Research On Causes And Mechanism Of Cracking Of PC Box Girder Bridge

Due to its resistance to stress and low cost advantages, PC box girder bridgesare widelyused for highway construction in China. During periods of bridge construction and operationmanagement, alternate sections of the box girders have shown different cracks.Without timelytreatment or proper treatment measures, cracks may have worsened, possibly leading todamage of the bridge, hence, ultimately shortening the life of the bridge. In this regard,engineering urgently needed to find the cause and answer to box girder cracking.Research into the development process and subsequent damage was done on samplesfrom both home and abroad to best assess a positive response..Using the Fujian Provence asan example, the typical crack was characterized by bottom longitudinal cracksfound in boththe Quanshan and Funing super highways.Design, material application, construction andoperational stages were all analyzed to seek the cause of the longitudinal cracking. In orderto further assess the effects of pre-stressed offset or pre-stressed super tension on the boxgirders,the author analyzed the calculation and simulation of PC box girder conditional useusing Midas Fea finite element software.Through the calculation of differing pre-stresseddeviation degrees and pre-stressed super tension, the author finallyconcluded that thepre-stressed tendons deflection or deflection and super tension are not caused bybox girderbottom longitudinalcracks.PC box girder bottom longitudinalcracks are more likely tooccur inthe construction period. Due to the density of the steel bars used, the concrete vibrator is notadequatelymixing the concrete and so the quality of the pour is poor. In the small box girder,later operations revealed that the bottom plate had been subjected to lateral force andgrewlongitudinal cracks. Finally,the author put forward some prevention measures,on thedesign stage, materials application, and both construction and operation stages.