Research On The Vertical Joint Of PC Concrete Box Girder Bridge

With the development of science, technology and traffic enterprise, the prestressed concrete (PC) box girder bridges ridge has been growing up rapidly in the recent years with its unique predominance of handy construction, economical cost, reasonable internal force and comfortable traveling. In as much as the finished long span prestressed concrete continuous beam bridges usually constructed with segmental cantilever site cast construction method,which inherently has vertical joint between segments, its construction technology and joint quality will have significant effect on the structure of continuous rigid frame bridge. These factors have not been considered in the design and the calculation is doing according to the ideal no-jointing structure in structural analysis. There are several joints in the practical construction and the performance of structural mechanics is weaker than one-time entire concrete pouring structure, thus create discrepancy between theoretic calculation and practical situation, which is not being considered in present design theory. Furthermore, the vertical joint between segments not only has a bearing on the integrity of bridge structure and later operational performance but also affects the appearance, bearing capacity and service life of the bridge. It also has seriously influenced traffic safety.This paper is based on the program of transportation developments in the West—"Research on Cause and Treatment Technology of the Contentious Box Girder Bridge and Continuous Rigid Frame Box Birder Bridge", and a series of experimental and analytical researches on Vertical Joint at Xiangjiang long-span bridge in hunan province. Through comparative study on different kinds of joint beam model and integrated concrete placement beam model , this paper explores the impact of roughness, reinforcement ratio, prestress and joint quality on model structure. After contrastive analysis of the results, it can be inferred that the joint quality, reinforcement ratio and the loss of vertical prestressing can significantly influence the whole structure, while roughness do not affect the structure but it must be paid enough attention. At last, the paper proposes an improving model based on the design of vertical joint.