Seismic Protection Of Bridges Using Viscous Dampers
Free (open access)
M. Spizzuoco, G. Serino & C. Onorii
The proposed paper deals with the seismic protection of bridges by means of passive energy dissipation viscous devices installed between the continuous beam deck and the supporting piers. An analytical approach is used to study the problem and a simple design procedure, using the frequency response analysis, is provided to determine the optimal value of the viscous damping parameter characterizing the dampers. Finally, the adequacy of the procedure is verified through time history analyses on an existing bridge. Keywords: bridges, retrofit of bridges, viscous devices, passive control. 1 Introduction The most recent bridges’ seismic design procedures, which are essentially related to the concepts of performance-based and damage-controlled design, have made clear that the only increase of the design force levels does not improve the earthquake bridge performance. The preferential innovative strategy for controlling excessive vibrations induced by earthquake loads in new bridge structures (design perspective) as well as in existing ones (retrofit perspective), is the use of supplemental energy dissipation systems. They generally require a relative movement in the structure to activate the dissipation devices. The aim of incorporating supplemental damping devices in the design or retrofit of a bridge structure is the reduction of the dynamic response amplification. This is obtained by increasing the structural equivalent viscous damping according to the response spectra of the earthquake record at the site. In fact, the addition of a supplemental damping to a structure is more beneficial if the fundamental period of the construction including the damping devices falls within the range where
bridges, retrofit of bridges, viscous devices, passive control.