Turkowski Piotr
Instytut Techniki Budowlanej, Filtrowa 1, 00-611 Warszawa, Poland.
Materials (Basel). 2023 Jul 25;16(15):5234. doi: 10.3390/ma16155234.
The fire resistance of reinforced concrete (RC) beams strengthened with externally bonded reinforcement carbon fibre-reinforced polymers (EBR CFRP) depends on the load level and degree of strengthening. Design guides for this type of structure recommend strengthening limits to prevent collapse of the structure due to vandalism, damage or fire. In practice, however, it is not uncommon to exceed the proposed limits. This necessitates protection of the CFRP adhesive against high temperatures, namely glass transition temperature levels. This paper presents the results of 10 full-scale experimental fire resistance tests of reinforced concrete beams with EBR CFRP strengthening, with and without fire protection and under various load levels including full utilisation. It was demonstrated that in cases where CFRP strengthening was not needed to carry load in an accidental fire scenario, test specimens with and without it achieved the same fire resistance. It was also proven that in cases where CFRP failure influenced the failure of the entire beam, fire protection was crucial for maintaining the beam's load-bearing capacity and its thickness had to be substantial. A fire resistance rating of over 4 h was achieved, nevertheless.
采用外部粘结增强碳纤维增强聚合物（EBR CFRP）加固的钢筋混凝土（RC）梁的耐火性取决于荷载水平和加固程度。这类结构的设计指南建议设置加固限制，以防止结构因故意破坏、损坏或火灾而坍塌。然而在实际中，超过建议限制的情况并不少见。这就需要保护CFRP胶粘剂免受高温影响，即玻璃化转变温度水平的影响。本文介绍了10个采用EBR CFRP加固的钢筋混凝土梁的全尺寸耐火试验结果，这些试验梁有防火保护和无防火保护，且处于包括满载使用在内的各种荷载水平下。结果表明，在意外火灾场景中不需要CFRP加固来承载荷载的情况下，有CFRP加固和无CFRP加固的试件具有相同的耐火性。还证明了在CFRP失效影响整个梁的失效的情况下，防火保护对于维持梁的承载能力至关重要，且其厚度必须足够大。不过，仍实现了超过4小时的耐火等级。
