Experimental Study on Seismic Performance of Two Types of Rail‐Guided Isolation Bearings for Museum Artifacts

Retrofitting displayed artifacts in museums with seismic isolation technology serves as an effective means to enhance their safety levels during earthquakes. Two types of lightweight rail‐guided isolation bearings were proposed for small‐sized artifacts. The structural configurations and seismic isolation mechanisms of the bearing with constant stiffness using compression springs and that with variable stiffness using tension springs were presented. The equations of motion of the two bearings subjected to bidirectional horizontal seismic excitation were derived. Shaking table tests of five bearing models were conducted to evaluate their seismic performance, including three stiffness of compression springs and two stiffness of tension springs. Seven ground motion records scaled to different peak ground acceleration (PGA) levels and ten floor motion records with two horizontal components were used as the input. The effects of the input excitation, intensity level, spring stiffness, spring type on the seismic performance of the bearings were investigated according to the measured peak bearing accelerations and displacements (PBAs and PBDs) and the observed failure cases of the vase freestanding on the bearing. The experimental results showed that three bearing models with proper stiffness of compression or tension springs can withstand rare earthquakes with no rocking of the vase freestanding on the bearing. Two bearings fail to work due to large PBAs rocking the vase, which are caused by reaching the displacement capacity or the low isolation efficiency of the bearing at high PGA levels. With the increase of the PGA, the PBAs and PBDs increase. With the increase of the spring stiffness, the PBA increases, while it is not true for the PBD. Finally, the addition of brush dampers enables the bearings to meet higher performance targets.