The current seismic code for bridges in the Philippines adopts concepts from the American Association of State Highway and Transportation Officials’ (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications, 2012. It utilizes the Force-Based Design (FBD) approach, which has been applied in bridge seismic design since the 1990 Luzon Earthquake. However, AASHTO recently recommends the use of Displacement-Based Design (DBD) as an alternative approach in defining seismic performance levels. The study attempts to adopt the concept from DBD to investigate the effects of seismic isolation together with soil-structure interaction (SSI) towards typical bridge structures in the Philippines. The approach for evaluating the structure’s limit state and seismic performance was conducted following the provisions of the Japan Road Association Specifications for Highway Bridges (JRASHB), 2012. The application of isolation bearings on structures with distinctive natural periods was evaluated based on its effectivity and applicability. The earthquake response analysis was also performed to analyze its influence on the structure to develop a more accurate representation of its seismic response. Furthermore, the effects of the individual and combined contribution from the parameters were evaluated on its significance in affecting seismic performance.
Keywords: Seismic Isolation, Soil-Structure Interaction, Displacement Based Design.