Evaluation of Applicability of Seismic Base Isolation for Bridges According to Vietnamese Codes

Abstract

Seismic base isolation (SBI) has been increasingly used to enhance the seismic performance of important structures. However, this technique was primarily developed for constructions located in high seismic areas and it is still rarely adopted as common isolation systems in moderate seismic areas. This paper attempts to investigate the seismic performance of SBI and its applicability for bridges located in moderate seismic regions such as Vietnam. The bilinear model is used for addressing the seismic behaviour of isolators. Seismically isolated-bridge analyses are conducted essentially based on the nonlinear time history analysis method (NLTHA). A parametric study is conducted on equivalent simplified models, subjected to ground motions according to the Vietnamese code (TCVN 9386–2012), to investigate the seismic responses of isolated-bridges and the SBIs efficiencies. The applicability of SBI for bridges in such regions is drawn on the evaluation of appropriate seismic responses in force, displacement, and residual displacement. The obtained results indicate that SBIs with moderate characteristic strength (Q_d) and high post-elastic stiffness (K_d) show the best performance for bridges in such seismic regions.