Behavior of reinforced concrete beam exposed to the effect of temperature

Construction technologies, like all technologies, are constantly evolving. One of the rapidly developing fields of civil engineering is "Repair and strengthening methods". These methods are used when the bearing elements of a structure are damaged or found insufficient. The reinforcement method with carbon fiber reinforced polymers (CFRP) has emerged as an alternative to traditional reinforcement methods. This method is preferred for reasons such as being faster and non-destructive, easy, low structural load, good strength, and corrosion resistant. Past studies clearly reveal to what extent the strength of reinforced concrete members reinforced with CFRP is improved. However, there are not many studies in the literature on external effects that may occur after retrofitting. If a weak structural member is exposed to heat after reinforcement, it is an issue that needs further research on how the performance of the reinforcement will be affected. In this thesis, 24 beam samples belonging to C25/30 concrete class were produced. The dimensions of the samples are 10x15x48 cm. Half of the samples were wrapped with CFRP. The other half was left unwrapped. The samples in both groups were stored at 24 °C, 120 °C and 240 °C for two hours. The bending strengths of the samples before and after heat exposure were tested. The results of the study showed that the samples wrapped with carbon fiber fabric gained about 15% strength at ambient temperature compared to the unwrapped samples. There was no significant loss of strength in the samples heated up to 120 °C. On the other hand, about 8% strength loss was detected in the strengthened samples exposed to 240 °C heat.