Question

Design a square concrete column footing to support a 500-mm x 500-mm reinforced concrete column. The center of the column and footing must coincide.
Loads: ???=350 ??, ???=480 ??, ???=100 ??−?, ???=130 ??−?
Column Design Criteria: ??′=28 ???, ??=400???
Footing Design Criteria: ??′=28 ???, ??=400???, ??=175 ???,??=1.50 ?, ??=16 ??/?3,??=24 ??/?3, ??=20 ??, assume a thickness of the footing of 500 mm.

Answer 1

load PDL = 350KN

PLL = 480KN

SBC = 16 X 10=160 KN/m3

load combination = 1..5( 350 + 480) =1245 KN

area of footing = load on footing /SBC =1245/16 =7.781 m2

size of footing =3 x 3 m

rea provided = 3 x 3 = 9 m2

net upword pressure

critical section of the footing

critical section of footiing@ face of column from the edge of footing

3000/2 - 500/2 =1250mm

bending moment

net moment = MDL + MLL = (100 + 130_) x 1.5 = 345 KNm

provided total depth as 1.5 m

reinforcement

=0.0153%

=674.73 mm2

no of bar =

CLEAR SPACING =(3000-50-50-10-10)/ No of bar - 1 =1440mm

more so not ok

reduce bar size 12 mm

CLEAR SPACING =(3000-50-50-10-10)/ No of bar - 1 =550 mm

one way shear

Vu - up ward pressure x area of critical section = 207.5 x 3 x 0.6 =372.6KN

safe for shear