PILECAP DESIGN CALCULATIONS
Project Name : s
Client Name : s
Engineer Name : s
Design File : C:\Users\Sudeep.PM\OneDrive - Bentley Systems, Inc\Desktop\RCDC -SampleFiles\Staad-Samples\STAAD Sample file new\ACI 318M-14 For PC2.rcdx
Analysis File : C:\Users\Sudeep.PM\OneDrive - Bentley Systems, Inc\Desktop\RCDC -SampleFiles\Staad-Samples\STAAD Sample file new\RCC Wall - RCDC STAAD Demo.std
Analysis Last Modified : 22-Apr-21 12:57:14 PM
Definitions:
1. α = Coefficient of Thermal Expansion
2. ρact = Percentage steel provided
3. A1 = Area of Base for Load Transfer in 'sqm'
4. A2 = Area of Bearing under column in 'sqm'
5. AsfrPrv = Area of face reinforcement provided in 'sqmm'
6. AsfrReq = Area of face reinforcement required in 'sqmm'
7. AstPrv = Area of tensile reinforcement provided in 'sqmm/m'
8. AstReq = Area of tensile reinforcement required in 'sqmm/m'
9. AsvPrv = Area of shear reinforcement provided in 'sqmm/m'
10. AsvReq = Area of shear reinforcement required in 'sqmm/m'
11. Av = Location of section of shear-check from Pile Center
12. Beff = Effective Width for design for bending and shear in 'mm'
13. Beffsfr = Effective Width for design for Face Reinforcement in 'mm'
14. BMux = Factored Design Bending Moment for pile-cap along column D in 'kNm'
15. BMuy = Factored Design Bending Moment for pile-cap along column B in 'kNm'
16. Cx = Width of column in 'mm'
17. Cy = Length of column in 'mm'
18. D = Depth of Pilecap in 'mm'
19. Deff = Effective Depth of Pilecap in 'mm'
20. DfCol = Distance of Pile center to face of column in 'm'
21. Icr = Moment of Inertia of concrete crack section in 'mm4'
22. Mcr = Cracking Moment
23. Mx = Bending Moment in column along Column D (from analysis) in 'kNm'
24. My = Bending Moment in column along Column B (from analysis) in 'kNm'
25. P = Axial load in pile due to Ptotal in 'kN'
26. Pcomb = Axial load in column for a load combination in 'kN'
27. Ppile = Axial Load on pile in 'kN'
28. Ptotal = Total vertical load on pile-cap for a load combination in 'kN'
29. Pmx = Axial load on pile due to moment Mx in 'kN'
30. Pmy = Axial load on pile due to moment My in 'kN'
31. sp = Spacing Between bars at outer most layer in 'mm'
32. Temp1 = Peak Hydration temperature in Degree
33. Temp2 = Seasonal Temperature Variations in Degree
34. Vc = Nominal shear strength provided by concrete in 'kN'
35. Vs Capacity = Shear strength capacity of provided shear reinforcement 'kN'
36. Vu = Design shear force in 'kN'
37. Vus = Design shear force for stirrups in 'kN'
38. Vs = Nominal shear strength provided by shear reinforcement, in 'kN'
39. Vx = Shear in Column along major axis (from analysis) in 'kN'
40. Vy = Shear in Column along minor axis (from analysis) in 'kN'
41. y = Neutral axis depth in 'mm'
42. φ = Strength reduction factor in shear
43. φ1 = Strength reduction factor in concrete bearing
44. Φ1Pnb = Bearing strength of column in 'kN'
 
Code References:
ACI 318M - 14
1. Ptmax : 7.3.3.1, 8.3.3.1, 9.3.3.1
2. Ptmin : 7.6.1.1 & 8.6.1.1/7.7.2.3
3. Vc : 22.6.5
4. Vcper : 22.5.5, 22.5.6
5. AvReq : 22.5.10.5 & 22.6.7
6. Min Shear Reinf : 7.6.3, 9.6.3 & 10.6.2
7. Max Stirrup Spacing : 9.7.6 & 10.7.6
8. One Way Shear Criteria : 13.2 & 13.4
9. Load transfer : 22.8
10. fs,perm : 24.3.2.1
11. fc,perm : 22.2.2.4.1
12. Wcr : Eq 4.2(a)
 
BS 8007 (For Early / Initial Thermal Cracking)
1. Surface Zone for suspended slab : Figure A.1
2. Surface Zone for ground slab : Figure A.2
3. Factors for the calculation of minimum reinforcement : Table A.1



 
Design Code : ACI 318M - 14  
Pilecap No : PC2  
Column No : C2 (700 mm X 700 mm)
Member Ref. No : 101  
       
Concrete Grade : C20  
Steel Grade : Fy420  
Clear Cover : 50 mm
Top of pile-cap below ground : 2.9 m
       
Density of Soil = 18 kN/cum
Founding Depth = 4 m
Pile Capacity in Compression = 1500 kN
Pile Capacity in Tension = 500 kN
Pile Capacity in Shear = 200 kN
Pile Capacity Reduction = 0 %
Pile Overloading = 10 %
Pile Group Overloading = 10 %
Pile Capacity Increase for EQ = 0 %
Pile Capacity Increase for Wind = 0 %
Live Load Reduction = 0 %
       
