Abstract
This work is concerned with the configuration and deformation of prestressed cable nets treating the nets as discrete systems. The treatment is as follows. Chapter 1 describes briefly the three main different types of cable systems used in the design of cable roofs, viz. 1) Simply suspended cables, 2) Cable girders, and 3) Cable nets. Chapter 2 deals with the initial configuration of nets for which the prestressing forces are assumed known. The main emphasis is given to closed forms of solutions because of their suitability to electronic computation. In Chapter 3 is developed a theory which will calculate the displacements and forces in any type of pinjointed link assembly, both rigid and non-rigid, subjected to any type of loading. The application of the method is based upon the minimization of the total potential by the method of steepest descent. Since the method of steepest descent was found to converge very slowly a great deal of time was spent investigating this method with a view to increasing the rate of convergence. The result of this work is given in chapter 4. Inthis chapter it is also shown that another possible way of locating the minimum total potential is by the Runge-Kutta method. The validity of the deformation theory was demonstrated by testing a flat net and a doubly curved net. The design of the model, the test results and corresponding theoretical values are given in chapter 5. In chapter 6 are given the results of an analysis of the behaviour of small saddle shaped nets carried out to investigate how the stiffness is affected by curvature and intensity of prestress. In chapter 7 it is shown how a chosen configuration can be calculated by the theory given in chapter 3. Where appropriate, conclusions on the different aspects of the work are given at the end of each chapter. A summary of these conclusions is given in chapter 8 together with suggestions for future work. Because of the very large number of tables, graphs and diagrams, these have, as far as possible, been included at the end of the thesis, as shown in the contents.