装配U形阻尼器的SMA自复位钢框架梁柱节点抗震性能研究

Seismic behavior of SMA self-centering steel beam-to-column connections with U-shaped dampers

为解决传统SMA螺杆自复位钢框架梁柱节点在工作过程中SMA材料利用率低的问题,简化节点耗能构件的设计、施工和震后更换,提高灾后结构的快速恢复能力,提出了由超弹性SMA螺杆贯穿钢柱翼缘连接且装配U形阻尼器的自复位钢框架梁柱节点,并对关键构件的受力性能进行分析,给出节点的受力变形理论模型。通过循环拉伸试验考察了SMA棒材的超弹性特性,以此为基础,设计了1个足尺边柱节点试件,通过拟静力试验研究其承载力、初始转动刚度、残余变形、滞回耗能等。研究结果表明:节点中SMA螺杆可以有效拉伸变形并提供自复位驱动力,U形阻尼器的两肢能够产生相对位移从而进行塑性耗能,钢梁腹板处的抗剪螺栓可在连接槽钢的长圆孔中滑动,梁柱节点核心区未出现剪切变形;在设计层间位移角为0.04 rad的循环结束时,节点残余变形仅为0.0049 rad,且梁柱构件在试验过程中未出现屈服,节点具有良好的自复位能力和可修复性;节点的初始转动刚度和极限弯矩均小于普通抗弯钢框架梁柱节点,但其拥有良好的转动能力,最大层间位移角为0.05 rad,满足节点的变形设计要求。

To solve the problem of low SMA material utilization of traditional self-centering steel beam-to-column connections with SMA bars during the working phase,a kind of self-centering steel beam-to-column connection was proposed,which was equipped with U-shaped dampers and superelastic SMA bars connected through steel column flanges.The proposed connection can simplify the process of design,construction and replacement of energy-consuming components,and accelerate the post-earthquake structural recovery.In this research,the mechanical properties of the connection and the critical components were analyzed and the force deformation theoretical model was proposed.The superelastic properties of SMA bars were investigated by cyclic tensile test.On this basis,a full-size side-column connection specimen was designed,and its bearing capacity,initial rotational stiffness,residual deformation and hysteretic energy dissipation were studied through a pseudo-static test.The results show that the SMA bars in the connection can effectively stretch,and provide self-centering driving force.The two limbs of the U-shaped dampers can generate relative deformation and thus enable plastic energy dissipation.The shear bolts at the beam web can slide in the long hole of the steel bracket,and there is no shear deformation in the core area of the beam-to-column connection.The residual inter-story ratio of the specimen is only 0.0049 rad at the end of the cycle with a designed inter-story ratio of 0.04 rad,and the beam and column are always in the elastic stage without damage during the test,which reflects a good self-centering ability and repairability.The initial rotational stiffness and ultimate bending moment of the specimen are both smaller than those of steel moment-resisting beam-to-column connections.Moreover,the maximum inter-story ratio of the specimen is 0.05 rad,which meets the deformation design requirements.