Question

Q4. A square pad footing supporting a column at the centre is shown on DWG-07 on page 7. The design parameters of the footing are: = = Side length of the footing, L Overall depth of the footing, h Column width, c Cover to reinforcement Preferred bar size (both directions) Dead load from column, GK Imposed load from column, Qk 3650 mm 800 mm 600 mm 75 mm 20 mm 1300 kN 900 KN Il (a) Design the bending reinforcement for the footing. (18 marks) (b) Check the shear capacity at the perimeter of the column face for the footing (4 marks) (c) Check the shear capacity at 1.0d from column for the footing. (4 marks) (d) Check the resisting punching shear for the footing. (4 marks)

Answer 1

ANSWER:-------

Given L= 3650mm h=800mm 600mm Gk = 1300KN QK = gookn Preferred bar size=20mm Cover to renforcement = 75 mm too bang through column= 1300 +900 2200 kn load acting on 2200 x 10 3650 x 365 on me 2200 X10 3 13133.9500 2 1 66 wl mm 166 2 KN Consedering shear area - I & calculating Moment (M) M - 0.166 x 1x ) 150-600) 2 n 166.2x (3650 166. 2x (3050 )? 166. 2 x 2325625 M - 193.25 kal-m

193.25x106 X 4 d Calculate Area of steel, Compressive force = Tensile force 0.36 x fck XX u b = 0.87 fyx Ast 0.87X fy Ast 0.36 x fckx bd where ty = 415 N/mm for fe uis steel fck a = 30 Nil mm (M.30 grade Concrete) Me = 0.87 fy Asta (1-0.42% (0.87 fy & Ast 0.367fckxbxd whered 4- Cover renforcement 800 75 d 7 25mm 193.25 x 186 = 0.87X 415 * Ast X 725 (1-0.42% 5 (1-0.42 x 0.87X YIs Ast 0.36x30x10 x 725 = 193.250106 = 361.054 Ast x 725 (1-042 (4.611 X 105) Ast) 193-25 X10%= 361.05 x Ast * +25 (1–1198 x 10) Ast) 361.05 x Astx725 (0.99 x Ast) 6 193:25 X 106 361.054 725 80.99 (Ast) • (457) 820-29 Ast. - 820.29 mm² mast % Ast 20.29 1000 x 725 X 100 l. Asta 0.111

Spacing - - - X (20) * X 1000 820.29 0-78UX 400 X 1000 820.29 ~ 300 mm 20mm dea 382.30 Provide bar @ 300mm ck, spacing both direction. check for shear Capacity at the perimeter of column face for the footing Yv = w/ L²_(²) 2(c+C) xd 0.1662X ( (36505- (70) 2(600 + 600) x 725 0.1662 * (13322500 - 490000) 1 2 x 1200 x 725 2130195 1740ooo Tv 1.224 N/mm² > Tc 0.29 N / man (Wot safe) c) check for stear Capacity at lod from Column for fotog 0.1662 x 3 650 x 885 3650 X 725 53686 7.5 2646250 2 0.20 (footing is safe)

d) check for punching shear for footing w (L² - ((+ d)) Tv= u x (k+d) xd 16(3:50) 65+725)) ux (600*726) 725 0.1662 (13322 500 - 1455625) ux 1325 Y 725 0.1662 X 11566875 384 250o ( 0.500 N/mm2 Tv + Puiper ie (kß oirs Jfck - IX 0.25% 530 = 1.37 N/mm2 (safe)