半刚性可更换消能高强钢柱脚抗震性能试验研究

Experimental study on seismic performance of semi-rigid replaceable energy-dissipative high-strength steel column-base joint

在地震区应用高强钢结构的典型方案是“强柱弱梁”框架,即分别采用高强钢和普通钢形成强柱和弱梁。但地震作用下钢框架首层柱底受力大、易屈服,采用高强钢柱对结构抗震不利。为此,提出了一种半刚性可更换消能高强钢柱脚构造,设计并制作了2个足尺柱脚节点试件并对其分别进行2次低周往复加载试验,研究节点的消能能力与可恢复性能,并分析底板缺口形状、耗能板厚度对柱脚节点抗震性能的影响。试验结果表明:柱脚节点具备稳定的刚度,承载力与耗能能力随位移幅的增加而增加;在恒定轴压比0.23下,节点受弯承载力最大可达到柱截面屈服弯矩的57%,屈服后等效黏滞阻尼系数在0.10~0.22之间;底板采用梯形缺口可提高柱脚节点的刚度与耗能,但会降低其低周疲劳性能;耗能板的破坏模式均为缺口边缘疲劳裂缝开展;提高耗能板厚可以提高柱脚节点的抗震性能;除耗能板外,其余部件在试验中保持弹性,柱脚节点通过更换耗能板得到了快速修复,且修复后的柱脚节点仍具备稳定的承载力与耗能能力。

The typical way to employ high-strength steel structures in seismic zone is using the'strong-column-weak-beam'frame,namely,using high-strength steel and normal strength steel in columns and beams,respectively.However,the bottom section of the first-floor columns in a steel frame bears large loads and is thus easy to yield under an earthquake,which is unfavorable for the seismic performance of structures.Therefore,a novel semi-rigid replaceable energy-dissipative steel column-base joint was proposed in this paper,and two full-scale specimens were designed and prepared.Each of the two specimens was tested two times under low-cycle repetitive loads to investigate the energy-dissipative and recovery performance of the column-base joint,and further study was conducted to investigate the influence of the opening-shape and dissipative plate thickness on the seismic performance of the joint.The test results indicate that this column-base joint possessed rotation stiffness,and its load-resisting capacity and energy dissipation ability increase with the imposed displacement amplitude.Under a constant axial compression ratio of 0.23,the tested joints exhibit a maximum moment-resisting capacity of 57%of the yield moment of steel column.The post-yield equivalent viscous damping factor is in the range of 0.1 to 0.22.Using a trapezoidal-opening in the covering plate can improve the stiffness and energy dissipation capacity of the joint but reduces its low-cycle fatigue performance.The failure modes of all tested energy-dissipative plate are characterized by the crack propagating at opening edges.Increasing the energy-dissipative plate thickness can improve the seismic performance of the joint.Except for the energy-dissipative plate,the remaining components keep elastic during the test,and the performance of the damaged column-base joint was repaired by replacing the energy-dissipative plates.