Analysis Of Shear Lag Effect For Wings Large Cantilever Inclined Web Prestressed Concrete Continuous Box Grider

The large urban bridge is one of the symbol of modernization of the city. The design concept should keep up with the time, making this artificial structures to be coordinated with urban natural and cultural environment.On the premise of meeting the demand of traffic function, improving or enhancing the urban environment around the project through making the bridge forms to be more sophisticated, beautiful. Large wings cantilever box girder structure is beautiful and graceful which shows important trends in civil engineering. But we are not particularly clear about its mechanical characteristics. So making detailed stress analysis to better guide the design of the new bridge is necessary. This thesis is based on a recommended bridge type (skew web large cantilever box girder with wings which use precast assembled construction method of prestressed concrete) in a bidding plan for a rapid reconstruct project of a certain section of national highway. Use the bridge structure design system (SCDS) to establish the plane truss model and ANSYS to build spatial finite element model and make a certain analysis about the shear lag effect of the researched objecet. The main work and the content is as follows:1. After read current information, understood the principle of shear lag analysis and special laws, made a summarizes about the advantages and disadvantages of research methods and determined the Analysis solution.2. With the use of SCDS, the plane truss model was established, the design and construction of structure was checked and the stress characteristics was analyzed.3. By using ANSYS, the entitative spacail model was established. SOLID185Unit was used to simulate box girder, transverse beam, stiffener plate insulation and LINK180Unit was used to simulate the prestressed steel beam.4. Compared and analysed the results of counter-forces, normal stress and deflection which comes frome the models of SCDS and ANSYS. Verified the entitative spacail model of the bridge to be reliable.5. The entitative spacail model created by ANSYS was used to analyse the shear lag effect which was under the load of individual and various combinations. The contents include:the analysis of transverse and longitudinal shear lag effect of box girder, the comparision of the result of limited distributed width with《The Highway Reinforced Concrete And Prestressed Concrete Bridge Design Specifications》(JTG D62-2004) and the summary of the laws.6. Considering the particularity of the shear lag effect caused by prestressed load, examed the prestressed primary force and secondary force separately. Finally, valuable conclusions are drawn.