Seismic Isolation Performance and Influence Rule Analysis of Large-Span Steel Truss Isolated Structures
Due to the prominent vertical vibration of large-span spatial structures,it is difficult for horizontal isolation bearings to reduce the vertical seismic response of the structure effectively.In this paper,the friction pendulum system(FPS)horizontal isolation bearing and the air spring-FPS three-dimensional isolation bearing were applied to a large-span steel truss,and the isolation control effects of the horizontal isolated structure and three-dimensional isolated structure under different ground motions were analyzed.The results show that both horizontal and three-dimensional isolation bearings can significantly prolong the natural vibration period of the structure,and the first vibration mode is the horizontal translation of the upper truss structure.The dynamic time-history analysis indicates that under ordinary ground motion,near-fault pulse-type ground motion,and far-field long-period ground motion,the average isolation rates of horizontal isolation bearing to the horizontal and vertical nodal peak acceleration of the truss are 43.4%and 9.2%respectively,and the average isolation rates of three-dimensional isolation bearing to the horizontal and vertical nodal peak acceleration of the truss are 43.8%and 24.4%,respectively.The average isolation rates of the horizontal and three-dimensional isolation bearing to the member peak von Mises stress of the truss are 4.2%and 17.7%,respectively.The horizontal and three-dimensional isolation bearing has the same control effect on the horizontal seismic response of the truss,and the three-dimensional isolation bearing has a better control effect on the vertical seismic response of the structure.