Mechanical behavior and seismic design suggestions of steel box column

Based on quasi-static experimental results of steel box columns and numerical results of calculated members,the effects of width-to-thickness ratio of web plate,slenderness ratio,axial compression ratio and bending moment on the seismic behavior of eccentrically constant-compressed steel box columns under cyclic lateral loading were investigated.The study results show that the width-to-thickness ratio of web plate and the slenderness ratio have very significant effect on the seismic behavior of columns.When the width-to-thickness ratio of web plate or the slenderness ratio of the column increases,the ductility and load-bearing capacity of the column decrease rapidly,which indicates the seismic resistance of the column is deteriorated.The ductility of the column on one side is improved by the effect of bending moment at the loading joint of the column,while the ductility of the column on the other side is decreased.The effects of bending moment on the seismic behavior of the columns are relatively small.Based on the experimental and numerical results,the limits of width-to-thickness ratio and slenderness ratio of steel box columns in large span structures were proposed,which were dependent on the stress state of the columns.The concept of member displacement angle was introduced,and the method to determine seismic grade of steel members was also developed.Finally,the seismic design procedure of width-to-thickness ratio and slenderness ratio of steel box columns was suggested.