Concept of Seismic Retrofit of Minato Bridge
Innovative Seismic retrofit is conducted adopting "damage controlled design" by means of seismic isolation and vibration-damping technologies.
Seismic isolation slide bearings, instead of metal bearings supporting the bridge deck, were installed to decrease the effect of earthquakes and thus protect the main truss from damage.
The sway bracing and lower lateral bracing were replaced by "buckling restrained bracing" to avoid buckling and absorb seismic energy.
Buckling restrained bracing: core member is made by low yield-point steel (LY225) and it is covered by a restraining member in order to prevent from buckling by ordinary axial force.