Performance-Based Seismic Retrofit Design of a Long-Span Truss Bridge—Minato Bridge—Using New Control Technologies

This paper describes performance-based seismic retrofit design for a long-span truss bridge, Minato Bridge in Osaka, Japan, against maximum credible ground motion, using new response control technologies. The target performance is the early reopening of the bridge after a severe earthquake; the main members that support gravity load should remain in the elastic region while sub-members may reach the inelastic region only within a moderate range. To achieve the performance criteria, new response control technologies are adopted: seismic isolation of floor decks for the longitudinal direction and buckling restrained braces for the transverse direction. Optimization of the design is also discussed. The retrofit design is verified by nonlinear dynamic analyses.