Question

1. A plain concrete footing is to be designed for a 400 mm reinforced concrete wall that supports a dead load of 187 KN/m including the wall weight and a live load of 79 KN/m. The base of the footing is to be 1.4 m below the final grade. The allowable bearing capacity is 189 Kpa, weight of soil is 15.82 KN/m3, fc’ is 28 Mpa, and concrete to be 23.5 KN/m3. Determine the:
   1. width of the plain concrete footing              (c) adequacy of the section
   2. allowable bending strength                        (d) allowable shear strength

Answer 1

() 400 mm wall, D2 = 187 DL = 187 Knim L = 79 Kolm 1.4 m below rsoil = 15.82 KN 1m3 Vc = 23.5 kN lm3 Allowable Sol Pressure z 180 kPa Assume 450 mm deep footing (d=360 nm) ve 189 - 450 X23.5 1000 Too x 15.82 1000 2 167.351 Kau ir a) width resuired 1 87 + 93 167.35 1.699 say am -". adopt adopt width of of 2m b) allowable bending & trength Yus la 2(187)+ 1.6(79) 2 175.40 knlm2

c) ademary of section Check for bending: 400 mm wall 1.4m below ta (0.7m) h=0.7m ㄴ 8.8m k a.sm o.um K Mu 175.4% 0. 7X0.7 2 KN-m 2 42.973 2 05 = 0 sxffles ba Es Ø Mn 6 = (0.6305) () (28) (400x360 (400x360) 725 2 Kn-m ~ 0 Mn >> My hence adecuate

allowable shear & trength and the ok > Vu for 400 mm width of froting 0.7 0.4 175.4 d 35.08 KN ✓ Nu () عد Ø Affe bb WiA 4 ton 6x110 28 x 400 x 700 a 118.5 KN Ww) 400 m 2 Vu hence sade Use 450 mm fooking

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