This work is concerned with both static and dynamic behaviour of elastic plate systems. It is restricted to a particular, but important, class of structure made up of a series of thin, flat rectangular plates connected together along their longitudinal edges, and simply supported along their ends. The study is subdivided into three parts dealing, respectively, with the following aspects of the topic: (i) theoretical static analysis; (ii) theoretical dynamic analysis; (iii) experimental dynamic identification. For the static analysis of plate systems, of open or closed cross-section, a number of procedures are developed as extensions of the matrix progression technique. The proposed methods are exact in the sense that they are derived from elasticity theory and are highly efficient, especially for cross-sections of simple-chain configuration. They are more versatile than previous elasticity methods for plate systems in that they are applicable to orthotropic as well as isotropic plates, carrying distributed as well as concentrated loadings. . A new composite formulation is then presented for the free vibration analysis of plate systems. In this method an exact static stiffness matrix for orthotropic plates is used in conjunction with a consistent mass matrix adapted from finite strip theory, to give a linear eigenvalue problem which may be solved by standard routines. Special attention is directed to flexural vibration in the presence of in-plane forces, and to the vibration of systems with attached concentrated masses. The effect on accuracy of dynamic condensation techniques is also investigated. In the experimental study a statistical procedure, utilising pseudo-random test signals and cross-correlation analysis, is applied

The analysis and dynamic identification of plate systems

A METHOD OF ANALYSIS OF BOX-GIRDER AND MULTICELLULAR BRIDGE DECKS IS PROPOSED. ALTHOUGH SIMILAR TO THE DIRECT STIFFNESS TECHNIQUE, IT INCORPORATES THE MATRIX PROGRESSION CONCEPT FOR OBTAINING THE STIFFNESS MATRICES FOR THE INDIVIDUAL PLATE ELEMENTS: RESULTS FROM EXPERIMENTS WITH TWO PERSPEX MODELS ARE SHOWN TO AGREE SATISFACTORILY WITH THEORETICAL CALCULATIONS. THE METHOD OF ANALYSIS IS SYSTEMATIC AND CONVENIENT FOR COMPUTATION. COMPUTER STORE REQUIRED FOR A MULTI-CELL BOX IS SMALL COMPARED TO OTHER NUMERICAL METHODS SINCE THE PLATES BETWEEN JUNCTIONS CAN BE CONSIDERED AS INDIVIDUAL ELEMENTS AND FURTHER SUBDIVISIONS ARE UNECESSARY. CONVERGENCE OF THE MOMENTS AND FORCE QUANTITIES IS SLOWER THAN THAT OF THE DISPLACEMENTS. HOWEVER, FOR THE EXAMPLES CITED SUMMATION OF 19 HARMONICS WAS CONSIDERED TO BE SUFFICIENT. THE GENERAL FLEXIBILITY OF THE METHOD MAKES IT POSSIBLE TO REPRESENT PRECISELY ANY LOAD CONDITION, WHETHER IT IS NORMAL OR IN-PLANE, BY USING SUITABLE FOURIER REPRESENTATION. ADDITIONAL FORCES APPLIED THROUGH PRESTRESSING CAN ALSO BE INCORPORATED IN THE LOAD VECTOR WHEN DIVIDED INTO CORRESPONDING COMPONENTS IN THE VERTICAL AND HORIZONTAL DIRECTIONS. THE PROBLEM OF INTERMEDIATE SUPPORTS CAN BE ANALYZED USING AN INFLUENCE TECHNIQUE IN WHICH THE INTERNAL REACTIONS ARE FIRST CALCULATED FROM THE CONDITIONS THAT THE RESULTANT DEFLECTIONS AT THE SUPPORTED POINTS ARE ZERO. THE FINAL SOLUTION IS THAT OF A SINGLE-SPAN STRUCTURE UNDER THE COMBINED ACTION OF THE APPLIED LOAD AND THE REACTIONS. THE ADVANTAGE OF THE METHOD IS ITS APPLICABILITY TO ELEMENTS OTHER THAN THE ISOTROPIC RECTANGULAR PLATE ELEMENTS. A SMALL CHANGE OF THE GOVERNING MATRICES CAN MAKE THE SOLUTION SUITABLE FOR ORTHOTROPIC RIGHT OR FAN-SHAPED PLATES. FURTHERMORE THE STIFFNESS MATRIX FOR A SHELL ELEMENT CAN BE OBTAINED BY USING THE SAME MATRIX PROGRESSION TECHNIQUE. THESE EXTENSIONS ARE LIKELY TO MAKE THIS METHOD SUITABLE FOR A NUMBER OF COMPLEX BRANCH PLATE PROBLEMS INCLUDING THE RIGHT OR CURVED BOX-TYPE BRIDGE DECKS. /TRRL/

P C Das

Papers

Analysis of box-type structures.