Simulation Analysis On Cracking In Bottom Flange Of Large-Span Continuous Box Girder Bridge

In recent years, with the rapid increases in traffic demand in China, prestressed concrete continuous box girder bridge,with its superior performance has been widely used in China bridge. However,in the construction or operation of the process, a considerable number of box girder various forms of cracks have appeared in the roof, the web, the bottom and other parts, especially bottom cracking,which become an important factor to hinder its development, which also caused the engineering and academic attention. These cracks have a very negative impact on the durability,practicality and safety of the structure.This article relies on the Guangxi a double-track railway bridge, using the finite element program of the prestressed concrete bottom cracking of continuous box girder bridge is analyzed and verified. In this thesis, the research work includes:(1) On the basis of a lot of reading literature, made a presentation at home and abroad prestressed concrete continuous beam overview of the development and the bottom slab crack research, emphatically analyses the formation reasons and countermeasures of bottom crack.(2) In this thesis, the finite element analysis of box girder theory is presented, and the content of the thesis is to Guangxi a double-track railway bridge bottom cracking project, according to the on-site observations showed that bottom prestressed pipe floating is the main reason for the accident. Through the establishment of the overall bridge model,the strength and stiffness are calculated. And then create a local space model, through several conditions of bottom stress analysis and comparison, verify the right of bottom prestressed pipe floating phenomenon caused coincide with the accident. Finally, this thesis gives a few prevention advice and reinforcement measures on bottom cracking.