Research On The Impact Of Non-uniform Shrinkage On Long-term Performance Of Concrete Beam Bridge

In recent years, large span prestressed concrete box girder bridge structure is becoming more danerous because of down-warping, the reson leaded for this phenomenonresult the is still not completely clear.The analyse is based on concrete shrinkage and creep, cracking effect of box, existing computing and conuntmeasure and so, current research summarizes and Comprehensive Assessment large on span prestressed concrete box girder bridge issue is put forward down-warping .The main reason resulted in down-warping and difficulties is discussed by its mechanism. It illustrateed that the deflection is general existing in main beam, which indicate that prestressed concrete box girder under the flawed system to some extent. Different regions, the difference between the material and the environment , the distinction between the construction quality of a particular factor is not necessarily caused by Deflection.In response, Non-uniform shrinkage of the concrete box girder bridge deflection under long-term use had a significant role. The study shows that: 1. Cantilevered box girder structure under non-uniform contraction, thin roof and floor will be a party to the bending, and peak around 4000 days, and then bending deformation gradually decreases until the state of Liangping straight; 2. continuous beam structure in the role of non-uniform contraction, due to the impact of boundary conditions can not be free in the axial stretching deformation, and thus the secondary stress the role of the deformation caused by creep and shrinkage and creep interaction, so that Change the value of the convergence of a final deflection; 3. webs connecting the roof and floor of the connection component, it can coordinate the roof and floor deformation and material properties according to their formation of strain gradient between the roof and floor, which can be reduced by changing the web material or even eliminate the deflection change.