Experimental investigation on cyclic behavior of Q690D high strength steel H-section beam-columns about strong axis

Abstract

Q690 high strength steel (HSS) is a structural steel with yield-to-tensile ratio being generally greater than 0.90 and elongation lower than 20%, resulting in considerable decrease in steel member ductility. In seismic affecting zones, steel members are usually designed as compact sections to avoid premature local buckling for attaining fully developed plasticity. However, this approach increases the potential risk of fracture for Q690 steel structures. Thus, cyclic behaviors of Q690D HSS compact section beam-columns need to be thoroughly investigated. To this end, this paper conducted five cyclic loading tests of Q690 HSS compact H-section beam-columns based on a reliable testing system. The influences of the flange width-to-thickness ratio, web height-to-thickness ratio, axial-load ratio and overall slenderness on the failure mode, energy dissipation capacity and hysteretic behavior were analyzed. It shows that plastic local buckling dominates the failure mechanism of all the specimens without overall buckling being observed. The ultimate inter-story drift ratio was more than 1/50. The Q690 welded beam-columns with Class 1 and Class 2 H-section exhibit not only favorable plastic deformability but also excellent energy dissipation capacity and therefore could be applied in seismic steel frames. To attain accurate evaluation of damage and cyclic response, two damage models and two point-oriented hysteretic models were selected and combined to form four damage-based hysteretic models. The four hysteretic models were then implemented to simulate the cyclic loading experiments. It was found that the ultimate strength-oriented hysteretic model incorporated with Kumar Satish damage model provides the most accurate simulation. The hysteretic model parameters were calibrated using experiments data. The simulation results of the developed hysteretic model match well with those experimental curves.