Control Of Cracks In The Construction Of The Wide Prestressed Concrete Continuous Box Girder Bridge

With the rapid development of the infrastructure construction such as highway and municipal engineering,the prestressed concrete continuous girder bridge get rapid development and wide application.However,due to the unreasonable factors in aspects of design,construction,some bridge in construction or operation stages appeared various forms of cracks,especially after the bridge width increases,the problem of cracks in the construction process is more prominent.In order to solve the problem of relying on the project of construction cracks,this article launches the research from the following aspects:First according to the related domestic engineering examples,and the relies on the project of the engineering construction,this article carried on the thorough analysis of cracks in cantilever construction of box girder bridge.And through the contrast experiment,determined primarily affect the influence factors of crack.Secondly,analysis the mechanical performance of early concrete,considering the concrete elastic modulus,tensile strength changes with age of concrete.And simulation analysis from the gravity,environment temperature,hydration heat,hanging basket,prestressing.Focuses on analyzing longitudinal and lateral to the stress distribution of bridge box girder,determine the major cause of box girder bridge construction cracks appears.Analysis showed that environmental temperature,settlement of hanging basket,hydration heat,transverse reinforcement and width of box girder cross section are the major cause of construction cracks.The influence of environment temperature on cracks performance in,when the temperature falls box roof can appear longitudinal cracks;The influence of hydration heat on cracks performance in the heating period,the surface can appear transverse crack,in the cooling phase,under the roof and floor surface will occur longitudinal cracks;When the box girder cross section width is reduced,the longitudinal cracks won’t appear under different conditions.And the hydration heat have a great influence on construction cracks.Last to solve the wide box girder bridge construction crack,this paper proposed crack control measures from hanging basket,temperature control,construction process,transverse reinforcement and other aspects.To seek for the economic and reasonable prevention measures,the scene through the contrast test,through contrast to determineall aspects wide box girder of bridge construction crack control measures in the end.And summarizes the fracture treatment measures,put forward some matters needing attention in the design and construction of similar bridge.