Analysis On Mechanical Behavior Of The Fold-Line Pre-tension Pre-stressed Box Girder

The fold-line pre-tension pre-stressed box girder, is a kind of pre-tension pre-stressed concrete beams, which has begun to apply in bridge engineering in China in recent years. The fold-line pre-tension pre-stressed box girder not only overcomes the defects of pore filling not dense of post-tensioned pre-stressed beams, but also makes the shape of pre-stressed tendons of the broken line closer to the distribution of load moment, so it adapts to a fairly large scale. In addition, pre-stressed steel strand bend upward is part of the shear resistances, it can effectively prevents the inclined cracks.This paper, according to Chinese first highway bridge of broken line pre-tensioned pre-stressed concrete-the Huaihe River in Henan Zhumadian to Tongbai Highway Bridge Project; according to the pilot study, based on the use of large-scale finite element software analyzes stress state of pre-tensioned pre-stressed concrete box girder with the span of 35m and strand anchorage and zone of bending zone mechanical properties, and put forward corresponding measures for Chinese first highway bridge of broken line pre-tensioned pre-stressed concrete to provide a basis applications for engineering. The main thesis work as follows:(1)This article analyzes the mechanical behavior of pre-tensioned pre-stressed concrete box girder with the span of 35m under the vertical loads.(2)This article also analyzes stress analysis of anchorage zone of the fold-line pre-tension pre-stressed box girder.(3)This article analyzes stress analysis of strand bending zone of the fold-line pre-tension pre-stressed box girder.Finite element analysis results are as follows:(1)Pre-tensioned pre-stressed concrete box girder with the span of 35m has good ductility properties, and its crack resistance fully meets the design requirements. At all levels of loads, component deformation and bearing capacity of the numerical results and experimental values agree well. It shows that finite element method for the analysis of mechanical properties of these components is feasible.(2)Stress analysis of anchorage zone of box girder shows that failure to set pre-stressed in the end section, increasing the end web thickness and the ends of additional tensile reinforcement structure can effectively prevent cracking at the end of the box girder. Finite element analysis results are in good agreement with experimental results. No cracks at the end of box beam confirm the rationality of finite element analysis. It shows that finite element analysis can be as one of the partial stress analysis methods to analyze the stress of the anchorage zone of pre-tensioned pre-stressed concrete box girder.(3)The stress analysis of equipment changing the direction of box girder showed that using pull-plate bent is reasonable, concrete of strand bending area can not crack, which is consistent with the actual situation which does not crack. It shows that finite element analysis can be as one of the partial stress analysis methods to analyze the stress of bending part of strand.