Consider Capacity Design : Yes  
Consider Overburden Pressure : Yes  
       
No. of Piles = 2  
Pile Diameter = 600 mm
Pile Spacing = 2.5 x Ø
Pilecap Size = 2400 X 900 mm
Pilecap Depth = 1100 mm
Pilecap Offset = 150 mm
Soil Wt. + Pile-cap Wt. = 146.57 kN
       
For design, moments along shorter direction of pile cap has been ignored
       
 
Check for Maximum Load on One Pile:
Critical Load Combination : [9] : (LOAD 1: LOAD CASE 1) +0.75 (LOAD 2: LOAD CASE 2) -0.525 (LOAD 4: LOAD CASE 4 EQ-Y)
Pcomb = 1662.03 kN
Ptotal = Pcomb + (1 x Soil Wt.) + (1 x Pilecap Wt.)
  = 1808.6 kN
Mx = 1.68 kNm
My = -92.87 kNm
P = Ptotal/ No. of Piles
  = 904.3 kN
Pmx = 1.12 kN
Pmy = 0 kN
       
Maximum load on pile = 905.42 kN
Allowable load on pile = 1500 x 1.1
  = 1650 kN
 
Check for Maximum Load on Pile Group:
Critical Load Combination : [2] : (LOAD 1: LOAD CASE 1) +(LOAD 2: LOAD CASE 2)
Pcomb = 1619.21 kN
Ptotal = Pcomb + (1 x Soil Wt.) + (1 x Pilecap Wt.)
  = 1765.78 kN
Mx = -1.37 kNm
My = -13.62 kNm
       
Maximum load on pile group = 1765.78 kN
Allowable load on pile group = 2 x 1500 x 1.1
  = 3300 kN
 
Check for Maximum shear on Pile Group:
Critical Load Combination : [13] : 0.6 (LOAD 1: LOAD CASE 1) -0.7 (LOAD 4: LOAD CASE 4 EQ-Y)
Pcomb = 969.73 kN
Ptotal = Pcomb + (0.6 x Soil Wt.) + (0.6 x Pilecap Wt.)
  = 1116.3 kN
Mx = 3.54 kNm
My = -113.14 kNm
Vx = 45.17 kN
Vy = 1.28 kN
Maximum shear on pile group = sqrt(45.172 + 1.282)
= 45.19 kN
Shear capacity of pile group = 2 x 200 x 1 x 1
  = 400 kN
 
Check for Uplift Load on Pile:
No uplift in any pile
 
Design for Bending:
Bottom Reinforcement Along Column-D
Ppile = Capacity of pile
  = 1500 x 1.5
  = 2250 kN
       
Deff = 1040 mm
Beff = 900 mm
DfCol = 0.4 m
BMux = Ppile X DfCol
  = 900 kNm
PtReq = 0.25 %
AstReq (BM) = 2625.64 sqmm/m
AstPrv = #19 @ 105 C/C
  = 2728.76 sqmm/m
 
Top Reinforcement Along Column-D
D = 1100 mm
AstReq = 1980 sqmm/m
AstPrv = #16 @ 100 C/C
  = 1985.6 sqmm/m
 
Bottom Reinforcement Along Column-B
AstReq (BM) = 0.18 x (D/2) x 1000/100
= 0.18 x 550 x 1000/100
= 990 sqmm/m
AstPrv = #13 @ 125 C/C
  = 1013.44 sqmm/m
 
Top Reinforcement Along Column-B
D = 1100 mm
AstReq = 1980 sqmm/m
AstPrv = #16 @ 100 C/C
  = 1985.6 sqmm/m
       
Design for One Way Shear:
Along Column-D
Ppile = Capacity of pile
  = 1500 x 1.5
  = 2250 kN
       
Location of critical section is at d/2 from face of column
Section Location from column center = 870 mm
       
Data for Piles      
Pile No Load (kN) % covered Shear (kN)
P1 2250 70 675
P2 2250 70 675
 
Design Shear Force (Vu) = Max. of (Shear due to P1, P2)
  = 675 kN
Deff = 1040 mm
Beff = 900 mm
φVc = 525.81 kN
Vu > φVc, Hence Provide Shear Reinforcement
Vs = 198.92 kN
Vs Permisible = 2762.71 kN
AsvReq = 1000 X (Vs X 1000) / (fy X Deff)
  = 455.4 sqmm/m
AsvPrv = 473 sqmm/m
  = 2L-#10 @ 300 C/C
Vs Capacity = 206.61 kN
Vu < φVc+Vs Capacity  Hence Ok
 
Along Column-B
One way shear check do not applicable for 2 pile pile-cap design  
 
Design of Face Reinforcement:
AsfrReq = SFR % X D X Beffsfr
= 0.05 X 1100 X 500 / 100
= 275 sqmm
Asfr Prv = 4-#10
= 284 sqmm
 
Check for Load Transfer from Column to PileCap
Critical Load Combination : [20] : 1.2 (LOAD 1: LOAD CASE 1) +(LOAD 2: LOAD CASE 2) -(LOAD 4: LOAD CASE 4 EQ-Y)
P = 2085.62 kN
A2 = 0.49 sqm
A1 = 2.16 sqm
Base Area = 2.16 sqm
A1 < Base Area  
Modification Factor = SquareRoot(A1/A2) < = 2
SquareRoot(A1/A2) = 2.1  
Thus, Modification Factor = 2  
Φ1Pnb = Φ1 x 0.85 x Modification Factor x A2 x Fck x 1000
  = 0.65 x 0.85 x 0.49 x 2 x 20 x 1000
  = 10829 kN
Φ1Pnb > P, Hence Safe.