The application of orthotropic plate theory to decking systems

The purpose of the work presented in this thesis was to examine the applicability of orthotropic plate theory to the behaviour of corrugated decking under lateral loading, and to pursue parallel to the theoretical work an appropriate experimental investigation. A review of the relevant published literature is given in Chapter I. The development of orthotropic plate theory and its application to engineering problems is outlined and it is noted that much of the theoretical work of the past has been limited due to the difficulty of adequately defining the convergence of the assumed series solutions. Further, this difficulty has inhibited the development of solutions of a general nature defining all possible variations of the elastic stiffnesses for a given plate shape. It is further indicated that while there has been a great deal of interest shown in the experimental evaluation of the appropriate plate moduli and stiffnesses, little work has been carried out in applying the results of these tests to the behaviour of orthotropic plates under different loading and boundary conditions. The theoretical work of Chapter II opens with a brief outline of the derivation of the governing equations for the elastic behaviour of an orthotropic plate. The orthotropic plate compatibility equation and consistent boundary conditions are then derived and the author's solution to the problem of the bending of an orthotropic plate under uniform transverse loading is given. A complete investigation of the two major modes of solution is given and the plate behaviour for various combinations of stiffness ratios presented. The chapter closes with an outline of a method devised by the author for the assessment of the anticlastic surface exhibited by an orthotropic strip when bent by a pure moment. This analysis is used to justify the experimental evaluation of the principal stiffness of a plate by a simple bend test and the use of the reciprocal relationships in orthotropic plates. Chapter III describes the experimental techniques developed to measure the plate stiffnesses and also the apparatus built to test and measure the behaviour of deciding specimens under a uniformly distributed load. The results of the experimental deflection and strain investigations are compared with the the theoretical values in Chapter IV and good agreement is shown to obtain. The design aspects of light gauge metal decking are discussed in Chapter V and this section demonstrates the utility of the strut compression test in estimating that stress at which elastic buckling in a light gauge metal deck under uniform lateral load is initiated. An experimental investigation undertaken to substantiate the above statement is detailed and the chapter closes with the substantiation of a simplified collapse load concept to provide the basis for design. Chapter VI summarises the main findings of the theoretical and experimental work and Chapter VII contains a full bibliography and author index. The thesis concludes with six appendices which enlarge on various aspects of the analysis and also present the detailed results of the experimental investigations