ideCAD Structural controls and reports these requirements automatically.


ho = distance between flange centroids, in. (mm)
Fy = Specified minimum yield stress
Ry = Ratio of the expected yield stress to the specified minimum yield stress, Fy
Mr = Required flexural strength, kip-in. (N-mm)
Lb = Length between points which are either braced against the lateral displacement of compression flange or braced against twist of the cross-section, in. (mm)
ry = Radius of gyration about y-axis, in. (mm)
Z = Plastic section modulus about the axis of bending, in.3 (mm3)
αs = LRFD-ASD force level adjustment factor 1.0 for LRFD and 1.5 for ASD
E= Modulus of elasticity of steel = 29,000 ksi (200 000 MPa)

According to Equation D1-2, for structural steel beams should provide to have a maximum spacing of Lb = 0.095ryE/(RyFy)