壁式钢管混凝土柱抗震性能试验研究

通过3个截面高宽比为3.0的壁式钢管混凝土柱足尺试件在高轴压比下的低周反复加载试验和有限元分析，研究壁式钢管混凝土柱的破坏模式、滞回行为、承载能力、变形性能和能量耗散能力。结果表明：试件的破坏模式为压弯破坏，破坏区域钢板受压鼓曲、钢管纵向焊缝涨裂、混凝土压溃；试件滞回曲线稳定饱满，无明显捏拢现象；纵向隔板能够约束钢管壁板平面外变形，提高钢板局部屈曲强度；试件破坏时位移延性系数大于3.0，等效黏滞阻尼系数大于0.4，减小钢管壁板宽厚比可有效增加试件耗能能力。设计轴压比为0.54～0.69时，壁式钢管混凝土柱屈服位移角大于0.005rad，极限位移角大于0.02rad，具有良好的变形性能和耗能能力。建立的精细有限元模型可准确预测壁式钢管混凝土柱在恒定轴力和反复水平力下的滞回行为。有限元分析表明，轴压比对壁式钢管混凝土柱的极限位移影响显著，提高含钢率可有效增加其承载力和变形性能。

Experimental study on seismic behavior of walled concrete-filled steel tubular columns

To study the failure mode, hysteretic behavior，load-carrying capacity, deformability and energy dissipation capacity of walled concrete-filled steel tubular (WCFT) columns, the pseudo-static experiments and finite element analysis were conducted on three full-scale specimens with a depth-to-width ratio of 3.0 under a high axial compression ratio. The results show that the specimens fail in axial-flexural mode, which is characterized by local buckling of steel plates, fracture of longitudinal welds of steel tube and crushing of concrete. The specimens are able to realize stable hysteretic cycles without significant pinching effects. The longitudinal partition can restrain the out-of-plane deformation of the tubular walls effectively, thus increasing the local buckling strength. Upon failure of the specimens, the displacement ductility factors are above 3.0 and the equivalent viscous damping coefficients are above 0.4 for all the specimens. Reducing the width-to-thickness ratios of the tubular walls can effectively increase the energy dissipation capacity of the specimens. When the design axial compression ratios vary from 0.54 to 0.69, the yield drift ratios of the specimens are more than 0.005 rad and the ultimate drift ratios are more than 0.02 rad, showing excellent deformability and energy dissipation capacity. Furthermore, the proposed finite element model can accurately predict the hysteretic behavior of the WCFT columns subjected to a combination of constant axial load and cyclic lateral load. The analysis shows that the axial compression ratios have a great influence on the ultimate displacement. Increasing the steel ratios can effectively improve the load-carrying capacity and the deformability.