Effect of fibre orientation and thermal exposure on the post-fire mechanical behaviour of carbon fibre reinforced polymer material

This study investigates the influence of fibre orientation and heat flux on the post-fire (residual) load-bearing properties of carbon fibre-reinforced polymer (CFRP) laminates. As a result, a deep insight into the post-fire load-bearing response is gained, which is necessary to fully understand and assess the advantages of CFRP laminates containing different fibre orientations for use in load-bearing structures. Specimens were produced from three CFRP laminates containing different fibre orientations, exposed to varying heat fluxes up to 40 $\mathrm{kW}/m^2$ and then loaded in either tension or three-point bending at ambient room temperature. The study's results have shown that the post-fire behaviour of CFRP specimens is sensitive to changes in fibre orientation and heat flux. For example, specimens with an anisotropic fibre orientation in tension had the highest tensile load-bearing capacity, whereas those with bidirectional and multi-directional fibre orientations demonstrated lower tensile load-bearing capacities. In bending, however, specimens containing bidirectional and multidirectional fibre orientations had higher load-bearing capacities than specimens with an anisotropic fibre orientation. Furthermore, the data also shows that exposure to a heat flux reduces the load-bearing capacity in both the bending and tensile specimens.