Abstract
This thesis is an investigation into the use of plastics in structures of the folded plate type. Plastics as a structural material has first been critically evaluated with particular reference to the types that may be used for structural purposes. The differences in the mechanical properties between these materials and conventional materials have been examined in detail. Conventional design concepts have been suitably enlarged to take these differences into account. Folded plate structures in plastics built up from prefabricated units have then been examined. The two-plate unit enables the complete prefabrication of a variety of structures, particularly of the composite type, and has been selected for further study. The existing approach to the analysis of folded plates has been modified for application to such structures in plastics. This modified approach is particularly suitable for use with composite folded plate structures formed from non-prismatic plates. Large transverse deflections of the structure can be conveniently taken into account. This modified approach has been verified by experimental work on the roof structure, the two-pinned composite folded plate portal frame and a composite folded plate barrel vault. Folded plate structures in plastics can be of single skin or sandwich construction. The properties of expanded polystyrene and rigid polyurethane foam for use as low density cores in such sandwich construction have been determined. A prototype composite folded plate barrel vault of sandwich construction has been developed and tested. Special attention has been paid to the connections between the fully prefabricated units. The costs of the structure have been briefly examined. The test results have been analysed and the theoretical and experimental behaviour of the structure have been compared. Final conclusions have been drawn and suggestions for further research have been made.