圆端形不锈钢管混凝土桥墩抗震性能试验研究

以外钢管材质、加载方向及中空夹层截面为变化参数，进行了 4个圆端形不锈钢管（concrete-filled round-ended stainless steel tubular，CFRST）和2个圆端形普通钢（concretefilled round-ended carbon steel tubular，CFRT）混凝土桥墩试件的往复加载拟静力试验. 分析了试件的破坏形态、滞回性能、骨架曲线、延性系数及耗能等. 试验结果表明：圆端形不锈钢管混凝土桥墩试件的破坏形态均为墩底外钢管的鼓曲及底部混凝土的局部压溃，各试件的滞回曲线较为饱满，无明显捏拢现象，耗能能力及延性均较好；与圆端形钢管混凝土桥墩试件相比，圆端形不锈钢管混凝土桥墩试件的峰值荷载及初始刚度基本不变，但延性及耗能能力增加，刚度退化程度减小；与圆端形实心不锈钢管混凝土桥墩试件相比，圆端形中空夹层不锈钢管混凝土桥墩试件沿强轴加载时峰值荷载、初始刚度、延性及耗能能力均增加，而沿弱轴加载时由于内钢管平直段发生向内凹曲，其峰值荷载及初始刚度虽仍有增加，但延性及耗能能力略有降低. 给出了此类桥墩水平承载力的计算方法，计算结果与拟静力试验结果吻合较好.

Experimental Study on Seismic Behavior of Round-ended Concrete-filled Stainless Steel Tubular Bridge Piers

Cyclic quasi-static tests were carried out on four concrete-filled round-ended stainless steel tubular(CFRST) bridge pier specimens and two concrete-filled round-ended carbon steel tubular (CFRT) bridge pier specimens with different steel tube materials, loading directions and hollow sections. The failure patterns, hysteretic behavior, skeleton curves, ductility ratio and energy dissipation of these specimens were analyzed. The experimental results show that the failure mode of CFRST specimens is the buckling of bottom tubes as well as the crushing of bottom concrete. The hysteretic loops are plump, there are no obvious pinching of curves and the energy dissipation capacity and ductility are good. Compared with round-ended steel tubular bridge pier specimens, the bearing capacity and initial stiffness are almost the same as those of CFRST specimens, the ductility and energy dissipation capacity of CFRST specimens are increased, and the stiffness degradation is decreased. Compared with CFRST specimens with a solid section, the horizontal bearing capacity, initial stiffness, ductility and energy dissipation capacity of CFRST specimens with a hollow section are increased when loading along the strong axis. When loading along the weak axis, the bearing capacity and initial stiffness of CFRST specimens with a hollow section are still higher than those of the specimens with a solid section. But the ductility and energy dissipation capacity of CFRST specimens with a hollow section are slightly lower than those of the specimens with a solid section due to the buckling of the flat portion of steel tubes near the base. A calculation method of the horizontal bearing capacity of the piers is given, and the calculation results are in good agreement with the quasi-static test result.