Thermo-mechanical performance of Carbon Fiber Reinforced Polymer (CFRP), with and without fire protection material, under combined elevated temperature and mechanical loading conditions

In civil engineering, when a CFRP-reinforced structure is subjected to fire, both the structure and CFRP are simultaneously affected by elevated temperature and mechanical loading. In the Eurocodes, the strengths of concrete and steel are described to be reduced with increased temperature; however, the codes do not describe the performance of hand-laid CFRP. This paper presents the thermomechanical performance of hand-laid CFRP with and without thermal insulation under different mechanical loading conditions. Experimental tests were conducted to identify the maximum transient heating temperature and duration to which CFRP can be exposed at different levels of mechanical load. The results show that when the applied load increases, the rupture temperature and maximum exposure duration decrease. At 20 °C, the rupture temperature of CFRP gradually decreases when the applied load increases from 10% to 50% of the material's ultimate strength; at room temperature, as the applied load reaches 75% of the ultimate strength, the rupture temperature significantly decreases. Likewise, the exposure duration gradually decreases when the applied load varies from 10% to 50% of CFRP's ultimate strength, and decreases considerably when the applied load is 75% of the ultimate strength. Additional tests were conducted on CFRP protected by an insulation material to characterize the effectiveness of the used insulation material used on the performance of hand-laid CFRP subjected to thermal and mechanical loading. Finite element models were used to investigate the thermal conduction, and these models were successfully validated by the experimental results. Thus, the models were confirmed to predict the fire protection capability of the used insulation material reliably and accurately.