Experimental and numerical study on cyclic behavior of eccentrically-compressed steel box columns

Abstract

In order to investigate the seismic behavior and relevant buckling mechanisms of eccentrically compressed steel box columns, quasi-static tests on 16 eccentrically compressed steel box columns and numerical simulations on 92 computational columns were conducted. The effects of various parameters, including the width–thickness ratio of web plate, cross-sectional height–width ratio, slenderness ratio, axial compression ratio, and bending moment of the top of column, were investigated. The results indicated that the width–thickness ratio of web plate was the most significant factor of the seismic behavior and the buckling performance of the column specimens; that is, greater web width–thickness ratios were associated with smaller areas enclosed by the hysteresis loop, more severe degradations of the load carrying capacity and rigidity of the column, and a lower buckling load and failure load of the specimen. In addition, when the axial compression ratio was less than or equal to 0.1, the influence of axial force on the seismic behavior of the column was negligible; in contrast, when the axial compression ratio was greater than 0.1, the influence of axial force on the seismic behavior of the column was significant and worthy of consideration. In general, the width–thickness ratio of web plate, axial compression ratio, and slenderness ratio affected the seismic behavior and buckling performance of the column specimens significantly, while the influence of the cross-sectional height–width ratio and bending moment of the top of the column were relatively smaller. The results also revealed that the instability features of steel box columns under cyclic loading can be categorized into three types, in which the local buckling governs, the local buckling and the global instability interact, and the global instability governs. Based on experimental and numerical studies, formulas were established to calculate the stability bearing capacity and maximum deformation of the top of steel box columns under cyclic loading in order to improve their seismic design.