Fire behaviour of vacuum-infused glass fibre reinforced polymer sandwich panels: The role of polyurethane and polyethylene terephthalate foam cores and panel architecture

This paper presents an experimental investigation about the fire behaviour of sandwich panels composed of glass fibre reinforced polymer (GFRP) face sheets and longitudinal webs produced by vacuum infusion. The experimental programme comprised eleven fire resistance tests on simply supported GFRP sandwich panels, exposed to the ISO 834 standard fire and loaded in bending under a sustained service load. The influence of using different core materials – polyurethane (PUR) and polyethylene terephthalate (PET) foams – and the presence of longitudinal GFRP webs with different configurations was investigated. The efficacy of two passive fire protection systems was also evaluated, namely calcium silicate (CS) boards adherent on the bottom face sheet of the GFRP panels or suspended from it forming an air cavity. The web-core sandwich panels presented longer fire resistance compared to the homogenous-core ones ( i.e. ¸ without webs), due to the improved shear performance provided by the longitudinal GFRP webs. Furthermore, the adoption of passive fire protection remarkably extended the fire endurance of the sandwich panels by delaying the thermal degradation of their constituent materials: the time to collapse of the panels protected with adherent CS boards ranged from 40 to 67 min, depending on the type of core materials used and presence of GFRP webs, while that of the panel reinforced with longitudinal webs and protected with suspended CS boards was around 90 min. • GFRP sandwich panels exposed to fire under out-of-plane loading. • PET/PUR foams led to similar collapse times, but different thermomechanical behaviour. • Web-core panels showed improved fire resistance due to enhanced shear performance. • Passive fire protection significantly increased fire endurance of the panels. • Suspended CS boards provided up to 90 min fire resistance in web-core panels.