Viscoelastic Dampers at Expansion Joints for Seismic Protection of Bridges

This paper presents the result of a study on the use of viscoelastic dampers at expansion joints of highway bridges for preventing superstructure decks from falling off the seats and/or from colliding with each other in the event of a severe earthquake. The Kelvin and Maxell models, consisting of an elastic spring and a linear viscous damper combined in parallel and in series, respectively, are considered for analysis. A 2D finite-element analysis using bilinear hysteretic models for bridge substructures joints was performed on example bridges constructed with one or two expansion joints. It was demonstrated that the damper is effective in suppressing the relative displacements at the expansion joints without introducing a significant increase in ductility demands for the substructures. The result also showed that the spring component of the Kelvin and Maxwell models has little effect on the performance of the damper component. This study clearly indicated that the use of linear viscous dampers offers a practical solution to the seismic problem that often arises from bridges with expansion joints.