Question

1- Calculate the design moment strength of the given beams for f=60,000 psi and f =4,000 psi. (in all question) 12" 110 10-

Answer 1

For sa section we know that design &mna dAsty (d-a). where As, 24110 ü moment strength - Pmn. 2* 1.2.701n ; 2.54in.. we know that depth of neutral anis a: Asty where be width of 0.85fc'b. compression block. u brizin az 2:54x 60,000 0.85x 4000 x 12" - 3.7353 in qmns 0.90% 2.5 4x 60,000~ ( 22 - 3.7353) A6 1353.126 lb-in 27611353k in amm= 230. 112 koftol Note: d= depth of beam 4416 +2 --22in For Rectangular hollow section dmn. o As fy (d-a). As = 54111 à 5x1:58 int = 7.8in. compression for ce (C) = Tensile force (1) 0.85 fc'ba. - As ly. I a. As fy 7.8x60,000 0.85xfi'b 0.85x4000x 18 Depth d= h-3in = 30-3 = 27in Anna 0.90x 7-8 x 60,000x (27-799) - 9261310 ebrin 57.6510 X

Mna 9761.310 k-in 7 813.44 25k-ft B for Inverted to section depth of neutral anis (a). compressive force (C). Tensile force (T) 0.85 fcba = As ty. As; 4 #10, i ux 1.270 - 5.08int ar Asty - 5:08x60,000 - 11.206 in. 0.85x4000x8 4 dmn. o.Adx Asty (d-as). = 0.90* 15.08x60,000 * (25 - 11.206) 2 5321001.126 abrin ; 5321.001 Iin 443.ulb kaft