Abstract
The civil engineering industry is constantly striving for ways to improve design and construction technologies to obtain more efficient solutions to engineering problems. It has long been recognised that, in the area of construction utilising reinforced concrete beams, the region of the beam below the neutral axis (NA) is wasteful of material. The only function that the low tensile strength concrete has in this situation is to locate the steel rebars and protect them from aggressive environments. It is proposed in this investigation that the zone of a beam below the NA is removed and replaced by an advanced polymer composite (APC) material ideally suited for civil construction. This Thesis presents a detailed investigation into a number of 1.5 m span ‘hybrid’ T-beams which utilise concrete in the compressive region of the beam and APC materials in the tensile region. Two designs for T-beam have been analysed; one in which the failure mode is by buckling of the web and one by a shear failure in the bond along the interface between the concrete and permanent APC shuttering. The study includes variations in these two designs incorporating different methods of stiffening the web and confining the top surface of the concrete. The effects on the mechanical properties of these materials when exposed to water, salt solution, UV radiation, temperature and a solution simulating the fluid state in the pores of wet concrete were analysed. The test results have indicated that the failure mode for this type of design is buckling of the webs followed by concrete crushing and buckling of the permanent GFRP shuttering. Confining the concrete produced a beam with a more ductile response and the long-term effects of the beam were shown to be dependent on the properties of the concrete. The beams' structural behaviour was adequately predicted by numerical analysis techniques.