Study On Warping Stress Of Corrugated Web And Steel Bottom Plate Composite Box Girder Under Restrained Torsion

The steel-concrete composite box with corrugated web and steel bottom plate is a new type of bridge structure,which replaces the concrete floor of traditional corrugated web composite box girder with corrugated web.It has more reasonable force,lighter weight,larger span and higher economic benefit.The steel bottom plate and corrugated steel web can be prefabricated and assembled in the factory,which can not only better ensure the manufacturing accuracy of each component,but also make the field construction easier,and facilitate the later maintenance and replacement.It has been put into use for the first time in Gansu Province.Therefore,it is of great significance and value to study the warping stress of this kind of structure.Based on the major science and technology project of Gansu Province in 2019 "complete set technology research and industrialization of highway new steel concrete composite bridge construction",the warpage stress of the structure under restrained torsion is studied by using the methods of theoretical analysis,model test and finite element simulation(1)Based on the V.Z.Vlasov generalized coordinate method,the spline finite point method and energy variational principle are used to analyze the warping stress and the calculation method of it under restrained torsion.The warping stress of it is theoretically derived.(2)Detailed design and manufacture of model dimensions and test points were carried out.The warping stress,torsional distortion coupling shear stress and partial load factor were obtained through model tests.Through the analysis of the experimental results,it is found that the warping stresses of the roof and the bottom plates of the corrugated web steel bottom plate composite box girder under restraint torsion are asymmetrical distribution with respect to the center line of the bridge.From L/4 section to L/2 section,the coupling normal stresses of the top and bottom plates increase;the torsion and distortion coupling shear stresses are symmetrical distribution and increase to both sides with respect to the center line of the bridge.The stress distribution on the web is relatively uniform,and the shear stress of corrugated steel webs is decreasing from the cross section L/4 to the L/2 section.(3)It is found that the partial load coefficient of this kind of structure is between 1.37 and 1.48 in the mid span section,which is much larger than that of ordinary concrete web beam,indicating that the partial load effect of this kind of structure is more significant than that of ordinary concrete beam by the model test,.It shows that the eccentric load effect of it is more significant than that of ordinary concrete beam.The normal stress increasing coefficient of this kind of structure is in the range of 1.56 ～ 1.58 in the mid span section,and the shear stress increasing coefficient is in the range of 1.44 ～ 1.46 in the mid span section,which indicates that the torsion and distortion effect of this structure is more obvious than that of traditional corrugated web composite box girder with corrugated web.(4)Different beam end constraints are added to the finite element model of steel-concrete composite box girder bridge with corrugated webs to analyze the influence of different constraints on the warping stress of steel-concrete composite box girder with corrugated webs.With the end restraint of steel-concrete composite box girder with corrugated webs strengthened,the warping stress on the top plate and bottom plate of mid span section decreases,and the shear stress on the web decreases.In this paper,the warping stress of steel-concrete composite box with corrugated webs under restrained torsion is studied.The research results have certain engineering reference significance for the design and construction of this kind of structure.