(2) Pile Cap Design_columns

Project Job ref

Part of structure Calc sheet no rev

/ 0

Drawing ref. Calc by Date Check by Date

Apr-23 Nov-09

Ref Calculations Output

Design of pile cap - PC4

Line of critical shear

Dia. Of pile = 450 mm B

Offest from pile = 150 mm

Column width = 600 mm

Pile spacing (2L) = 1350 mm

Depth of pile cap = 750 mm

Width of pile cap (B) = 750 mm 2L

Bottom cover = 75 mm

Side cover = 50 mm

Ultimate axial load (N) = 1800 kN

Materials

= 35

= 500

= 1.25 (partial saftey factor for concrete - shear)

= 1.15 (partial saftey factor for steel)

Design for main reinforcement:

Effective depth of pile cap (d) = 653 mm

According to Truss theory:

Tension to be resisted by main reinforcement, T = (N x L) / (2 x d)

= 1800 x 675 / (2 x 653)

= 930.3 kN

According to Flexural theory:

Moment parallel to X axis = 607.5 kNm

K = = 0.054

Z = d(0.5 + √(0.25 - K / 0.9)) = 611.14 mm

Therefore Tx = 994.0 kN

Area of steel required = T / (0.87 x fy)

= 994040 / (0.87 x 500)

= 2286

Dia. Of bars using for main reinforcement = 20 mm

No. of bars required = 7.277

Provide No. of bars = 9 Nos

Area of steel provided = 2827 OK

BS 8110 Spacing of main bars = 78.25 mm

Table 3.25 Percentage of steel = 0.503 % > 0.13 % OK

Φ/5

fcu N/mm2

fy N/mm2

Gm

Gm

M / fcu b d2

mm2

mm2

Project Job ref

Newport Station Regeneration 5074908


Car Park - Design of Pile Caps for Columns 9 / 9 / 0


SJ Jun 08 CMN Jun-08


Check for shear:

Shear stress along critical section (v) = (N / 2) / (B x d)

= (1800 / 2) / (750 x 653)

3.4.5.2 = 1.838 < 5 OK

BS 8110

Table 3.8 100 As / bv d = 0.577 %

Design strength of concrete for shear resistance = 35

= 0.885

= 0.52

Critical section from face of the column (av) = (675 - 300 - 0.3 x 450)

= 240 mm

3.4.5.8 Enhanced shear stress = 2.834 > 1.838 OK

Hence, shear links are not required. However provide nominal T12 links @ 200 c/c.

Side face reinforcement:

3.12.5.4 Dia. Of bar used for side face reinforcement = 16 mm

Spacing of bar =

= 256 mm

Hence, provide side face reinforcement - 2 nos. T16 bars

N/mm2 N/mm2

N/mm2

(400 / d) (1/4)

Design shear resistance ( vc) N/mm2

N/mm2

( ϕ2 x fy ) / b

Project Job ref


/ 0


BVR Apr-23 Nov-09


Design of pile cap - PC2 (For 750x300 column) Y

Dia. Of pile ( Φ ) = 450 mm


Column width in X-direction = 600 mm

Column width in Y-direction = 600 mm

Effective length of pile cap (2 Lx) = 1350 mm 2100 2Ly 750

Effective length of pile cap (2 Ly) = 1350 mm Φ



Side cover = 50 mm

Ultimate axial load (N) = 3500 kN 2Lx X

Reaction of each pile (N/3) = 1167 kN

2100

Materials

= 35 = 1.25 (partial saftey factor for concrete - shear)

= 500 = 1.15 (partial saftey factor for steel)

Design for main reinforcement:Effective depth of pile cap (d) = 637.5 mm


Effective length of pile cap (2 Lxy) = 1509.4 mm

Tension to be resisted by main reinforcement, Txy = (2N x Lxy) / (9 x d)

= 2 x 3500 x 754.675 / (9 x 637.5)

= 920.74 kN

Tension to be resisted by main reinforcement, Ty = (2N x Ly) / (9 x d)

= 2 x 3500 x 675 / (9 x 637.5)

= 823.53 kN

Net tension to be resisted by main reinforcement, Tx = 2 x Txy cos 26.57

= 2 x 920.74 x cos 26.57

= 1647.1 kN

Net tension to be resisted by main reinforcement, Ty = 2 x Txy sin 26.57 + 823.53

= 1647.1 kN


Moment parallel to X axis = 700 kNm

K = = 0.023

Z = d(0.5 + √(0.25 - K / 0.9)) = 605.63 mm

Moment parallel to Y axis = 437.5 kNm

K = = 0.015

Z = d(0.5 + √(0.25 - K / 0.9)) = 605.63 mm


Therefore Ty = 722.39 kN

In X-direction

Area of steel required in X-direction = Tx / (0.87 x fy)

= 1647100 / (0.87 x 500)

= 3786.4




Area of steel provided = 6872.2 OK Provide

BS 8110-1 Spacing of main bars = 153.8 mm 14 Nos. T25 bars


av

Φ/5

av

fcu N/mm2 Gm

fy N/mm2 Gm

M / fcu b d2

M / fcu b d2

mm2

mm2

Project Job ref







In Y-direction

Area of steel required in Y-direction = Ty / (0.87 x fy)

