Analysis On Main Effect Factors Of Long-term Deflection Of Pre-stressed Concrete Beam Bridge

Pre-stressed concrete structure with its lightweight structure and the advantages of large carrying capacity are widely used at home and abroad. However, with the rapid economic growth and the increasing traffic, the problem of these structures are excessive mid-span lag in the operating period, it has a negative impact on safety of the use of performance to the bridge structure. And it becomes a serious impediment to development for such a bridge. It also urgently needs professors of bridge to resolve these technical issues. So for this problem, it analysis and studies the main factors of the impact of long-term deflection to a bridge structure. An example of bridge is used to clear various factors to time course of changes in the law and analysis its causes. It clears various factors for the impact of various factors for the degree of long-term deflection. To establish the foundation of the long-term deflection prediction and evaluation of the safety of bridge.In this paper, based on current domestic and international long-span pre-stressed concrete beam bridge status of excessive mid-span lag, it clears the main factors of long-term deflection of cross-bridge structure, which are duplication of the load, concrete shrinkage and creep and the pre-stress loss of steel beam. Firstly, thesis has summed up the mechanism of concrete shrinkage and creep, and respectively summed up the calculation model of concrete shrinkage and creep and their respective advantages and disadvantages. At the same time, it introduces the existing norms on China's calculation of concrete shrinkage and creep. And then introduce the pre-stressed loss of steel beam, the impact of the deflection for the pre-stress loss of top and floor steel. And it introduces the calculation of the existing norms of pre-stressed concrete girder bridge method of long-term deflection in China.Thesis uses a bridge structural analysis software for a large full-span pre-stressed concrete rigid frame bridge to make a full-bridge simulation, and analysis the impact of structure in duplication of the load, concrete shrinkage and creep and the pre-stress loss of steel beam, Obtain various factors to time course of changes in the law.