Design a simply supported I-Section beam:

Design a simply supported I-Section beam of 8 m span carrying a uniformly distributed load of 45 kN per meter. The compression flange may be assumed laterally supported throughout its length (f_y = 250 MPa).

Solution

Maximum BM = wl²/8 = 45x8²/8 =360kNm

In case of laterally supported flanges of beams:

σ_bc= σ_bt = 0.66 f_y = 0.66 × 250 = 165 MPa

Required section modules Z_x = 360 × 10⁶/165 = 2.182 × 10⁶ mm³ = 2182 cm³

From tables we select a section ISMB 550 (@ 103.7 kg/m) for which Z_x = 2359.8 cm³, Z_y = 193.0 cm³, t_f  = 19.3 mm, t_ω = 11.2 mm, B = 190 mm.