Natural vibration and nonlinear seismic response properties of continuous truss bridge (the lkitsuki Bridge)

The Ikitsuki Bridge，which connects Ikitsuki Island and Hirado Island in Nagasaki, is a through-type continuous truss bridge with three spans. The main span is 400m and the side spans are 200m. In the case of a truss bridge，there is a possibility that a member may yield under a Level 2 strong earthquake. This paper examines free vibrations and nonlinear seismic responses of this bridge using a three-dimensional finite element model. The nonlinear seismic characteristics and seismic safety of this bridge subjected to the Level 2 ground motions are examined in detail. As the result, it is found that some members in lower chord and upper chord yield under strong ground motions