Seismic Performance Analysis of Reinforced Concrete Frame Structures With Gap-SMA Isolation Bearings

In addition to protecting the superstructure, the isolation bearing should also be able to control the maximum displacement and the residual displacement of the isolation layer under earthquakes. Toward this end, this paper proposed an innovation type of lead rubber bearings (LRB) incorporating gap shape memory alloy (gap-SMA) bars, namely gap-SMA lead rubber bearings (gap-SMA LRB). First, the working principle of the gap-SMA LRB was briefly described, followed by physical tests on gap-SMA bearing specimens. Based on OpenSees, a case study focusing on a 5-story medical building was subsequently conducted, where two types of structure system, namely, fix-based system and gap-SMA LRB system were compared. Besides, the influence of the gap length on the shock absorption effect was analyzed. The results of elastic-plastic time history analysis show that such isolation bearing only has the lower stiffness provided by the rubber bearing during slight earthquakes, and the superstructure exhibits an ideal seismic response. With the increase of the ground vibration intensity, SMA takes effect, increases the horizontal stiffness of the bearing, and provides a certain self-centering ability, effectively reducing the residual deformation. This device possesses prominent self-centering and energy dissipation capacity.