= 1647100 / (0.87 x 500)

= 3786.4




Area of steel provided = 6872.2 OK Provide

Spacing of main bars = 150 mm 14 Nos. T25 bars

Percentage of steel = 0.44 % > 0.13 % OK

Check for shear:

Shear stress along critical section (v) = (2 N/3) / (B x d)

= 2 (3500000 / 3) / (2100 x 637.5)

3.4.5.2 = 1.74 < 5 OKBS 8110

Table 3.8 100 As / bv d = 0.52 %


= 0.89

= 0.51

= (2/3)x1350 - 600/2 - 0.3x450

= 465 mm

3.4.5.8 Enhanced shear stress = 1.4 < 1.74 0

Hence, shear links are required

Check for punching shear:

At column face:

Punching stress = N / (u d)

Perimeter of column (u) = 2400 mm

Punching stress = 2.29 < 5 OK

At Φ/5 from pile face:


Critical perimeter (u) = 3558.7 mm

Punching stress = 1.54

Enhanced shear stress = 1.39 0

Hence, shear links are required



Spacing of bar =

= 256 mm


mm2

mm2

N/mm2 N/mm2

N/mm2

(400 / d) (1/4)


Critical section from face of the column (av)

N/mm2

N/mm2 N/mm2

N/mm2

N/mm2

( ϕ2 x fy ) / b

Project Job ref


/ 0


Apr-23 Nov-09


Design of pile cap - PC1 Y

Dia. Of pile ( Φ ) = 450 mm


Column width in X-direction = 600 mm

Column width in Y-direction = 600 mm

Pile spacing in X-direction (2 Lx) = 1350 mm 2100 2Ly

Pile spacing in Y-direction (2 Ly) = 1350 mm



Side cover = 50 mm

Ultimate axial load (N) = 4300 kN 2Lx X

K' = 0.156

2100

Materials

= 32

= 500

= 1.25 (partial saftey factor for concrete - shear)

= 1.15 (partial saftey factor for steel)

Design for main reinforcement:

Effective depth of pile cap (d) = 662.5 mm


Reynolds Tension to be resisted by main reinforcement, Ty = (2 N Ly)/(4 d)

Hand book = 2 x 4300 x 675 / (4 x 662.5)

= 2191 kN

Tension to be resisted by main reinforcement, Tx = (2 N Lx)/(4 d)

= 2 x 4300 x 675 / (4 x 637.5)

= 2276 kN


Moment parallel to Y axis = 806.25 kNm

K = = 0.027

Z = d(0.5 + √(0.25 - K / 0.9)) = 629.375 mm

Moment parallel to X axis = 806.25 kNm

K = = 0.03

Z = d(0.5 + √(0.25 - K / 0.9)) = 605.625 mm

Therefore Ty = 1281 kN


In Y-direction

Area of steel required in Y-direction = Ty / (0.87 x fy)

= 2190570 / (0.87 x 500)

= 5036

Dia. of bars for main reinforcement = 25 mm



Area of steel provided = 5890 OK Provide



av2

av1

fcu N/mm2

fy N/mm2

Gm

Gm

M / fcu b d2

M / fcu b d2

mm2

mm2

Project Job ref







In X-direction

Area of steel required in X-direction = Tx / (0.87 x fy)

= 2276470 / (0.87 x 500)

= 5233

Dia. of bars for main reinforcement = 25 mm



Area of steel provided = 6872 OK Provide



Check for shear in Y-direction:

Shear stress along critical section (v) = (N / 2) / (Bx x d)

= (4300000 / 2) / (2100 x 662.5)

= 1.55 < 5 OK

Table 3.8 100 As / bv d = 0.42 %


= 0.88

= 0.45

= 1350/2 - 600/2 - 0.3*450

= 240 mm

3.11.4.4.a = 2.5 > 1.55 OK

Hence, shear links are not required.

Check for shear in X-direction:

Shear stress along critical section (v) = (N / 2) / (By x d)

= (4300000 / 2) / (2100 x 637.5)

3.4.5.2 = 1.61 < 5 OK

BS 8110

Table 3.8 100 As / bv d = 0.52 %


= 1

= 0.55

3.11.4.4.a = 1350/2 - 600/2 - 0.3*450

= 240 mm

3.4.5.8 = 2.93 > 1.61 OK

Hence, shear links are not required.

Check for punching shear:

At column face:


Perimeter of column (u) = 2400 mm

Punching stress = 2.76 < 5 OK



Spacing of bar =

= 256 mm


mm2

mm2

N/mm2 N/mm2

N/mm2

(400 / d) (1/4)



Enhanced shear stress = 2 d vc / av N/mm2

N/mm2 N/mm2

N/mm2

(400 / d) (1/4)



Enhanced shear stress = 2 d vc / av N/mm2

N/mm2 N/mm2

( ϕ2 x fy ) / 500

Documents

(2) Pile Cap Design_columns