NUMERICAL ANALYSIS ON ASEISMIC BEHAVIOR OF ECCENTRICALLY CONSTANT-COMPRESSED STEEL BOX COLUMN UNDER CYCLICALLY LATERAL LOADING

The mechanical performance of eccentrically constant-compressed steel box columns under cyclic lateral loading were analyzed by finite element models,in which the influence of material nonlinearity,geometric nonlinearity,initial geometric imperfection and residual stress were considered.The finite element models were proved to be accurate according to the comparison between results from the finite element analysis and experiments.Based on numerical results of 85 steel box columns,the aseismic 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 a web plate has dominant effect on the aseismic behavior of the columns.With the increase of the width-to-thickness ratio,the ductility of the column becomes weak,and the load-bearing capacity and stiffness of the column degenerate rapidly.When the axial compression ratio of middle slenderness ratio columns is small,the aseismic behaviors of columns are influenced by total instability,local buckling and plastic deformation,while the total instability is the dominated effect for the columns with a larger axial compression ratio.It is also found that the skeleton curve of the column has the performance of translational movement by the effect of bending moment at the loading joint of the column,while the effect of bending moment is relatively little and negligible.Based on the regressive numerical results,the bearing shear force at the loading joint and displacement ductility of eccentrically constant-compressed steel box columns under cyclic lateral loading are fitted.