The Cracking Factors Analysis Of Prestressed Concrete Box Girder Bridge

When we build bridge it’s easy for us to choose prestressed concrete box girder because of it’s a series of advantages such as: good integrity, greater torsional stiffness, adapt to a variety of modern construction methods etc. There are some box girder bridge diseases as more and more girder bridge having been put into operation. Of all the diseases, various cracks in the concrete is a representative one. The appearance of cracks influences the beauty of the bridge. More importantly it influences the safety and durability of the bridge. Therefore, taking two prestressed concrete continuous rigid frame in Shanxi Province as an example, through finite element model, this paper analyzed the cracking Factors of the bottom plate and webs of prestressed concrete box girder bridges. And then this paper made recommendations for improvements from the respect of design and construction. The main contents are as follows:Firstly, this article describes the development of the box girder bridge and the trends of future. Secondly it introduces the cracks problems arising in the box girder bridge, and specially introduced the cracks appearing in the web plate and base plate. Then through checking the information this article made us know that the research and the achievement done by scholars. It also made us know that there are still problems.Secondly, this article presented the space mechanical properties including the deflection, the torsion, the distortion and the shear lag affect of the box girder. This article also presented the analytical methods of box girder to make a clearer understanding of the mechanical behavior of box girder bridges and provide a theoretical basis for the analysis.Thirdly, relying on the actual project, this article analyzed the cracking Factors of the box girder webs. The analysis includes the vertical prestressing, the set of the web reinforcement and the thickness of the web. The analysis researched on the impact of various factors on the stress of box girder webs. And this article proposed some measures for improvement.Fourthly, take closure segment as an example, relying on the actual project this article analyzed the cracking Factors of the box girder base plate. The analysis includes the transverse arrangement of the reinforcement, the parabolic curve index of base plate, the thickness of the base plate and the set of diaphragm. The analysis researched on the impact of various factors on the stress of box girder base plate. And this article proposed some measures for improvement.