Abstract
For the past two decades the suitability of fibre reinforced composite components for use in structural engineering is being realised. As composite materials have a low specific weight and excellent durability characteristics they have now become an attractive alternative to conventional construction materials. Although general acceptance of composites in structural engineering will take time, considerable advances in research and development of these materials are and have been achieved worldwide. A major development in advanced composite technology in recent years has been the refinement of the pultrusion manufacturing technique enabling the production of a variety of high quality structurally efficient composite components to be made for use in the construction industry. This thesis will analyse and compare the experimental, analytical and numerical behaviour of composite structures which are manufactured from an advanced fibre reinforced pultruded interlocking cellular component. As composite materials are anisotropic in character their mechanical properties are fundamentally different from conventional construction materials. Analytical macro and micro mechanical theories available for the design of composite materials tend to be empirical and therefore are not capable of predicting the exact mechanical response of the composite material in a given pultruded component. As a consequence experimental testing of the advanced composite material is the only reliable method of determining the mechanical behaviour of components made from it. In the current work coupon samples of the pultruded composite material were cut, at off-axis angles of 0°, 45° and 90°, from the anisotropic component and were then subjected to a series of experimental tests to characterise their mechanical behaviour. These tests investigated the short term static, the short term thermal, the long term thermal, the fatigue, the durability, the hygrothermal and the failure criteria of the composite material. Analytical equations representing the mechanical behaviour of the composite material were developed using the results of the experimental tests performed and other published research. Generally the developed equations were shown to represent accurately the experimental response obtained from the composite material coupons. The finite element technique was used to model the complex geometry of the pultruded components but the current capabilities of this technique are not able to model the nonlinear anisotropic behaviour of composite materials. Consequently a numerical tensor representing the mechanical behaviour of the composite material was developed and this was then interfaced with a finite element package. This tensor, which is general in format, can be used to represent the mechanical response of any composite material in a finite element analysis provided a series of experimental tests has been performed on the composite material. To verify the numerical technique which was developed for structural composites, prototype pultruded composite bridge superstructures were tested experimentally under incremental loading to failure, concentrated local loads, transient loads, dynamic, buckling and fatigue loads. The experimental test results compare well with those obtained from identical numerical models of the prototypes.