Seismic Design of Bridges against Near-Fault Ground Motions Using Combined Seismic Isolation and Restraining Systems of LRBs and CDRs

Abstract EN

This paper focuses on the seismic isolation design of near-fault bridges under the seismic excitations of near-fault ground motions in high-intensity earthquake zones and proposes a combined control system using lead rubber bearings (LRBs) and cable displacement restrainers (CDRs) along with ductility seismic resistance for the reinforced concrete piers.

As part of the performance-based seismic design framework, this study provides the quantitative design criteria for multilevel performance-based objectives of a combined control system under conditions of frequent earthquake (E1), design earthquake (medium earthquake), and rare earthquake (E2).

Moreover, in this study, a preliminary performance-based seismic isolation design for a near-fault actual highway bridge in high-intensity earthquake zones (basic peak of ground acceleration 0.4 g) was developed.

Using nonlinear time-history analysis of the actual bridge under near-fault ground motions, the feasibility of a performance-based design method was validated.

Furthermore, to ensure the predicted performance of the isolated bridges during a strong earthquake, a relatively quantitative design in structural details derived from the stirrup ratio of piers, expansion joints gap, supported length of capping beams, and limited vertical displacement response was obtained.