Question

S. Al-Martini, PhD, P. Eng. Question No. 5 (35minutes) 19 marks) As shown in the figure, a 9-ft 6-in square footing supporting an 18-in. -square tied concrete column and it is subjected to service dead load 225 kips, and service live load 175 kips. column is a typical interior column in a building. Assume normal-weight concrete.. soil pressure (ga) 5000 psf (5 ksf), f'e for column 4000 psi, f's for the footing lsteel 60, 000 psi. The density of the soil 100 Ib/ft3 and the density of concrete 150 The 3000 psi, f oncrete cover 4in (from the bottom of the footing to the centre of steel, i.e. d h -4in). A . s shown in the figure, the bottom of the footing is to be 4 ft below the finished ground surface Assume the thickness of the footing (h)-20 İn., check that this thickness is satisfactory for the two-way shear only. 2- If this thickness (h-20 in.,) is not sufficient, propose a thickness that satisfies the two-way- 1. shear requirements and prove that it is satisfactory. 18" square column Finished ground line 4'-0" 95 12

Answer 1

olo squan 6,レ Thicuness depth Commonuy deteimined based on tuoo uDy pu tuwo woy/punching shear on the critical perimete iven h: 20", thicrne ss booting Shear boyce (Vu) upward pressure-(thal acting uth in the critical perimetey upword pre sSure cased by the etor load (gu) = 2(DL)+16(LL ) Avca booting -1.2[125) -H-61145) 556 匸6.09 K/ 500-6y kips one

shea unching Shear -for Two- 351553 2sub L 485 thi t nen d=16" 2) Shear so ve have to incycare the thictnen jdopth Sat itachory for two way not Let Assume de vc .: e7iven thickne sc 8 boot in, es (h=20,n) is not subbicient to Sat?왑ies the tuo Shear Yeguiveme nts co Proposed Value 27