Seismic performance upgrade of highway bridges using a novel hybrid placement of bonded and unbonded laminated rubber bearings

To enhance the seismic performance of highway bridges supported by laminated rubber bearings, this study proposes a novel hybrid placement of bonded and unbonded bearings. The typical analytical models of the hybrid bearing system are obtained and its critical design parameters are identified through theoretical analysis. A design procedure is then established to rapidly determine the design parameters for the hybrid bearing system according to specified design objectives. Nonlinear time history analyses are conducted to demonstrate the impact of the hybrid bearing system on the seismic responses of bridges. The analytical results indicate that the hybrid bearing system, when designed using the proposed procedure, can achieve the desired hysteretic behavior. The hybrid system combines the benefits of both bonded and unbonded bearings, effectively controlling maximum and residual bearing displacements without significantly increasing the seismic demand on bridge piers. The design parameters for the hybrid bearing system should be determined by carefully balancing the responses between the bearings and the piers.