大空心率圆锥形中空夹层钢管混凝土压弯构件滞回性能研究

Study on hysteretic behavior of tapered concrete-filled double skin steel tubular beam-columns with large hollow ratio

为研究大空心率圆锥形中空夹层钢管混凝土压弯构件的滞回性能,对10个圆锥形中空夹层钢管混凝土压弯试件(8个往复加载和2个单调加载试件)进行试验研究。考察空心率(0.6和0.8)和轴压比(0、0.2、0.4和0.6)对试件的破坏模态、P-Δ关系曲线和滞回性能的影响,并建立数值模型对单调加载的压弯试件的受力机理进行分析,最后讨论了圆锥形中空夹层钢管混凝土压弯构件侧向承载力简化计算方法。研究结果表明,两种空心率试件的破坏形态基本一致,表现为试件下部不同程度的局部破坏;往复压弯试件的P-Δ曲线较为饱满,表现出较好的滞回性能。空心率从0.6增加到0.8对试件的侧向承载力和延性影响较小,两种空心率下的峰值荷载平均相差约3%。随着轴压比增加,试件的极限荷载降低,延性逐渐变差。往复加载试件的强度退化不明显,空心率为0.8的试件刚度退化更显著。试件的平均位移延性系数为3.56,平均黏滞阻尼系数为0.322,表现出较好的耗能能力。当空心率为从0.6增加到0.8,试件的黏滞阻尼系数平均提高15%。

To study the hysteretic behavior of tapered concrete-filled double skin steel tubular(CFDST) beam-columns with large hollow ratio, a total of ten tapered CFDST specimens, including eight cyclic loading specimens and two monotonic loading specimens, were tested.The influence of hollow ratio(0.6 and 0.8) and axial compression ratio(0, 0.2, 0.4 and 0.6) on the failure modes, the P-Δ relationship curves and hysteresis performance of specimens were investigated, respectively.A numerical model for the specimens under monotonic loading was also established to analyze the working mechanism of the beam-columns.Finally, the simplified calculation method for the lateral bearing capacity of tapered CFDST beam-columns was discussed.The test results show that the damage patterns of the specimens with different hollow ratio are basically same, and local damage with different extents was observed at the lower part of the specimens.The P-Δ curves of specimens under the cyclic loading are relatively full, showing a good seismic performance of tested specimens.The hollow ratio(0.6 and 0.8) has little effect on the lateral capacity and ductility, and the peak load of two specimens with different hollow ratio differs by about 3% on average.As the axial compression ratio increases, the ultimate load decreases and the ductility gradually deteriorates.The strength degradation of all cyclic loading specimens is slight, but a more significant stiffness degradation occurs for the specimen with a hollow ratio of 0.8.The average displacement ductility coefficient of the tested specimens is 3.56 while the average value of the viscous damping coefficient is 0.322, which shows that the CFDST specimens better energy dissipation behavior.When the hollow ratio incease from 0.6 to 0.8, the viscous damping coefficient of the specimens increases by 15% on average.