Pile CAP Design Example + 2 piles
3
Project Job Ref. Section Sheet no./rev. 1 Calc. by C Date 3/25/2015 Chk'd by Date App'd by Date RC PILE CAP DESIGN (BS8110:PART1:1997) TEDDS calculation version 2.0.02 b P 1 P 2 s L e Loaded width - x e x e x 2 Pile Cap, height h Pile Cap Design – Truss Method Design Input - 2 Piles - No Eccentricity Number of piles; N = 2 ULS axial load; Fuls = 31500.0 kN The ultimate load per pile; Fuls_pile = Fuls/2 = 15750.0 kN Characteristic axial load; Fchar = 21500.0 kN The characteristic load per pile; Fchar_pile = Fchar/2 = 10750.0 kN Pile diameter; = 1800 mm Pile spacing; s = 4500 mm Pile cap overhang ; e = 200 mm Overall length of pile cap; L = s + + 2 e = 6700 mm Overall width of pile cap; b = + 2 e = 2200 mm Overall height of pile cap; h = 3000 mm Dimension of loaded area; x = 1500 mm; (parallel to pile cap) Cover Concrete grade; fcu = 40.0 N/mm 2 Nominal cover; cnom = 100 mm Tension bar diameter; Dt = 32 mm Link bar diameter; Ldia = 10 mm Depth to tension steel; d = h – cnom - Ldia - Dt/2 = 2874 mm Pile Cap Forces Compression within pile cap; Fc = Fuls/(2 sin()) = 20002.5 kN Tension within pile cap; Ft = Fc cos() = 12330.4 kN Compression In Pile Cap - Suggested Additional Check Check compression diagonal as an unreinforced column, using a core equivalent to pile diameter Compressive force in pile cap; Pc = 0.4 fcu 2 /4 = 40715.0 kN PASS Compression Cl. 3.8.4.3
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This document presents how to design a pile cap using BS8110.1997 British code. CSC TEDDS was used to generate the calculation. Strut and tie method was used. Once the structure has been analysed and designed, the user can edit any pile cap so to view its dimensions and reinforcement.The pile caps editor also allows the user to change the type of pile cap, modify its dimensions and reinforcement, and select the type of pile. Once the specifications have been introduced by the user, the editor can check to see whether the pile cap complies with the modifications that have been introduced or design the pile cap. The design process consists of three options:
Transcript of Pile CAP Design Example + 2 piles
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Project Job Ref.
Section Sheet no./rev.
1
Calc. by
CDate
3/25/2015Chk'd by Date App'd by Date
RC PILE CAP DESIGN (BS8110:PART1:1997)TEDDS calculation version 2.0.02
b
P1 P2
s
L
e
Loaded width - x
ex
ex
2 Pile Cap, height h
Pile Cap Design Truss Method
Design Input - 2 Piles - No EccentricityNumber of piles; N = 2ULS axial load; Fuls = 31500.0 kNThe ultimate load per pile; Fuls_pile = Fuls/2 = 15750.0 kNCharacteristic axial load; Fchar = 21500.0 kNThe characteristic load per pile; Fchar_pile = Fchar/2 = 10750.0 kNPile diameter; = 1800 mmPile spacing; s = 4500 mmPile cap overhang ; e = 200 mmOverall length of pile cap; L = s + + 2 e = 6700 mmOverall width of pile cap; b = + 2 e = 2200 mmOverall height of pile cap; h = 3000 mmDimension of loaded area; x = 1500 mm; (parallel to pile cap)
CoverConcrete grade; fcu = 40.0 N/mm2
Nominal cover; cnom = 100 mmTension bar diameter; Dt = 32 mmLink bar diameter; Ldia = 10 mmDepth to tension steel; d = h cnom - Ldia - Dt/2 = 2874 mm
Pile Cap ForcesCompression within pile cap; Fc = Fuls/(2 sin()) = 20002.5 kNTension within pile cap; Ft = Fc cos() = 12330.4 kNCompression In Pile Cap - Suggested Additional Check
Check compression diagonal as an unreinforced column, using a core equivalent to pile diameter
Compressive force in pile cap; Pc = 0.4 fcu 2/4 = 40715.0 kNPASS Compression
Cl. 3.8.4.3
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Project Job Ref.
Section Sheet no./rev.
2
Calc. by
CDate
3/25/2015Chk'd by Date App'd by Date
Tension In One Truss MemberCharacteristic strength of reinforcement; fy = 500 N/mm2
Partial safety factor for strength of steel; ms = 1.15Required area of reinforcement; As_req = Ft /(1/ms fy) =28360 mm2Provided area of reinforcement; As_prov = Ast = 33778 mm2
Tension in truss member; Pt = (1/ms fy) As_prov = 14686.3 kNPASS Tension
Cl. 3.11.4.2
Max / Min Areas Of ReinforcementMinimum area of tension steel; Ast_min = kt Ac = 8580 mm2Maximum area of tension steel; Ast_max = 4 % Ac = 264000 mm2
Area of tension steel provided OKCl. 3.12.6 & Table 3.25
Shear
Applied shear stressAplied Shear stress; V = Fuls / 2 = 15750.0 kNWidth of pile cap shear plane; bv = min( b, 3 ) = 2200 mmDesign shear stress; v = V / (bv d) = 2.49 N/mm2Allowable shear stress; vallowable = min ((0.8 N1/2/mm) (fcu ), 5 N/mm2 ) = 5.00 N/mm2
Shear stress - OKCl. 3.4.5.2
Design concrete shear strengthDetermine concrete shear strength on the section at distance / 5 inside face of pile:
Cl. 3.11.4.3 & fig. 3.23
Shear stress - Table 3.8;vc_25 = 0.79 r1/3 max(0.67, (400 mm/d)1/4) 1.0 N/mm2 / 1.25 = 0.34 N/mm2
Shear stress - Cl. 3.4.5.8 & fig. 3.5; vc = vc_25 ( min( fcu, 40 N/mm2 ) / 25 N/mm2 )1/3 = 0.40 N/mm2Spacing; av = min( 2 d, max( ( s / 2 - / 2 + / 5 - x / 2 ), 0.1 mm )) = 960 mmEnhanced shear stress; vc_enh = min( vallowable , 2 d vc / av) = 2.41 N/mm2
Concrete shear strength - NOT OK, provide MINIMUM links
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Project Job Ref.
Section Sheet no./rev.
3
Calc. by
CDate
3/25/2015Chk'd by Date App'd by Date
Deflection Check (Cl 3.4.6)Redistribution ratio; b = 1.0Design service stress in tension reinforcement; fs = 2 fy As_req /(3 As_prov b) = 279.9 N/mm2Modification for tension reinforcement;
factortens = min( 2, 0.55 + (477 N/mm2 - fs)/(120 (0.9 N/mm2 + Ft /(bd )))) = 1.126Modified span to depth ratio; modfspan_depth = factortens basicspan_depth = 22.5Span of pile cap for deflection check; Ls = 4500 mmActual span to depth ratio; actualspan_depth = Ls /d = 1.57
PASS - Deflection
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