Experimental study on fire performance of CFRP-strengthened reinforced concrete beams with different protection schemes

Abstract:

The reinforced concrete (RC) components strengthened with carbon fiber-reinforced polymer (CFRP) without fire protection measures are difficult to meet the standard requirements of fire resistance rating due to the flammability of CFRP. To study the fire performance of CFRP-strengthened RC beams based on the previous studies, nine RC beams with the same geometry and steel reinforcement were prepared with different strengthening methods and fire insulation schemes and tested under the ISO 834 standard fire. The test variables included various anchorage systems for externally bonded (EB) CFRP sheets (no anchorage, mechanical anchorage and U-wrap CFRP sheets), different fire insulation materials (intumescent fire-retardant coatings, cement-based fire protection mortar and cement mortar) and different thicknesses of fire insulation layers for different zones along the span direction. The temperature distributions and the deflection responses of these specimens under fire exposure were recorded and compared. It has demonstrated under this test condition that: U-wrap CFRP sheets used as the anchorage system are more efficient in limiting the deflection responses compared to the mechanical anchorage system; the combined use of the intumescent fire-retardant coatings and the cement mortar is practicable to protect the specimen from fire damage; the fire insulation provided by the 20 mm cement mortar and 2 mm intumescent fire-retardant coatings is better than that of 20 mm thick fire protection mortar.