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Evaluation on the Bond Capacity of the Fire-Protected FRP Bonded to Concrete Under High Temperature
International Journal of Concrete Structures and Materials ( IF 3.6 ) Pub Date : 2021-01-27 , DOI: 10.1186/s40069-020-00448-3
Soo-yeon Seo , Jong-wook Lim , Su-hyun Jeong

To figure out the change in the reinforcing effect of FRP system used for the retrofit of RC beam when it is exposed to high temperature, it is required to evaluate not only the behavior of the entire beam, but also the bond performance at anchorage zone through a bond test according to the increase of external temperature. Moreover, the study to find various fire-protection methods is necessary to prevent the epoxy from reaching the critical temperature during an exposure to high temperature. In this manner, the fire-resistance performances of externally bonded (EB) FRP and near-surface-mounted (NSM) FRP to concrete block were evaluated by high-temperature exposure tests after performing a fire-protection on the surface in this paper. Board-type insulation with mortar was considered for the fire-protection of FRP system. After the fire-protection of the FRPs bonded to concrete blocks, an increasing exposure temperature was applied to the specimens with keeping a constant shear bond stress between concrete and the FRP. Based on the result, the temperature when the bond strength of the FRP disappears was evaluated. In addition, a finite element analysis was performed to find a proper method for predicting the temperature variation of the epoxy which is fire-protected with board-type insulation during the increase of external temperature. As a result of the test, despite the same fire-protection, NSM specimens were able to resist 1.54–2.08 times higher temperature than EB specimens. In the design of fire-protection of FRP system with the board-type insulation, it is necessary to consider the transfer from sides as well as the face with FRP. If there is no insulation of FP boards on the sides, the epoxy easily reaches its critical temperature by the heat penetrated to the sides, and increasing the thickness of the FP board alone for the face with FRP does not increase the fire-resistance capacity. As a result of the FE analysis, the temperature variation at epoxy can be predicted using the analytical approach with the proper thermal properties of FP mortar and board.



中文翻译:

耐高温FRP粘结到混凝土的粘结能力评估

为了弄清楚用于钢筋混凝土梁的FRP系统在高温下的加固效果的变化,不仅需要评估整个梁的性能,而且还需要评估其在锚固区域的粘结性能。根据外部温度的升高进行键合测试。此外,寻找各种防火方法的研究对于防止环氧树脂在暴露于高温下达到临界温度是必要的。通过这种方式,在对表面进行防火之后,通过高温暴露测试评估了外部粘结(EB)FRP和近表面贴装(NSM)FRP对混凝土砌块的防火性能。考虑使用砂浆板式隔热材料来防火FRP系统。在对粘结到混凝土砌块的FRP进行防火保护后,在保持混凝土与FRP之间恒定的剪切粘结应力的情况下,将不断升高的暴露温度施加到试样上。基于该结果,评价了FRP的粘结强度消失时的温度。此外,进行了有限元分析,以找到预测外部温度升高期间用板型绝缘防火的环氧树脂的温度变化的合适方法。测试的结果是,尽管具有相同的防火保护,但NSM标本的耐高温性是EB标本的1.54–2.08倍。在使用板状绝缘材料的FRP系统防火设计中,必须考虑FRP从侧面和表面的转移。如果在侧面没有FP板的绝缘层,则环氧树脂容易通过渗透到侧面的热量达到其临界温度,并且仅增加FP板的厚度(对于FRP的工作面)不会增加耐火能力。作为有限元分析的结果,可以使用具有FP砂浆和木板适当的热性能的分析方法来预测环氧树脂的温度变化。

更新日期:2021-01-28
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