反复水平荷载作用下偏心常轴压箱形钢柱抗震性能试验研究

通过4组16根箱形钢柱在偏心常轴压、柱顶反复水平荷载作用下的拟静力试验,研究轴压比、腹板宽厚比、柱顶弯矩等因素对箱形柱滞回性能的影响.试验表明,当柱顶轴力在腹板平面外的偏心小于b/8(b为翼缘板宽度)时,试件壁板屈曲变形为一个半波,腹板外凸,翼缘板内凹,变形基本对称.试件的塑性变形主要集中在柱根部区域,最大塑性变形一般出现在距固定端0.4～0.5h(h为腹板宽度)处.腹板宽厚比是影响构件抗震性能的主要因素,宽厚比越大,滞回曲线越不饱满,骨架曲线下降越陡,承载力及刚度退化越严重;轴压比的影响次之;柱顶弯矩的影响较小.根据试验结果,提出构件适用于四类抗震等级的定量判定标准及大跨度钢结构中箱形钢柱腹板宽厚比的设计建议.

Experimental study on seismic behavior of eccentrically constant-compressed steel box column under cyclically lateral loading

Pseudo-static experiments on seismic behavior of 16 eccentrically constant-compressed steel box columns under cyclic lateral loading are conducted.The effects of axial compression ratio,width-to-thickness ratio of web plate and bending moment on the seismic behavior of steel box columns are investigated.The experimental results show that the buckling mode of box web plates is influenced by the loading eccentricity of axial compression outside the web plane.If the eccentricity is less than b/8(b is the flange width),the buckling mode of the box web plates is deformed as a half sine-wave,in which the web plates deform outwards from the box and the flanges inwards,and the buckling deformation is almost symmetrical.The plastic deformation of the columns under cyclic load occurs mainly in the fixed end of specimen,and the greatest plastic deformation is generally found at 0.4h or 0.5h away from the fixed end,where h is the width of the web plate.It is also found from the experiments that the width-to-thickness ratio of web plate has the most significant effect on the seismic behavior of the steel box columns.The larger the width-to-thickness ratio is,the less plumpy the hysteresis curve becomes,the faster the skeleton curve declines,and the more severely the load-bearing capacity and stiffness of the column degenerates.The axial compression ratio has more significant effect on the seismic behavior of columns,while the effect of bending moment at the loading joint of the column is little and negligible.Based on the experimental results,a practical criterion to evaluate the applicable seismic grade of steel members and some design suggestions of width-to-thickness ratio of box-section steel column in large span structures are proposed.