Optimum design and performance evaluation of inerter‐based dampers for seismic protection of adjacent bridges

Pounding between adjacent bridge structures was frequently observed in previous major seismic events. This paper proposes using inerter-based dampers (IBDs) to preclude pounding damage between adjacent bridges, and comprehensively investigates their optimum designs and control performances. Specifically, four classical IBDs are investigated, including tuned inerter damper (TID), tuned mass damper inerter (TMDI), tuned viscous mass damper (TVMD), and spring dashpot inerter system (SDIS). Analytical models of adjacent bridges equipped with these IBDs are developed, and corresponding equations of motion are derived. Three control objectives are defined, and the numerical search method is utilized to determine the optimum design parameters of IBDs for each control objective. In addition, sensitivity analysis is performed to demonstrate the robustness of IBDs against the uncertainties from their actual design parameters. Finally, the control effectiveness of IBDs under various excitations, including the white noise and natural seismic events, are investigated and compared with each other. The results show that the introduction of IBDs could reduce not only the relative displacement between the adjacent bridges but also the displacement and acceleration responses of each individual bridge; the TVMD and SDIS are more effective than the TID and TMDI with the same inertance, but the TID and TMDI can achieve optimal performance with smaller damping ratio. In addition, the control forces of the optimal TID and TMDI are smaller than those of the TVMD and SDIS with the same inertance ratio.