The Study Of Shear Performance Of Ultra-long Span UHPC Continuous Girder Bridge

Ultra-long span UHPC continuous girder bridge makes improvements on thebasis of the conventional continuous girder bridge, it makes a good use of the UHPCto realize the mechanical requirements of the ultra-long span bridge, at the same time,it improves the form of structure and the prestressing system. This scheme makes afull use of the material advantage and improves the mechanical property of thestructure.The most important features of this bridge are that it’s very thin and only setlongitudinal prestressing. At the same time, the dense diaphragm plates are used toimprove the structure’s mechanical performance, which is hoped to ristrict thetorsional stress, transverse stress, and shear stress of the web as well as to improveshrinkage and creeping properties. The main content of this paper is to study the shearperformance of the web’s, mainly on how the diaphragm plates affecting the shearbehavior of the webs; to inspect if the webs of the box girder can satisfy the structuralrequirements of the continuous bridge whose span is up to400m. In view of this, theauthor has done the following work:（1）Design UHPC cantilever beam for shear experiment, one end of the beamhas diaphragm plates while other one has no diaphragm plates, study the whole courseof shear failure of the two beams through the experiment, to inspect the effect ofdiaphragm plates on the crack resistance and bearing capacity of the structrure.Experiment results show that cracks development of beam with diaphragms is slowerthan ordinary beam’s, diaphragm plates can significantly improve the crackingresistance of the beam.（2）Establish finite element analysis model basing on the experiment beam tocarry on the numerical analysis of the beams, to inspect the performance of thestructure in detail, such as the stirrup and diaphragms. Understand the effects of thediaphragm in-depth, obtain the structure’s bearing capacity. Analyze the effects ofseveral important parameters on the bearing capacity of the two structures. The finiteelement analysis shows that diaphragms can obviously improve the bearing capacityof the beam.（3）Introduce the overall force of the continuous girder bridge whose span is upto400m span, as well as torsion performance and the shrinkage and creep properties.（4）Basing on the global model, establish the local finite element model of the segment near the bearing to analyze its mechanical behavior, determine if the shearcapacity of the webs can satisfy the requirements of the box girder. The results showthat the principal tensile stress of the webs is relatively low, it will not make the webscrack, which means the girder can satisfy the force requirements of the ultra-longspan bridge.