ABSTRACT
This paper presents a replacement of existing steel bearings by isolation rubber as a seismic retrofitting measure to a part of the Hitsuishijima Viaduct in Seto-Ohashi Bridges, which had not been applied for highway-railway combined bridges in Japan. According to seismic performance evaluation, it was found that some members were damaged. In order to minimize retrofitting work over the railway tracks, the isolation of truss girder was selected. In order to isolate the truss girder, the constraining effect of the long rail and the safety of running trains were studied. In the retrofitting work, in order to minimize the impact on the expressway, railway tracks and utility facilities, the change in structural system due to the isolation rubber bearings and the displacement of truss girder by jack-up had to be studied. The support structure was adopted with a knock-off mechanism, and the effects of jack-up were confirmed by FEM analysis.
