Seismic Improvement of Highway Bridges Using Base Isolation and Supplementary Damping by Steel Dowel Bars

Abstract

This research objective is to study the seismic behavior of bridge elements designed by isolated bridge system from earthquake excitation. Although choosing this system can reduce effect due to earthquake but at the same time, the superstructure causes greater displacement, posing the risk of pounding effect and collapse with unseating case. Therefore, in this research, improve the bridge with restrainer by using dowel bar. The study considers examples of the bridge from the standard bridge plan which comes from Department of highways (DOH). This bridge is prestressed concrete I-girder bridge with a span length of 20 m for 5 spans. There is install Elastomeric bearing as an isolated device and assumes this bridge establish at Chiang-Mai in Thailand. In addition, earthquake waves will be selected from Pacific Earthquake Engineering Research Center (PEER). The sets of ground motion have a magnitude of 5.7 to 6.5 and the distance from the source to the measuring station is less than 30 kilometers. After the bridge structure model was constructed, the structural analysis was performed by a dynamic method with Nonlinear response time history analysis (NLRHA) by using SAP2000 program. This analytical method is set up to compare the response between the original structure and retrofitting structure with restrainer by using dowel bar which such device will reduce the superstructure displacement and it can degrade energy that affects the response of bridge components.