Research On Simulation And Calculation Theory For Prestressed Concrete Box-girder Bridge With Corrugated Steel Webs

Compared with general concrete box-girder, box-girder with corrugated steel webs (CSW), which feathers light self-weight and high pre-stress efficiency, has been soon applied in bridge construction. According to the mechanism of box-girder with CSW, a practical computation method is proposed based on beam element finite element analysis, taking into consideration of the effects of bending, torsion and distortion deformation, for calculation of box-girder with CSW. And corresponding element stiffness matrix is obtained.Firstly, deformations of top and bottom flanges are assumed to be different freedoms in establishment of displacement function of beam due to bending deflection. The differential equation and corresponding element stiffness matrix of CSW box-girder are obtained based on virtual work principle. The treatments for pre-stressed tendons and connection between concrete box-girder and CSW box-girder have been discussed either. Convergence and precision of the proposed method are validated by numerical examples. Deformation characteristics of CSW box-girder are studied and compared with that of general concrete box-girder through parametric analysis.Secondly, Based on the torsional theory of general box-girder, the computation method for pure and warping torsion of CSW box girder has been proposed. The element stiffness matrix for torsion deformation of CSW box girder has been established according to the analytical solution of the basic function. A numerical example is provided to validate the precision of the proposed method. And the characteristics of tortional deformation for CSW box girder are studied, which offers a good reference for bridge design.Thirdly, the distortion calculation theory for CSW box girder is also proposed in this paper. The distortion equation, which can be used in distortion calculation of CSW box girder with rectangular or trapezoidal cross-sections, is established with virtual work principle. Corresponding element stiffness matrix is obtained analytic method. Different from the general distortion calculation theory, it is not necessary to calculate the distortion load with load decomposition according to the proposed method. And the versatility and precision of this method are proved to be pretty good.At last, the stress condition of the CSW box girder bridge over Yong Xin River of Ningbo is analyed with a general finite element program. Results show the shear lag effect for CSW box girder is not so obvious than that for general box girder. Besides, and the longitudinal strain of CSW box girder during deformation obeys with the plane section assumption.