Question

1.Design the longitudinal and shear reinforcement for a 300mm x 400mm column support.The characteristic strength of concrete is 30KN/mm2 and of the steel reinforcement is 460 N/mm2 and 250N/mm2 for the links.The fire resistance requirements is 1 hour for all column.The self weight of concrete is 24KN/M3,the ultimate axial load N=950KN.

Answer 1

Solution:

Given column Dimension: (300x400) mm. f'c=30N/mm². fy=460 N/mm² • Fire resistance = 1hr....cie. Nominal cover=40mm). Ultmate Axial Load = Pu=950KN. solution: where, opu = $x[0.85 fé (Ag-Ast) + fy.Ast]. -0.65*(0-80)x[0.85 f'e. (Ag-Ast) + fy. Ast] Ag - Crooss Area = 400X300 = (120x103) mm? Ast = steel Area, Ac = concrete ara - Ag-Ast. 950 X10°=0.52 (0.85x30x (12x102-A549+4 60xAst]. 950x30 (30 306000 - 25-50 Ast + 460A5t). 0.52 - 1-8269x100 = 306000 + 434.50 Ast. 2.1.52 09X106 = 484-50 Ast. Ast = 3500.84 mm Use, 22 mm diameter bars. ... No. of bars Art 3500.34 9.21910 Nos. T24x8² / 4X (2272

O . 6 Links !. Provide test i) Diameter of Tie bars 6mm. .- (minimum). • 1/4x0 = V4X22 = 5.smm. Ti) modemum te spacing :). .48 (He) = 48x6 =288 mm. 16% (º longitudinal) = 16X22= 352mm. • Least lateral Dimension of column=300mm So, provide 275mm of 275mm of spadng been her. 6 Detailing checks as Steel %. = Ast 8500.34 Ag 300X400 (Beth lyto 6%). • No.of bars = 10 No. > 4NOS --- OK, · Main Bar spaung = (400-2X501-4X22) = 70.66 mm. ---OK. a Reinforcement Detailing :- ) *100 = 0.91"--ok. cover bar. 3 Tie : 6 mm 24/5 dc , mm 300mm. Moun Bars!). dammo - 10 NOS. 400mm