Question

Structural steel buildings frequently are designed with diagonal bracing systems to resist lateral loads (horizontal forces resulting from wind or earthquake loadings). A certain bracing system is subjected to the following loads: dead load, 13.3 kips, occupancy live load -6.9 kips, roof live load – 1.3 kips, snow load – 1.3 kips, wind load – 150.6 kips, and earthquake load – 161.1 kips. a. Determine the required factored load capacity for LRFD. Which load combi- nation controls? b. Determine the required ASD load capacity. Which load combination controls?

Answer 1

Date Page 1 ERRO Criven - Dead load (0) =_13_3 Kips live lead (L) 6.9 Kips roof live lead (1) 1.3 kips snow load (5) 1.3 kips Wind lead (W) 150 6 kips Earthquake load te) 16141 kips. 13 LRED_load combination 1 Pu = 1.40 1.42X 133 = 18.62 kips 1. Pu 1.2 D + 1.6L t 0.5 Ly 24.2813.3)+(1.6X_6-9)+(0.5 x 1.3) 227.65 kips 3 Pu 2 1.2 D + 1.6L+0.55 = (1.2 x 13-3) +f16x6.9) + (0.5 x 1,3) 2 27.65_kips 4 Pu = 1.20 + 1.6 Lr + 0.5W 20+ (2x13.3) + (1.6 x 1.3) +(0.5 x 150.64 = 93.34 5) Pue 1:20+W + 2.5 X{Lr or s) = (1.2 x 13.3) +(1.50.6) + (0.5 x 1:3) 2 167.2) kips 7 Pu= 1.2D + E + 0.25 (1.2 X 13.3) + (161.1) +(0.2 x 1:3) 177.32 kips CS Scanned with CamScanner

Date Page. 7 Pu 0.90t W 0.9 x_13.3 + 150.6 _162.57_kips 8 Pu O.9 D + E 0.9X_13-3 + 1611 173.07 kips Governing load facta 177.32_kips b] ASD Loadcombination I D = 13.3 7 DIL 13.3 + 6.9 20.2 kips 37 0+ (harors) a 13.3 + 1.3 64.6 Kips 4 D +0.75 L t 0.75 (Ly or 5) - 13,3_+(LZS Y 6.9)+0.75 X 1-3) 19.45 kips 5)_D.+ 26 b + = 13.3 4 +(0.6 x 150,6)= 103.66 kips 0 DtOFE 13.3 +67x161.1) = 126.1 kips 1 D+0.754 +0.75x(0.5 6) +0.75 flex ors) 13.3 +0.7.5x629)+(0.75 X 0.6 x 150, 6) + 60.75 x 1:3) 87. 22 kips CS Scanned with CamScanner

Date Page 8) D+ (0.75 L)+(0.75 x 0.7xE) + 0.75 (5) 21.3.3 +60_75 X 6.9) + (0.75 x 0.7x 161.1) +(0.75X1.37 104.03 Kips 7 0.6D to. 6 W (0.6 x 13.3)+(0.6 x 150.6) = 98.34__kips lo] 0.6 D+ 0.7 € (0.6 x 13.3) +0.7 x 161.1) 120.75 kips Governing Loada 126.1 kips J LRED Governing factored load = 177 32 kips 4 load combination No. I is control 1) ASD 126elkips & load combination No. 6]_is_control Governing lead CS Scanned with CamScanner