Comparative Analysis Between the Bridge Standards of USA, EU, Canada, and Vietnam in the Preliminary Design of Seismic Base Isolation

Seismic Base Isolation (SBI) was considered an effective solution in earthquake-resistant design and is increasingly being used to enhance the seismic performance of critical infrastructures, especially bridge structures. The SBI is designed to prolong the fundamental vibration period and improve the energy dissipation capacity of structures, resulting in a reduction of seismic impacts on the bridge. Thus, seismic properties, notably those of spectral acceleration, have a strong impact on the SBI design criteria. In Vietnam, the seismic load is currently determined according to two different design standards, which are developed separately based on the Eurocode and American standards. Accordingly, the spectral shape determined by such methods is considerably different, especially over long periods, which is the range of interest for the SBI technique. Therefore, the seismic performance and the potential application of SBI are evaluated in different manners. This paper aims to investigate the effects of such different methods on the seismic responses of isolated bridge structures. A comparative study of the current Vietnamese seismic design standards was carried out to critically evaluate their effects on the seismic performance of SBI applications in seismic regions of Vietnam. The obtained results show that the seismic calculation according to TCVN 11823:2017 is significantly different from the standards of the US, EU, and TCVN 9386:2012. Updating and synchronizing seismic calculations in the Vietnamese standard system is critically necessary.