Analysis And Research Of Impact On Shear-lag Effect Of Wide Concrete Box Girder From The Prestress

With the rapid development of urban construction and transportation, traffic infrastructure construction scale is increasing. Three-dimensional prestressed concrete wide box girder has been rapidly developed both at home and abroad. Although three-dimensional prestressed concrete wide box girder has good structural performance, due to the use of three-dimensional prestress, the stress of concrete wide box girder is more complex, especially after considering the shear-lag effect of the structure.In order to find that longitudinal prestress affect the shear-lag effect of the concrete wide box girder, this paper firstly bases on the idea of first disassemble wide box girder then discrete combination, the energy variational method and the principle of prestress force converted to the equivalent load to take the theoretical derivation, after that the theoretical calculation method and formula are given. And through example, the reliability of the formula is verified by comparing finite element analysis, the final analysis conclusion and the actual design suggestions are given.Then this paper has carried on the analysis and research of the horizontal, vertical prestress affect the shear-lag effect of the concrete wide box girder by using finite element analysis.This research bases on one equivalent-width continuous cast-in-site box girder obtained by mainline first section of the Xinhua Street on industrial park of Suzhou central expressway project for engineering examples. Using Midas Civil and FEA, respectively, set up this box girder longitudinal bar-system finite element model and solid finite element model to analyze it. Results show that in equivalent-width continuous concrete box girder bridge setting horizontal prestress on the influence of shear lag effect cannot be ignored. Horizontal prestress produces similar positive shear lag in box girder roof and similar negative shear lag in box girder floor. But equivalent-width continuous concrete box girder bridge setting vertical prestress on the influence of shear lag effect can be ignored.