l) Shear in Flat Slab The critical section for shear shall be at a distance d/2 from the periphery of the column/capital/ drop panel, perpendicular to the plane of the slab where d is the effective depth of the section (Fig. 2). The shape in plan is geometrically similar to the support immediately below the slab. check for shear stress developed in slab The critical section for shear for the slab will be at a distance d/2 from the face of drop. Perimeter of critical section = 4 x 2340 = 9340 mm V L L 0 1 2 1.5 15.45 [ (2.34)(2.34)] Total factored shear force:
= 1.5 15.45 [6.6 5.6-(5.47)] = 729.78 KN Nominal shear stress = V bd shear strength of concrete = 2 0.25 =0.25 20=1.11 N/mm c ck f 2 729.78 10 0.55 N/mm 9340 140 3 u v Permissible shear stress = v s c k (0.5 ), 0.848 k k s c c (0.5 0.848) k s 1.348 1 1 s 1 1.11 1.11 N/mm 2 v c safe design ok if 1.5 then the slab should be re-designed v c m) check for shear in drop ( ) (1.3 0.26) 4.89 m b D d 0 0 V=1.5 15.45[5.6 6.6- (1.3 0.26) ] 4 V 812.27 KN 2 812.27 10 0.683 N/mm 4890 260 3 v 2 Nominal shear stress : c ck 0.25 1.11 N/mm f 2 v c [safe in shear] 19