Bending Capacity

The effective length of a beam can be controlled by setting the criteria with the Criteria-Design Defaults command. The specifications of CAN/CSA S16-01 have been implemented with the following modifications according to the Structural Stability Research Council (SSRC), "Guide to stability Design Criteria for Metal Structures", Galambos, 1998.

For cantilever beams, the effective length is taken as 1.5 times the unbraced length. This assumes the cantilever tip is restrained against torsion. Omega 2 (ω2) is taken as 1.0 for cantilevers.

For unsymmetrical flange sections the following equation per SSRC has been implemented to calculate the lateral torsional buckling capacity:

M_{c r} = \frac{ω 2 E}{K_{y} L} [\sqrt{E I_{y} G J} (B_{1} + \sqrt{1 + B_{2} + B_{1}^{2}})]

where

B₁	=	$\frac{π β_{x}}{2 K_{y} L} \sqrt{\frac{E I_{y}}{G J}}$
B₂	=	$\frac{π^{2} E C_{w}}{{(K_{y} L)}^{2} G J}$
β_x	=	$0.9 d^{'} (2 \frac{I_{y c}}{I_{y}} - 1) [1 - {(\frac{I_{y}}{I_{x}})}^{2}]$
d'	=	distance between center of the top and bottom flange
I_yc	=	The moment of inertia of the compression axis about the section minor axis.

For all sections of class 3 the capacity of the section is considered to be the compression flange section modulus multiplied by the design yield strength.

Channels are designed using the symmetrical provisions of the design specification with the assumption that loading is through the shear center.

The loads applied along the length of a section considered as being applied at the shear center.