| In recent years, concrete-filled steel tubular arch bridge has been developing rapidly andapplied widely in China.Because it has unique combination of structure form and beautifulaesthetic appearance. CFST arch bridge meets the actual needs of the large-span bridges, andtakes good advantages of the properties of materials with reasonable project cost. Along withthe rapid development and wide application, it become more and more necessary to analyzethe bridge structure, the seismic response of CFST arch bridge and the complex key local ofbridge, so that the safety of construction process and the safety of long-term bridge operationcan be guaranteed.With the-122-meter-Zhengzhou-Jiaozuo intercity railway main span tied arch bridge asthe project background, the bridge professional analysis software MIDAS/CIVIL is adoptedin this study to build the plane bar system model and three dimensional bar system model ofbridge upper structure and MIDAS/FEA to build the three dimensional solid element modelof bridge upper structure. This analysis model is divided into28construction stages. Thedisplacement and strain of all the typical sections of the important construction stages selectedare analyzed. The analysis results provide the theoretical guidance to the actual constructionand demonstrate the stress values of bar system model and solid element model are largerthan the measured values in the construction stage, but they are consistent in the service stage.By using the bridge dynamic analysis of the established three dimensional bar systemmodel and the established three dimensional solid element model, the present study conductsa contrastive analysis of different models on period and amplitude. According to structuredynamics methods, structure earthquake resistance methods and <Code for seismic design ofrailway engineering> GB50111-2006(the modified version of2009), both the two models areanalyzed using earthquake response spectrum method and seismic time history method.Appropriate calculation method is selected after analysis. The analysis of the bridge is carriedout in five working conditions, which includes the working condition of independent input inlongitudinal direction, the working condition of independent input in transverse direction, theworking condition of independent input in vertical direction, the working condition inlongitudinal and vertical direction, and the working condition in transverse and verticaldirection. The some typical sections of the displacement and stress of the bridge’s structureare analyzed. The difference between different modeling methods in seismic response arecontrasted and analyzed. This study also attempts to summarize some useful conclusions. Itcan be known from the results that, in the seismic response analysis, the biggest verticaldirection of earthquake response spectrum analysis is larger than that of the biggest verticaldirection of seismic time history analysis. But longitudinal and transverse direction are significant in seismic time history analysis. In the upper part of CFST tied arch bridge, thevault is the relatively weakest part. Stress of the arch foot is the most unfavorable in thestructure system stress.In the present study, the bridge professional analysis software MIDAS/FEA is used forthe establishment of arch foot local model. With the finite element divided by hexahedron,two different working conditions are chosen and analyzed, and the result of the displacementand stress are summarized which shows the displacement and stress nephogram of concreteon arch foot without vertical prestress, the link location of beam, and concrete on arch footappears bad situation. |
