The Research On Crack Of Box-beam In Prestressed Concrete Bridge

In recent thirty years, the long-span PC continuous box girder bridges have been widely used. They take great proportion in bridges around our country and abroad. They have the advantages of great anti-wrest stiffness, working whole well, enduring positive and negative bending well. The method of construction is mature and easy to mastering. But in many constructed bridges, there are a great deal of cracks in their constructing process or after their construction. It severely affect the normal work of the bridge. There are several contents of research about PC continuous box girder bridges in a following part. 1. After investigating many datum of theory and experiment in reinforced concrete, analyzing and comparing all kinds of models about constitutive equations in concrete, it is decided to do the analysis of damage in box girder by using the theory of damage. 2. After concluding all kinds of cracks in PC continuous box girder bridge, the characteristic and cause of cracks are analysed so some method can be taken to control crack. 3. When using the theory of damage mechanics, the damage constitutive equations derived directly from thermodynamics is adopted to do following analysis. 4. Based on the ANSYS software, a model is established by moderately-thick shell to calculate the stress and strain of box girder by self-weight after constructed, analysis the influence of shearing force lag in box girder, get the relation of the stress in box girder and the thickness of box girder, offer foundation to select the thickness of ventro-plane. 5. In order to applying the theory of damage mechanics to the research of bridge, exploring study is done. Box girder in space is simplified to plane problem to solve the calculation about damage. The speciality of bi-axis stress and the change of material performance in dissimilar situation of damage is account to accomplished the numerical calculation of damage in box girder.