Steel Columns, Beams & Bolts

Worked: a 15 ft column

A wide-flange column, F_y = 50 ksi, A_g = 14.4 in², r_x = 4.35 in and r_y = 2.50 in, is pinned at both ends over 15 ft with no intermediate bracing. The weak axis governs: KL/r = 180/2.50 = 72, below 113. F_e = π² × 29,000/72² = 55.2 ksi. F_cr = 0.658^(50/55.2) × 50 = 34.2 ksi. φ_cP_n = 0.90 × 34.2 × 14.4 = 444 kips.

A ¾ in Group A bolt with threads in the shear plane (F_nv = 54 ksi, A_b = 0.442 in²) carries 0.75 × 54 × 0.442 = 17.9 kips in single shear.