反复水平荷载作用下偏心常轴压箱形钢柱抗震性能的数值分析

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

建立考虑材料非线性、几何非线性、几何初始缺陷、残余应力影响的有限元模型,对反复水平荷载作用下偏心常轴压箱形钢柱的受力性能进行模拟分析。通过与相关试验结果的比较,验证了有限元模型的正确性。在此基础上,对85个箱形构件进行数值分析,研究反复水平荷载作用下常偏压箱形钢柱的抗震性能。研究结果表明,腹板宽厚比是影响构件抗震性能的最主要因素,腹板宽厚比越大,构件的刚度、承载力退化越严重,延性越差。对于中等长细比的构件,当轴压比较小时,构件的抗震性能受整体失稳、局部屈曲和塑性变形的相互影响;但当轴压比较大时,整体失稳将起控制作用。柱顶弯矩使构件的骨架曲线发生平移,但柱顶弯矩对构件抗震性能的影响相对较小。根据有限元计算结果,回归出反复荷载作用下偏心常轴压箱形钢柱可承受的最大柱顶剪力和位移延性系数的拟合公式。

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 ratiocolumns 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.