Design of Shallow Foundation (Isolated Footings)

Footing size

Column load 2000KN

10% OF FOOTING SELF WT= 2000X10/100=200KN

Axial load on footing = 2000+20= 2200KN

Area of footing

A= 2200/150 = 14.66m2

B=L=√14.66= 3.383m say =B=L=3.9M

Net upward pressure

=2200/(3.9x3.9)=144.64x1.5=216.96kn/m2

Bending moment

load on critical section= 4x216.96=867.84kn/m

BM=WL^2/2=867.84X1.75X1.75/2=1328.88KNM

Depth of footing

Mu= 0.133fckbd2 for fe 500

d=√(Mu/(.133fckb)

=√1328.88x10^6/.133x25x4000

=315.99mm2 say 650mm

cover=50mm

overall depth of footing= 650+50+16/2= 708mm say 750mm

d=750mm

Reinforcement req

Mu/bd2= 1328.88x10^6/4000x700^2=.678 say .7 for fy= 500 pt= .167% from sp 16 table 3

Ast= .167x4000x700/100=4676mm2

no of bar= 4676/201=23.26 say 24 nos

24x201= 4824mm2

spacing = 201x4000/4824=166.6mm c/c

Check for one way shear

shear force= 216.96x(4-.40/2-.7=238.6kn

100ast/bd= 100x4824/4000x700=.172

Tv= v/bd= 238.6/4000x700=0.085n/mm2