Flexural behaviour of GFRP–concrete hybrid beams with interconnection slip

The design of glass fibre reinforced polymer (GFRP) pultruded beams is usually governed by deformability or instability phenomena. To obtain a better use of the material properties, the GFRP profiles can be connected to concrete elements with several advantages, associated with the global stiffness and strength of the structural elements. This leads to solutions particularly useful for rehabilitation of old floors or even new construction slabs. This paper presents the results of an experimental research developed to characterize the flexural behaviour of a GFRP–concrete hybrid solution. Shear connection tests were first performed on GFRP I-profiles, connected to concrete with stainless steel bolts, to evaluate the behaviour of the shear connection. The results of those tests were then used to design simply supported GFRP–concrete hybrid beams that were tested under bending conditions. The flexural behaviour of the GFRP–concrete hybrid beams is discussed, with particular relevance to the effect of the interconnection slip. The overall behaviour of the hybrid beams is compared with that corresponding to a simple GFRP I-profile beam, demonstrating the structural advantages of this new hybrid constructive solution.