The Seismic Response Study Of The Jinzhou Bay Bridge â…¡

Being as a special bridge structure, the self-anchored suspension bridge is more favorable for bridge engineering because not only it remains the aesthetic linearity and well-order appearance of earth-anchored suspension bridge but also it is free from the impaction of geographic conditions. The Danlian Jinzhou bay bridge II which located in Jinzhou District of Dalian crossing Jinzhou Bay is the main part of the construction of Binhai Highway and it will become a signed architecture after constructed. Thus, the accurate and effective aseismic design of Danlian Jinzhou bay bridge II appears significant to ensure its aseismic safety.Employing the coupling and prestressed functions in ANSYS procedure, a 3-D finite element model is successfully established to simulate the boundary conditions and initial states of Danlian Jinzhou bay bridge II and the seismic response analyses is conducted in some degree. The work completed in this paper are as follows:(1) The analyses of the natural vibration characteristic of Danlian Jinzhou bay bridge II is performed and the main natural frequency and vibration mode are obtained, the natural vibration period determined in the low order mode of the bridge is longer. The first mode is longitudinal floating. The vibration modes of this bridge are close each other, the vibration of the main girder is the main characteristic of the previous eight modes.(2) The seismic response of the bridge is computed by making use of the response spectrum method. Basing on the input adopted both the response spectrum prescribed by regulation and the new response spectrum obtained after long period and damping ratio calibration, the seismic response is computed under the longitudinal, lateral and vertical direction respectively. The longitudinal and vertical vibration of the main girder and tower are the main response under the action of longitudinal input. The lateral and torsional vibration of the main girder and tower are the main response under the action of lateral input. The vertical vibration of the main girder and the vertical and longitudinal vibration of the tower are the main response under the action of vertical input. After that, the seismic response for the bridge under the function of three direction orthogonal component is computed. From the results we can see that the combination of the longitudinal and vertical is must be considered(3) The time history analyses of seismic response on the bridge is made. The results of time history analyses is compared with that of the response spectrum method. In general, the results of seismic response is consistent, but some results have a greater difference, so, the time history analyses is necessary. After compared with the results of the static analysis, we can see that the results of the seismic response control design.(4) At last, through the response spectrum method and the time history analysis method, the study on the impaction of the seismic response for the bridge to set longitudinal elastic restraint is carried out. The response will be increased after set longitudinal elastic restraint, but the displacement of the main girder and tower distinct decrease if set appropriate longitudinal elastic restraint, and the bending moment of tower and tower beam joint are improved. so, if we can find the appropriate longitudinal elastic restraint, the internal force and the displacement of the bridge will meet the requirement of the permissible value.The study conclusions in this paper can be treated as a reference basis for the aseismic design and make a guiding significance for the seismic response analyses on other similar bridges.