ideCAD Structural controls and reports these requirements automatically.


Symbols

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)


In order to restrain the lateral-torsional buckling of structural steel designated as moderately ductile members, stability bracing should be provided.

According to Equation D1-2, the bracing of moderately ductile beam members should have a maximum spacing of:

Lb=0.19ryE/Fy