Stochastic Analysis About Long-Term Deflection And Stress Of Long-Span Continuous Rigid Frame Bridge On High-Speed Railway

The prestressed concrete continuous rigid frame bridge is affected sensitively by concrete shrinkage and creep for its complex construction and structure system changes. The creep and shrinkage of concrete is easily impacted by lots of random factors, so its long-term effects show a remarkable randomness. Taking an existing bridge as engineering example, a stochastic analysis was carried out in the thesis about the long-term deflection and stress of long-span prestressed concrete continuous rigid frame bridges on high-speed railway, with consideration of several main random factors probably causing the long-term deflection and stress of bridges. The following studies are mainly involved:(1) Domestic and international research datas about concrete shrinkage and creep are widely collected. The generation mechanism, influencing factors and some latest research progress of concrete shrinkage and creep are summarized. The common prediction models of concrete creep and shrinkage are detailed reviewed.(2) Considering the affecting variables’randomness of concrete shrinkage and creep, a stochastic method for the structural long-term deformation was used as the analysis theoretical basics for this thesis which is a technique combining the Response Surface Method with Monte Carlo sampling.(3) Based on the above method, a stochastic analysis about the long-term mid-span deflection and structural stress of high speed railway bridge was conducted in this thesis. The statistic characteristics and the probabilistic prediction of structural deflection and stress were achieved. The result indicates that although the long-term deflection and stress of long-span prestressed concrete continuous rigid frame bridges on high-speed railway show some randomness, but not so obvious. The results of this study have some good reference for the design of the same type highway bridge.(4) With response surface function, a sensitivity index of random variables is defined. It can be found that the structural deflection and stress is sensitive to the randomness of sustained load and stretching control stress.