MODELING STRATEGIES OF FIBER MODELS FOR COMPOSITE STRUCTURAL MEMBERS: ELEMENT MESH AND SECTION DISCRETIZATION

This paper presented parametric studies on modeling strategies of a fiber beam-column model for nonlinear analysis of composite structural members to balance the accuracy, efficiency and numerical stability of the fiber model. The rational element mesh and the efficient section discretization scheme were two main focuses. It was recommended the rational element mesh size be selected to be about half of the mid-span equivalent plastic hinge length of a simply supported member when the standard displacement-based fiber element with one-point integration scheme was adopted. Such mesh schemes can accurately capture the sharp jump of the curvature at the plastic hinge region, and can also effectively overcome the pathological mesh-sensitivity problem caused by strain softening. In addition, the midpoint integration rule with 8, 24 and 32 uniformly distributed fibers for composite beam, circular concrete filled steel tubular (CFST) and rectangular CFST sections, respectively, offered sufficient accuracy for the hysteretic behavior of composite members under complex cyclic load histories.