Numerical investigation on cyclic behavior of Q690 high strength steel beam-columns

Abstract

It has been well-recognized that high strength steels possess worse ductility and deformability compared to normal strength steels, leading to greater risk of low-cycle failure. In addition, high strength steels generally exhibit prominent cyclic softening behavior rather than cyclic hardening behavior. These characteristics should be properly implemented into finite element model to gain exclusive numerical simulation on cyclic behavior of high strength steel beam columns. In this paper, finite element models which not only consider the initial imperfection but also incorporate the ductile fracture behavior as well as cyclic softening behavior were established and used to simulate cyclic loading experiments on high strength steel beam-columns bending about strong axis. The simulation results including hysteretic curves and failure modes both provide good agreement with experimental results, verifying the capability of finite element models proposed. Accordingly, a parametric study was conducted to investigate the effects of axial load ratio, flange width-to-thickness ratio and web height-to-thickness ratio on cyclic behaviors of Q690 high strength steel beam-columns. It can be concluded that the increase in flange width-to-thickness ratio and axial load ratio will change the damage mechanism and consequently present different cyclic deterioration characteristics. Furthermore, the increase in flange and web slenderness and axial load ratio results in decrease in deformability and sectional plasticity development ability.