Seismic response analysis on city overpass bridge

The seismic response analysis on the Xinlipu overpass, the Second Ring Road of Shenyang, was carried out to study the impact of earthquake on city overpass. The finite element software MID AS was used to model simulation analysis on Xinlipu overpass, which can obtain the displacement, stress and dynamic characteristics under effect of earthquake load. The first 30 modes of the bridge were analyzed. The results showed that the midspan nodes have both X direction and Y direction displacement, which illuminate that box girder bridge surface both have translational and vertical motion. Stress concentration appears in the 3 places on concrete pier, both side of the root of Y type pier inclined leg and the section of oblique shear upper connecting. The stiffness of bridge is high, the vibration cycle is short, the natural frequency is big, the intrinsic frequency growth is rapid and the modal is sparse. Under horizontal seismic waves, the horizontal and vertical directions have very sensitive response, the piers endure great stress force, and some measures should be adopted to avoid the phenomenon of stress concentration.