Question

Steel Design

1. Given: a. A 16 FT Column of A992 Steel b. Factored Axial Load (Pu) equal to 350 kips c. Weak Axis Fixities Rotation fixed and translation free at the top. ii. i. Rotation fixed and translation fixed at the bottom. d. Strong-Axis Fixities i. Rotation free and translation free at top ii. Rotation fixed and translation fixed at bottom. e. Limit Column Selections to Table 4-1 of AISC Steel Manual. f. Show full Calculations are required for final validation

Answer 1

GIVEN DATA Grade of steel Factored Design Load A 992 350 kips Pu- Restrain Along x direction Unsupported Length of column Bottom End Top end 16 ft : fixed ree Along y direction Unsupported Length of column Bottom End Top end 16 ft fixed moveable with fixed rotation CALCULATIONS Yield stress of steel Modulus of Elasticity of steel 50 ksi E 29000 ksi Effective length factors 1.2 Since the restraints along the two axes are different, buckling along weak axis controls if Otherwise, buckling along strong axis controls. Assuming r, /r, 2 Kury = 100 KL - 1.3221.5 Note h, <1.5, F (0.658F For 0.877 Therefore, critical stress, Far 24.06 ks Therefore, required area of cross-section, 350/0.9 x 24.06 16.16 in2 Select W 12x58

CHECK CAPACITY Properties of Steel section Column Section Gross area of cross section, Radii of gyration, W 12x58 17 in rx = 5.28 in ry 2.51 in K,L 2x( 16 x 12in)/5.28 = 72.727 K L 16 x 12 in/2.5 = 91.793 Since KLxfr Kylyry,Kyly/ry controls. 1.213 < 1.5 Note For λ、〈 1.5, F, = (0.6584° )F, 0.877 he Therefore, critical stress, Fa27.01 ksi Hence, Design axial strength of column, 0.9 x 27.01 x 17 413 kips 50 kipsP Hence SAFE Thus, the member size is OK