Seismic protection of reinforced concrete continuous girder bridges with inerter-based vibration absorbers

Reinforced concrete (RC) continuous girder bridges located in earthquake-prone areas are susceptible to large vibrations under seismic excitation, which may lead to the damage of the connection between the girder and pier. The present study proposes a multi viscous inerter dampers (MVIDs) system installed between the girder and piers to control the transverse seismic vibrations of RC continuous girder bridges. The governing equations of the MVIDs-controlled continuous girder bridge under earthquake excitation are first formulated. Then, a nu-merical case study of an RC continuous girder bridge with five piers equipped with MVIDs is analyzed to demonstrate its vibration mitigation performance. Design parameters of MVIDs are optimized using multi -objective genetic algorithm aimed at minimizing the relative displacement between pier caps and girder. For comparative purposes, the mitigation effects of a traditional multi viscous dampers (MVDs) system are also discussed to highlight the advantages of MVIDs. It is found that the MVIDs can achieve mean reduction ratios of 82.3%, 75.7%, and 76.2% in the peak transverse relative displacements of the nodes where the MVIDs are installed. The maximum reduction ratios of the mean maximum displacement and acceleration responses are 70.7% and 41.1%, respectively. In general, MVIDs have a better seismic control effect than MVDs. Robustness analysis of the optimally designed MVIDs is also performed under perturbation to the lateral stiffness of rubber bearings and damping ratios of viscous dampers. The analysis of robustness indicates that control effects of MVIDs are more sensitive to the damping ratio than the lateral stiffness of rubber bearing.