Experimental study on the flexural behaviour of multi-span transparent glass–GFRP composite beams

In recent years there have been an increasing number of applications of glass in civil engineering structural members, such as roofs, floors, beams and columns. Such interest stems basically from the aesthetical possibilities of glass, in particular its transparency. However, glass presents several limitations, including relatively low tensile strength and brittle behaviour, which contrasts with current design philosophies associated with more conventional materials, such as steel and reinforced concrete. One of the possibilities of overcoming these disadvantages is joining reinforcing materials to glass. The main goal of those transparent composite structural solutions is to increase the post-cracking residual strength and ductility of glass beams. This paper presents results of an experimental study about the flexural behaviour of multi-span composite beams made of annealed glass panes reinforced with GFRP pultruded laminates. The main goal of this study was to evaluate the post-cracking behaviour of such continuous beams, namely the influence of the adhesive used in their construction. The experimental programme included (i) material characterization tests, (ii) tensile tests on double lap joints between glass and GFRP pultruded laminates, bonded with different structural adhesives, and (iii) full-scale flexural tests on multi-span glass–GFRP composite beams, with interfaces bonded also with different adhesives. Results showed that multi-span glass–GFRP composite beams are able to exhibit significant post-cracking residual strength and ductility, stemming not only from their cross-sectional redundancy but also from their capacity to redistribute internal forces. The ultimate load and the post-cracking performance of the multi-span composite beams are significantly affected by the type of the adhesive used to bond GFRP to glass.