双向地震作用下U形钢阻尼器力学性能研究

Mechanical properties of U-shaped steel damper subjected to bi-axial ground motions

U形钢阻尼器与橡胶隔震垫安装在隔震层中能够有效减小上部结构地震响应。隔震层在多维地震作用下可产生双向变形,导致安装在隔震层中的U形钢阻尼器能同时承受纵向与横向的变形。为了研究U形钢阻尼器在同时承受双向变形时的力学性能,设计了5个试件,并进行了拟静力试验。试验加载沿实验体斜向45°方向进行。试验结果表明,阻尼器的长度及宽度对于其承受双向变形时的性能有较大影响,在循环荷载作用下耗能钢板表现出显著的几何非线性工作性质,产生不可恢复的平面外变形,在一定程度上导致其承载力下降。基于试验结果建立并校核了有限元分析模型,对阻尼器的几何参数进行了优化,有效控制了阻尼器的平面外变形,使其在工作过程中可以保持稳定的承载力。

U-shaped steel dampers and rubber bearing are installed on the isolation layer to reduce the seismic response of the upper structure. During the earthquake,the isolation layer may have biaxial deformation,thus the U-shaped steel dampers installed on the isolation layer also need to sustain the biaxial deformation. In order to explore the mechanical properties of the U-shaped steel damper under biaxial deformation,five specimens were tested along 45 degree direction. The test results suggest that: the thickness of the energy dissipation plates and the length of the damper have a great influence on its performance; under the cyclic load,the energy dissipation plates will have out-ofplane distortion,leading to a reduction of the damper strength. Finite element models were established to simulate the performance of the damper. Base on the test and analysis results,the damper was optimized to reduce the out-of-plane distortion and keep stable bearing capacity.