footing design 11

8/3/2019 Footing Design 11

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DATE:-22-07-2008Name of Client : - BPCL KOCHI REFINERYBOILER SUPPORTING STRUCTURE FOUNDATION:-

Footing Design(footing 7)a)Size of footing

Size of column= 775 x 775 = 0.600625= 3.24

Load on column= 404.88 kN = 1.05= 8

Moment about its major axis= 2.4 kNm = 22.17075 KN= 14.07 KNGrade of Concrete M 30 0.3155 = 36.24075 KN

Grade of Steel Fe 415

Safe bearing Capacity of Soil 150 kN/m^2 at depth 1.5 m(25% of increase allowable bearing pressure) S.B.C calculation

(P-7,T-1,IS1893(part-4):2005) actual S.B.C. 120 kN/m^2a) Size of Footing : (25% of increase allowable bearing pressure) 30 kN/m^2

Column Load= 404.88 kN (P-7,T-1,IS1893(part-4):2005)self wt. of footing= 40.488 kN Increase bearing capacity at 1.5m depth=xD= 27 kN/

Total= 445.368 kN 177 kN/m^

Area requi red for Axial load only= 2.97 m^2

If x is the projection of footing from the column face

x = 0.47 mWidth of the Footing= 1.72 1.8 m

For determining Length Trialand error method should be emplyed

P = 445.368 kNM = 2.4 kN-m

unit weight of soil

Vertical loadtotal load

load due to overburden s Area of pedestal Area of footingHeight of pedestal

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Trial L B A Z P/A M/Z pmax pmin1 1.8 1.8 3.24 0.97 137.46 2.47 139.93 134.992 2 1.8 3.6 1.20 123.71 2.00 125.71 121.713 1.8 1.8 3.24 0.97 137.46 2.47 139.93 134.99

Adopt Size of footing 1.8 x 1.8

b) Net upward pressuresp max = 127.43 kN/m^2p min = 122.49 kN/m^2

Net projection of footing form short face 0.5125 mprojection of footing form long face 0.5125 m

pressure at short face of column 126.02606 kN/m^2

c) Moment calculations :Mx= 16.67 kNm

Mux= 25.01 kNmMy= 29.54 kNm

Muy= 44.31 kNmd) Moment steel :

Depth Req. for flexureC = 4.14d = 57.933182 mm

Try over all Depth 450 mmdx = 394 mmdy = 382 mm


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Steel parallel to longer directionMu/bd^2 = 0.09

pt = 0.12 0.12 % of minimum Steelpt = 0.12

Ast = 858.132 mm^2Provide 10 mm

Spacing = 164.6610 mm @ 125 c/c

Steel Provided Ast = 1130.4 mm^2Steel parallel to shorter direction

Muy/bd^2= 0.17pt = 0.09 0.12 % of minimum Steel

pt = 0.12 Ast = 825.12 mm^2

provide 10 mmSpacing= 171.25 mm

Provide 10 mm @ 125.00 c/cSteel Provided Ast = 1130.40 mm^2

provide minimum reinforcement in top 10mm# - 200mm c/

DATE 22 07 2008


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DATE:-22-07-2008Name of Client : - BPCL KOCHI REFINERYBOILER SUPPORTING STRUCTURE FOUNDATION:-e) One -Way Shear

bout x1 - x1Distance of Critical Sectionfrom edge of Footing (x) = 118.5 mm 0.1185 mStress at Critical Section = 127.107 kN/m^2

V = 27.15 kNVu = 40.72 kNTv = 0.06 N/mm^2

100As/bd = 0.16Tc = 0.29 N/mm^2 SAFE

bout y1 - y1Distance of Critical Sectionfrom edge of Footing (x) = 130.5 mm 0.1305 m

Stress at Critical Section = 127.07 kN/m^2V = 29.89 kN

Vu = 44.84 kNTv = 0.07 N/mm^2

100As/bd = 0.16Tc = 0.29 N/mm^2 SAFE

f ) Two - Way Shear :c = (Short side of Column)/(Long Side of Column) = 1

Ks = 1.5 < 1Ks = 1Tc = 1.3693064

Design Shear Strength = 1.369306 N/mm^2Two Way Shear Along line ABDistance of Critical Sectionfrom edge of Footing (x) = 315.5 mmShear Stress at critical Section = 126.57 N/mm^2

V = 59.48 kNVu = 89.22 kNTv = 0.19 N/mm^2 SAFE

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:- - -Name of Client : - BPCL KOCHI REFINERYBOILER SUPPORTING STRUCTURE FOUNDATION:-

all dimensions are in mm

a = 197 f = 77b = 315.50 g = 512.c = 394 h = 77d = 118.5

e = 512.5

p1= 122.49 KN/m 2

p2= 126.03 KN/m 2

p3= 126.57 KN/m 2

p4= 127.11 KN/m 2

p5= 127.43 KN/m 2

x x2 x1

x x2 x1

y y

a b

c d

e f e

g

h

g

xx2 x1

p1 p2 p4p3 p5

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footing design 11

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