Dynamic analysis of three-directional vibration isolation and mitigation for long-span grid structure

Abstract

With the rapid development of the long-span space structures, some seismic isolation methods of ordinary buildings are also gradually applied in these structures. The special feature of the long-span space structure is that the vertical seismic property cannot be ignored, in addition to considering the horizontal property under multi-dimensional earthquake action. This study proposes a novel multi-dimensional earthquake isolation and mitigation device (MEIMD) consisted of viscoelastic core bearing and viscoelastic damper. This device provides certain stiffness that can satisfy the load-bearing capacity requirement of the structure and strong energy dissipation ability in the horizontal and vertical seismic directions. A mathematical model is presented to characterize the mechanical behavior of the MEIMD. The device is installed at the top of the support column, which creates a seismic isolation layer between the column and the upper grid model. The shaking table tests of the long-span grid structure with and without MEIMD under horizontal seismic excitations of various intensities were carried out. The experimental results showed that the acceleration response peak value on the isolation structure was significantly reduced. The novel device has a good horizontal isolation effect on the grid structure. To determine the vertical and three-direction seismic isolation properties of the MEIMD on the grid structure, finite element models of the long-span grid structure with MIEMD and without MEIMD were established for dynamic time history analysis. The numerical results revealed that the dynamic responses of the isolation grid in horizontal and vertical directions have been decreased compared to the non-isolated structure.