Effect of moment gradient on the local buckling behavior of flanged-cruciform flexural members

In this study, the effect of moment gradient on the local buckling behavior of flexural members with flanged cruciform section, being considered as an appropriate alternative to use in orthogonal moment-resisting frames is analytically investigated. A simplified residual stress distribution model for welded flanged cruciform sections is proposed and implemented in the experimentally verified, nonlinear finite element models and a wide range of web and flange thicknesses are assigned to evaluate the current AISC slenderness limits, employed for I-shaped sections in different moment gradient states.The results indicate that I-shaped section compact limits are safely applicable for short members with global slenderness (L/ry) in the range of 75-92, but the rotational and flexural capacity extremely decline as moment gradient decreases. In beams with slight gradient (long beams), flexural behavior is not dependent on the thickness of plates and the lateral-torsional buckling would be dominant failure mode in these beams

Keywords:

Flanged cruciform section , Local buckling , Residual stresses , Rotation capacity