 10 min 0, 10 min 0, 10 min 0, 10 min

0, 5, 15 min 6 hrs.

0, 10 min 0, 10 min

1 hr.

Note: The next load step shall be applied only if the rate of settlement has

become less than 0.25 mm per hour.

A

Counter weight Plate

main girderGirder Hydraulic jack support

Dial guage

A

Reference beam

6.0m

Counter weight Plate

main girder support

Dial guage Hydraulic jack

Reference beam

Section (A-A)

6.0m

v

Concrete Mix Design