Abstract
The research described has been undertaken in an attempt to give an answer to questions often asked: Can glass fibre reinforced plastics be used as a structural material? Can a structure in GRP compete with conventional materials? The relatively high cost of moulds needed for plastic structures prevents many projects from ever leaving the drawing board. In order to overcome this drawback a special "cocooning" technique was developed which provides low cost moulds for highly warped anticlastic surfaces. Moulds were produced by this process for the manufacture of the GRP elements used in the experimental work. It is due to the successful development of the process in the course of the research that the investigation was able to deal with an extensive number of configurations. The research work is presented in three main parts: (a) An outline of the material characteristics, with particular reference to polyester resin reinforced with chopped strand mat. (b) An extensive study of the morphology of hyperbolic paraboloid surfaces, illustrated with the aid of numerous models and drawings. (c) An experimental method of analysis for a scalloped dome, made as a single skin GRP laminate. In order to study in more detail the behaviour of hyperbolic paraboloid shells in GRP a large model was constructed. The model had a clear span of 4 metres (13-123 ft.) and consisted of 26 hyperbolic paraboloid segments having an average shell thickness of 3 millimetres (0.1l8 in.). Gravity loads were hung from 1,352 points to simulate various types of live loading. Strain measurements were taken by means of electric resistance strain gauges. The tests on the scalloped dome demonstrated its great rigidity against buckling and showed that it is possible to build structures of this type with an average thickness of shell to span ratio of 1:1,500.