d/2 d/2 M 0.138f bd2(b2800 mm) 0 ck 136.36 106 d= (M-20 grade concrete) 0.138 20 2800 d=132.83 mm 140 mm Using 12 mm (diameter) main bars. 12 Overall thickness of slab = 140 15 161 mm 170 mm 2 12 Depth (along longitudinal direction) = 170 15 150 mm 2 Depth (along longitudinal direction) = 150 12138 mm k) Thickness of drop from maximum –ve moment consideration Thickness of drop from consideration of maximum –ve moment any where in the panel. Max –ve BM occurs in the column strip = 166.6 KNm M 0.138f bd2 u ck 1.5 166.6 106 0.138 20 1400d2 d 254.3 mm Say 260 mm. Use 12 mm bars 12 Over all thickness of flat slab:
D 260 15 281 mm 2 2340 mm 1300 mm d/2 450 300 mm 5.6 m 1.3 m 2200 d/2 300 mm 6.6 m 18 0 0