Experimental investigation and modeling of cyclic behavior of high strength steel

Abstract

With the increase in mechanical strength, the yield to tensile strength ratio becomes more close to 1 and the elongation ratio appears a significant decrease, indicating a deterioration in the ductility and seismic behavior of high strength steel (HSS). For seismic design, understanding of the ductility and cyclic behavior in material level is important to guarantee the abilities of structural steel members to endure expected inelastic deformation under severe earthquake actions. This paper presents an experimental evaluation on the uniaxial cyclic behavior of Q460C steel through 6 cyclic loading tests. The specimens were cut and machined from both steel plates and flanges of hot-rolled H-shaped steel with the nominal yield strength of 460MPa. For the purpose of comparing to normal strength steel, additional cyclic loading test was conducted on Q345B steel. Full hysteretic loops were achieved for HSS as well as normal strength steel. Based on the observations of the test results, a simple piece-wise model was developed for predicting the cyclic behavior of high strength steel, with considering the observed Bauschinger effect and cyclic strain hardening. To verify the accuracy of the proposed hysteretic model for HSS, quasi-static cyclic loading tests of Q460C steel beam-columns were simulated. The comparison between the experimental and predicted moment–curvature curves showed a good agreement, indicating a reasonable efficiency of the proposed trilinear kinematic hardening model in predicting the hysteretic behavior of HSS beam-columns.