GFRP–concrete hybrid cross-sections for floors of buildings

The development of flooring systems with improved durability and higher speed of construction has, in recent years, led to the study of new structural solutions. This paper presents the results of a study of an innovative solution for floors of buildings, with glass fibre reinforced polymer (GFRP) pultruded profiles connected to concrete elements, with either steel bolts or an epoxy adhesive layer. Shear connection tests were first conducted on GFRP I-profiles connected to concrete, using both shear connection systems. The results of those tests were then used to design simply supported beams with a GFRP–concrete hybrid cross-section, which were tested in bending with different spans and load arrangements, comprising two alternative shear connection systems. The experimental programme included also investigations on the strength of different configurations of supports of hybrid beams. In order to better understand some of the experimental results, namely the debonding mechanisms observed at the interface of hybrid beams with bonded shear connection systems, numerical analyses were performed to investigate the stress state at the interfaces. Experimental and numerical investigations showed the viability of using GFRP–concrete hybrid cross-sections in floors of buildings, either for rehabilitation or for new constructions, and proved that adequate constructive detailing can significantly improve the performance of the proposed system.