Research On Seismic Behavior Of Confined Hot-rolled H-Shaped Steel Columns

Steel columns have widespread applications in moment-resisting frames for their good seismic behavior. However, the steel columns are susceptible to damage caused by local and overall interaction buckling under constant axial load and cyclic lateral forces during earthquakes. Most of the researchers attempted to propose new width-thickness limit to solve the problems, however, it is difficult to avoid local buckling even for columns with small plate width-thickness ratio when subjecting to intense ground motion. Based on the concept of confined H-shaped steel members conceived by Xiao, this study investigates the seismic behavior of confined hot-rolled H-shaped steel columns. The concept aims at controlling the local buckling of the plates in the potential plastic hinge regions of an H-shaped steel column through applying additional confinement. A series of domestic Ma-gang hot-rolled H-shaped steel columns were tested and analyzed under constant axial load and cyclic lateral forces to validate the concept. The main work is summarized as follows:(1) A general overview of the application and research work on homemade hot-rolled H-shaped steel members is given; also a literature review of the experimental and analytical research work on seismic behavior of steel columns is presented.(2) Nine large-scale H-shaped steel model columns were designed to simulate typical columns in multi-story building in seismic regions. The nine model columns were divided into two groups, in which three were for weak axis bending and the others were for strong axis bending. There were two conventional model columns in each group without special confinement for providing benchmark date of seismic behavior of hot-rolled H-shaped steel columns.(3) All model columns were tested under constant axial load and cyclic lateral forces. The failure mode, strength degradation, stiffness degradation, ductility and energy dissipation were described in details to investigate the seismic behavior of the conventional and confined model columns. Compared with the conventional H-shaped steel model columns, the confined ones exhibited significantly improved seismic performance with large ductility.(4) The finite element analysis results indicate that the finite element model adopted in this study can effectively simulate the seismic behavior including loading capacity degradation and local buckling. The method can be used to design the local confinement and predict the seismic behavior of the confined columns proposed in this paper.