EXPERIMENTAL TESTING OF A NEW HYSTERETIC DAMPER FOR BASE ISOLATED BRIDGES

摘要

An experimental procedure was developed to implement a simplified design method of supplemental dampers for isolated highway bridges. For seismically base-isolated bridges subjected to an earthquake, the principal modes of the structure are in the isolation level which effectively lessens the seismic base shear conveyed from the superstructure to the substructure. However, this also has the effect of increasing superstructure displacement. To control the deformation of the isolators, supplemental energy dissipating devices can be introduced into the isolation system. This may nevertheless increase the total structure base shear and the merit of adding dampers has to be evaluated properly. In this paper a new type of steel hysteretic damper is proposed and tested in combination with an elastomeric isolator using displacement controlled cyclic tests. This very simple and economic damper was designed using a simplified method presented in earlier works. First, having characterized the response of an elastomeric isolation bearing used in a real structure, a simple and economic hysteretic damper was designed in accordance with the simplified method. In the next step, the designed damper in parallel with an elastomeric isolation bearing was tested by a unidirectional displacement-controlled quasi static method. Results show that this new type of damper could be used in combination with isolators to control superstructure displacement and substructure base shear.