Study On The Loading On Influence Surface Of Curved Prestressed Concrete Box Girder Bridge

In this paper, the study of live-load loading method for the curved prestressed concrete box girder bridge is introduced. The concrete contents are as follows:Firstly, longitudinal components of the Curved box girder have been separated into curved beam element, horizontal components have been separated into a straight beam element FEM model. Spacial Element stiffness matrix, equivalent nodal loads matrix and Coordinate transformation matrix for a curved beam element,involving six degrees of freedom in each node and taking effect of transverse shearing deformation into account,have been formulated,using Castigliano's theorem and mechanical method, and the module for grillage static analysis is formed,by using table of information of nodal point restraint to assemble stiffness matrix for structure in restraint. The program,which can deal with principal and subordinate degree of freedom,elaxtic support and constrained displacement rapidly and effectively, is the necessary calculation module of forming the influence surface of the internal force for grillage by kinematic method.Secondly, Based on the Muller-Breslau principle, formulars of equivalent nodal loads for the curved- and straight-beam element while occuring unit relative constrained displacement have been deduced.The influence surface of the internal force for grillage has been analyzed by combining kinematic method with finite element static method,using the superposition principle applied to Line flexibility.Compared with the static method and kinematic method computing deformation directly,the method presented here bring high efficiency when calculating the influence surface of the internal force for curved-bar grillage.Thirdly, The fundamental principle of loading of influence surface for straight-bridge is expounded by using the mixed method of dynamic programming and exhautive taking,and which is extended to the loading of influence surface for curved-bridge by quoting the idea of equivalent influence surface.To improve computing precision,the latter applies interpolating function of curved-quadrilateral element containing six nodes to thicking the influence surface of grillage, compared with lagrangian interpolation for rectangular element and triangle plane interpolation,this way not only improves computing precision but also be more suitable for the curved-bar grillage analyzing method introduced this paper.Finally, the paper has written the above contents into common computing programs with language Fortran77 and finished an integrated module for the calculation of internal forces for the superstructure of curved-beam bridge when analyzed by curved-bar grillage finite element method, and the module is Compiling, debugging, running Under the integrated development environment of Fortran Powerstation 4.0. One example presented have proved the validity of the theory, the arithmetic and the enough precision of the given programs.