Prestressed Continuous Box Girder Crack Analysis And Safety Assessment

Except for all the advantages of ordinary reinforced concrete bridge continuous prestressed concrete box girder bridge have some specifications, such as small in section, light in weight, economic in material, lasting in durability and so on.Large-span continuous prestressed concrete box girder bridge has been a great deal of development with the appearance of more sophisticated, high-strength concrete soil, and high-strength reinforced materials.In China, since1970s, the prestressed concrete box beam bridge has improved quickly as the rapid development of the transportation business, becoming the main form of prestressed concrete girder bridge cross-section and applying widely in modern bridge design.However, due to various factors, many prestressed continuous box girder bridges have been cracked in varying degrees. Therefore, it is of practical significant to analyses serious cracks in the prestressed concrete continuous box girder bridge Cracks, to establish steady analysis of the bridge based on the crack situation, and to assess finally the safety of the reinforced bridge.This thesis takes prestressed continuous box girder bridge cracks of Xiangjiang as the research background to analysis the following aspects:1. On the basis of full understanding of the history, development and structural characteristics of prestressed concrete continuous box girder bridges, preliminary analysis of these causes for the typical cracks at domestic and abroad will be carried out. from the perspective of raw materials, materials, environment, design and construction and so on.2. Applying the ANSYS finite element software to establish the bridge model of Xiangjiang. And then we will analyses the crack based on the assumption of the overloading model. Finally, we will compare the results of the actual bridge crack detection to get the root causes of the bridge cracks.3. Taking the most severe crack,56#～57#cross-web crack on Xiangjiang bridge as the example, the thesis establishes the normal distribution model of crack width data, and then tests the assumption distribution by mathematical tools x2to ensure95%of reliability analysis of the largest width of cracks.4. Through the analysis of the damage characteristics of reinforced Xiangjiang River Bridge, we will obtain the safety performance of the whole bridge by bringing in reasonable quantification of the large number of test results based on the variable weight of the Analytic Hierarchy Process. Finally, we will get effective safety assessment and take appropriate measures to the security posture of the bridge.