STABILITY OF CABLE-STAYED STRUCTURES

Abstract

This thesis deals with the stability analysis of three-dimensionl cable-stayed bridges and guyed towers, taking into account the effect of semi-rigid connections and the ineJasticity of cables, as well as the plastic behaviour of the structure until reaching collapse. A historical review on the analysis and types of cable-stayed structures, their development, construction, and main elements is given. An extensive literature survey demonstrates the different shapes of guyed towers, and their cables' arrangement. A computer program in "FORTRAN" has been developed using the potential energy of the stayed girder, through an iterative procedure. Several examples of cable-stayed bridges have been solved to check the program results, and to draw the deformed shapes and bending moments. A three-dimensional numerical procedure has been explained for predicting the nonlinear stability analysis of cable-stayed structures. This analysis is based on minimizing the total potential energy of the structure, using the conjugate gradient method in conjunction with the Newton-Raphson iteration scheme, to satisfy the required joint equilibrium conditions. A new technique has been developed for the numerical simulation of semi-rigid connections. Another computer program is established to take into consideration the geometrical nonlinearity, as well as the effect of the flexibility of connections.