Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1991. / Vita. Abstract. Includes bibliographical references (leaves 85-86). Also available via the Internet.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005. / Oberle, Rita A., Committee Co-Chair ; Kahn, Lawrence F., Committee Co-Chair ; Baker, Nelson C., Committee Member ; Gentry, Russell T., Committee Member ; Molenaar, Keith R., Committee Member. Includes bibliographical references.

Thesis--Danmarks tekniske Højskole. / Errata slip inserted. "Dansk resumé": p. 266-268. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 157-163).

Thesis (Ph. D.)--University of California--Los Angeles, 1971. / eContent provider-neutral record in process. Description based on print version record.

This thesis deals with the mathematical idealization denoted cellular automata (CA) and the applicability of this method to structural mechanics. When using CA, all aspects such as space and time are discrete. This discrete nature of CA allows for ease of interaction with digital computers, while physical phenomena which are essentially discrete in nature can be simulated in a realistic way. The application of such a novel numerical method opens up new possibilities in structural analysis. In this study, the fundamentals of CA are studied to determine how the parameters of the method are to be evaluated and applied to the established field of structural analysis. Attention is given to the underlying mathematics of structural mechanics, as well as approximate methods currently used in structural analysis, e.g. the finite element method (FEM) and the boundary element method (BEM). For structural simulations performed with the CA implemented in this study, machine learning based on a genetic algorithm (GA) is used to determine optimum rules for the CA, using finite element, boundary element and analytical approximations as the basis for machine learning. Rather unconventionally, symmetric problems in structural analysis are analyzed using asymmetric rules in the machine learning process, where the symmetry of the solution found is used as a quantitative indication of the quality of the solution. It is demonstrated that the quality of the asymmetric rules is superior to the quality of symmetric rules, even for those problems that are symmetric in nature. Finally, exploiting the inherent parallelism of CA, it is shown that distributed computing can greatly improve the efficiency of the CA simulation, even though the speed-up factor is not necessarily proportional to the number of sub lattices used. The distributed computing device itself is constructed by combining 18 obsolete Pentium computers in a single cluster. In terms of CPU performance the constructed distributed computer is not state-of-art, but it is constructed with no hardware costs whatsoever. In addition, the software used in assembling the cluster is in the public domain, and is also available free of charge. Such a parallel configuration is also known as the poor man’s computer. However, faster and more modern machines can simply be added to the existing cluster as and when they become available. While CA are recent additions to the “tools” used in structural analysis, increased use of CA as distributed computing becomes more widely available is envisaged, even though the CA rules are at this stage not transferable between different problems or even between meshes of varying refinement for a given problem. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

Practice in the field of limit design has tended to place certain restrictions on structural loading patterns in order to simplify the calculations involved in the limit design procedure. The loads considered in this simplified approach are assumed to either remain constant and fixed, or if they vary then this is to be in such a manner that their magnitudes stand in a constant relationship one to the other. Actual structural loadings seldom satisfy these restrictive conditions and the question naturally arises as to whether or not this simplified limit design procedure is valid for general use in practical design problems in which external loads may be wholly independent in their individual actions. This question is investigated in the present paper through the examination of several practical forms of structure which portray the more adverse conditions of independent and variable loading to be met in practice. These structures are, respectively, single and double bay gable bents of lightweight construction, and two forms of multispan bridge girders. The study indicates that all of these structures are able to support the ultimate loads predicted by the simplified limit design method; the actual ultimate loads exceeding the predicted values by up to twenty percent. It is concluded that structural failure in practice can always be expected to occur within acceptable limits of the ultimate load capacity as predicted by the simplified method. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

This thesis presents the results of a theoretical and experimental study of the lateral buckling of two- and three-hinged arches of rectangular cross-section with laterally restrained top edges. The structure is analysed with and without a linear torsional restraint along the top edge. The problem is formulated using the stiffness method. A stiffness matrix including the effects of lateral bending and torsion is used. The buckling load is defined as the smallest load at which the structure stiffness matrix becomes singular. The method of solution of the theoretical lateral buckling is iteration (eigen value problem) and determinant plot. This theoretical approach is verified by model tests with two- and three-hinged parabolic glulam arches in the laboratory. The method of solution for model test is the Southwell plot. The results of the tests are presented and are shown to be satisfactory. A set of numerical results are given for a range of arches with torsional restraint at the top edge and for various load distributions. A sample of calculations of a practical arch shows that, although the arch is safe according to the existing code, it is only safe considering lateral buckling including a torsional restraint at the top edge. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The lateral buckling of two hinged glulam parabolic arches of rectangular cross-section with laterally restrained top edges is investigated. The problem is formulated using the stiffness method. The structure is idealised as a series of straight segments. A stiffness matrix including the effects of lateral bending and torsion is derived and it is shown how the structure stiffness matrix is generated. The buckling load is defined as the smallest load at which the structure stiffness matrix becomes singular. Three methods of solution are given; iteration, determinant plot and Southwell plot. Experimental tests were carried out to check the validity of the theory. The results of the tests are presented and are shown to be satisfactory. A set of numerical results are given for a range of arches and load distributions and a set of design parameters are proposed. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The analysis of structures which contain catenary cables is made difficult by the non-linear force-deformation relationships of the cables. For all but the smallest deflections it is not possible to linearize these relationships without causing significant inaccuracies. Newton's Method solves non-linear equations by solving a succession of linearized problems, the answer converging to the solution of the non-linear problem. Newton's Method so used to analyze cable-containing structures results in a succession of linear stiffness analysis problems. As a result, conventional stiffness analysis computer programs may be modified without great difficulty to solve cable structures by Newton's Method. The use of Newton's Method to solve cable structures forms the body of this thesis. The two basic innovations necessary, which are the provision of methods for calculating the end-forces of a cable in an arbitrary position, and for evaluating the stiffness matrix of a cable, are presented. Also discussed are the co-ordinate transformations necessary to describe the cable stiffness matrix and cable end forces in a Global Co-ordinate System. The virtues of the method are demonstrated in two example problems, and the theoretical basis for Newton's Method is examined. Finally, the value of the method presented is briefly discussed. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate