Engineers Must Know About Reinforcement and Steel Bars Clear cover to main reinforcement in Footings : 50 mm Raft foundation Top : 50 mm Raft foundation Bottom/ sides : 75 mm Strap Beam : 50 mm Grade Slab : 20 mm Column : 40 mm (d>12mm) 25 mm (d= 12mm) Shear Wall : 25 mm Beams : 25 mm Slabs : 15 mm or not less than diameter of the bar. Flat Slab : 20 mm Staircase : 15 mm Retaining Wall on Earth : 20/ 25 mm Water retaining structures : 20 / 30 mm Sunshade (Chajja) : 25 mm Hook for stirrups is 9D for one side No. of stirrups = (clear span/Spanning) + 1 For Cantilever anchorage length for main steel is 69D “L” for column main rod in footing is minimum of 300mm Chairs of minimum 12 mm diameter bars should be used. Minimum diameter of dowel bars should be 12 mm Lap slices should not be used for bar larger than 36 mm. In steel reinforcement binding wire required is 8 kg per MT. Lapping is not allowed for the bars having diameters more than 36 mm. Minimum number of bars for a square column are 4 and for circular column are 6. Longitudinal reinforcement should not be less than 0.8% and more than 6% of gross C/S. Weight of rod per meter length = d2/162 where d is the diameter in mm All reinforcement shall be free from mill scales, loose rust & coats of paints, oil or any other substances. Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.
Posted on: Mon, 01 Dec 2014 11:01:19 +0000
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