Nonlinear finite element failure analysis of bolted steel-concrete composite frame under column-loss

Abstract

This paper presents a detailed nonlinear finite element analysis of bolted steel-concrete composite frame in the scenario of middle column loss. The finite element model is developed based on ductile metal fracture model and concrete damaged plastic model. A method is proposed to apply the pretension loads on bolt in quasi-static analysis which is normally ignored. After calibrating the FE model against with the experimental results, a parametric study is conducted to investigate the performance of composite frame under column removal. The numerical results show that using stiffeners at column and increasing the rebar ratio in RC slab would improve the initial behavior of the models. The bolts with good ductility are suggested to be used in composite joint to develop the resistance potential of RC slab. Otherwise, premature fracture of bolt may be caused by the existence of RC slab. Increasing the beam depth or bolt-group depth would reduce the rotation capacity of the model. Since, the fixed rotation capacity limitation provided in DoD shows large discrepancy with the numerical results, a formula is proposed to predict the rotation capacity acceptance of flush endplate steel joint.