Stochastic Analysis About Highway Prestressed Concrete Beam Deflection With Creep Effects

In many diseases of the prestressed concrete girder bridges,the lasting deflection is one of the most important diseases. The long-term deflection of concrete bridge will affect bridge driving comfort and safety, as well as the service life and durability of the structure. For railway bridges, especially the high-speed railway bridge, the long-term deformation of the bridge structure affect smoothness of line, and even the safety of trains. Because of the uncertainties resulted from the resources of concrete, a deterministic analysis approach for calculating the deflection of a concrete structure is likely to vary significantly from the experimental deflection. In the stochastic and reliability research, one usually focused on bearing capacity of the structure, but less for the structure of the normal state. The following studies are mainly involved in the present thesis from the most basic form of element-concrete beam bridge.First, based on those previous studies, the current prediction models and analysis methods of creep and shrinkage are summarized. The finite element software (CSBNLA) are introduced.The major random variables are introduced. Meanwhile, the basic theory of stochastic analysis and sensitivity analysis is introduced.Then, a piecewise response surface method is suggested. After the random analysis for immediate deflection and long-term deflection of reinforced concrete beams by MC method, MC with traditional response surface method and MC with piecewise response surface method, the results indicate that the piecewise response surface simulation performs well.Finally, coupling the non-linear finite element with Monte Carlo method, models for random analysis and sensitivity analysis of the whole process loading of prestressed concrete bridge are built. In addition the same model for considering the influence of time history of live load to prestressed concrete bridge deflection is built.The probabilistic-meaning prediction about deflection disciplinarian of bridge is given.Receach results show that, because of creep characteristic, the randomicity of deformation in concrete beam cannot be ignored. If deteterminstic apparoach is used, no results with probabilistic meaning can be drawn for the structure of normal state. Therefore, it is suggested that the randomness of input variables should be concerned in the long-term effect analysis.