Structural Analysis And Optimal Study On Y-Shaped Continuous Steel Box Girder For Urban Overpass

In the background of the Ramp D of Chengdu Three-Ring Overpass near Shahebao New Railway Station, structural analysis and optimal study on a Y-shaped continuous steel box girder are presented in this thesis. Firstly, structural features of several typical Y-shaped girders for urban overpass are summarized. A detailed spatial finite element model of the whole bridge is built up with plate element and brick element using the large scale software ALGOR. Based on the model, some analyses are made to obtain the detailed stress distributions of the bridge components under the action of the vehical loads, the temperature load and forty-nine kinds of combinations of these loads. Considering the excessive stresses of some plates for original design, optimal proposal, including to thicken bottom slabs, webs and diaphragms, and to add horizontal ribs, is presented and analysed. Using sparse matrix method, the natural frequency and vibration mode are obtained. Subsequently, spectrum analyses are carried out to obtain seismic responses. To simulate the transition of main lane and divided lanes, three finite element models, which involve beam elements, are developed using the finite element software called MIDAS/CIVIL2010. Likewise, spectrum analysis and time history dynamic analysis are performed to probe into the seismic responses, and the results are compared with those of previous researches. Finally, the deviation of pier during the construction and corresponding solutions are discussed in this thesis. Therefore, the static and dynamic performances of Y-shaped continuous steel box girder for urban overpass are comprehensively understood, and analysing method of complex bridge is mastered.