A thesis submitted in partial fulfillment of the requirements for the degree of master of engineering, school of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1980

A numerical scheme incorporating the finite strip-flexibility approach in conjunction with the substructure technique is proposed for static linear analyses of straight cable-stayed bridges. In this approach the whole bridge is treated as an assemblage of two substructures, a continuous box girder substructure and a cable-tower substructure. The vertical deflections at the cable-girder connection points and at a finite number of load points are taken as the reduced degrees-of-freedom of the girder substructure. The effect of axial deformations in the box girder is neglected for simplicity. For the cable-tower subsystem all degrees-of freedom at the joints are considered with appropriate boundary conditions taken into account. The flexibility matrix of the box girder (with intermediate supports and diaphragms) is obtained by using the finite strip method in conjunction with the flexibility approach . The reduced stiffness -matrix of this system, evaluated by inverting this flexibility matrix, is then assembled with the stiffness matrix of the cable-tower. substructure. The latter is obtained by the standard finite element procedure, with the cables modeled as truss elements and the tower as segments of beam elements. A cable stayed box girder bridge was analyzed to evaluate the advantages and disadvantages of the proposed scheme as compared to the finite element method, The analysis procedure gives sufficiently accurate estimate of the stiffness of the cable-stayed bridge and is competitive to the finite element method in terms of computation efficiency.