Asgarian - Civil Engineering Dept. of K.N.Toosi University of Technology
Pirmoz - Civil Engineering Dept. of K.N.Toosi University of Technology
Saedi Daryan - Civil Engineering Dept. of K.N.Toosi University of Technology

Since now, lots of experimental and numerical studies have been done to investigate nonlinear behavior of I-shaped steel beams but there is noclear understanding of inelastic behavior of castellated steel beams. This paper presents nonlinear behavior of such beams under moment gradient loading and investigates the effect of beam length on overall response of this type of beams. For this purpose several refined 3-D finite element (FE) models subjected to moment gradient loading developed using solid elements, and their overall behavior is studied. The models have variable length and different bracing conditions. Analyzing the models under mentioned loading showed a reduction in ultimate rotation capacity for castellated beams respect to plane-webbed beams for longer beams. Also results of analyses showed that in bracing length near to plastic bracing space local instability of flanges occurs earlier than local buckling of web posts so due to full bracing of top and bottom flanges yields a greater ductility and moment capacity.

Moment gradient, finite element method, Ductility, Castellated beam