Optimum design of redundant prestressed pin connected structures

Includes bibliographical references (pages 84-85)Nonlinear programming techniques developed in recent years for optimum structural design are time consuming for large systems. To overcome this difficulty of searching for minimum weight, a method of arriving at lower bound solutions to pin connected structures, by means of prestressing their redundant members is presented. The method employs linear weight equations derived from equilibrium considerations and stress constraints. Prestressed structures allow the designer an additional degree of freedom; he may control not only the shape of the structure and its cross-sectional dimension but also the level of prestressing. The methodology of prestressing is derived and formulated for single and multiple loading conditions. Prestressing of various truss configurations and application to bridge truss design is performed to illustrate the advantage and efficiency of the method. The significance of the number of redundant members and the choice of redundant members, as a means to reduce weight, has been established. A Monte-Carlo Optimization Computer Program has been incorporated as a tool" to obtain lower bound minimum weight solutions. These solutions can provide the structural designer with a guide in the selection of subset configurations for which upper bound solutions of reduced weight are sought