FINITE ELEMENT ANALYSIS ON THE INFLUENCE OF STEEL STRENGTHEN THE SEISMIC BEHAVIOR OF STEEL COLUMN

High strength steel has been applied in many steel structures all over the world, but the width-to-thickness ratio limits of steel columns in seismic design codes of many countries are not completely applicable to high strength steel columns lacking of sufficient research. In order to study the influence of steel strength on the seismic behaviour of steel columns, finite element analysis is conducted to analyze the hysteretic behavior of steel box columns under a constant compressive axial force and cyclic lateral loading. The finite element model is built by the shell element and a multilinear kinematic hardening material model is employed. 3 kinds of steel grades, i.e. Q235, Q460 and Q690, are selected to carry out the analysis. The influences of the yield ratio, ultimate strain and the yield plateau length are investigated based on the analysis results. Then suggestions for the width-to-thickness ratio limits of high strength steel columns under severe earthquakes are proposed.