Energy dissipating restrainers for highway bridges

Recent destructive earthquakes have demonstrated the vulnerability of highw ay bridges to collapse due to excessive movement beyond the available seat widths at expansion joints. This paper investigates the efficacy of using e nergy dissipating restrainers at expansion joints for preventing collapse o f highway bridges in the event of a severe earthquake. The restrainer consi sts of a nonlinear viscous damper and an elastic spring connected in parall el or in series. Two-dimensional finite element analysis using bilinear hys teretic models for bridge substructure joints and nonlinear gap elements fo r expansion joints is performed on example bridges with one or two expansio n joints. The analytical study demonstrates that the energy dissipating res trainers are effective in reducing the relative opening displacements and i mpact forces due to pounding at the expansion joints, without significantly increasing ductility demands in the bridge substructures. (C) 2000 Elsevie r Science Ltd. All rights reserved.