Isolation effectiveness of lead rubber bearing on low-medium-speed maglev vehicle-bridge system under earthquake

The constructed maglev line generally extends for dozens of kilometers or even hundreds and thus inevitably passes across earthquake-prone regions, which exposes the viaducts to the potential risk of seismic damage. The leader rubber bearing (LRB), a commonly employed isolation support in highway and railway bridges to mitigate seismic responses, is expected to be applied into maglev line for seismic protection. However, research in this domain remains relatively scarce. This paper digs into the isolation effectiveness of LRB on low-medium-speed maglev vehicle-guideway system under earthquake. An analysis model for seismic responses of the maglev vehicle-guideway system incorporating LRB was formulated, where the maglev vehicle was simplified as a multi-rigid-body dynamic model with 50 degrees of freedom and accounted for actively-controlled electromagnetic forces. The fast nonlinear analysis technique was introduced to solve such complicated nonlinear system. Then, the seismic isolation effectiveness of LRB on the vehicle-guideway system was thoroughly investigated, and a parametric study was conducted to identify the critical factors such as pier heights and LRB dimensions that influence the isolation effectiveness. Additionally, the driving quality of vehicle moving on LRB-isolated bridge was studied to evaluate the applicability of LRB to maglev line bridge. It reveals that, the installation of LRB effectively reduces the seismic responses of bridge but enlarges the vehicle responses under earthquake. Factors including pier height, LRB initial elastic stiffness and yield force exhibit significant influence on the seismic-reduction rate for the coupling system. It is recommended that the isolation degree of LRB should not exceed 2.50 during the design of LRB-isolated bridge, thereby achieving a balance between seismic isolation effectiveness of LRBs and vehicle driving quality.