Study on Thermal Stress of Concrete Beams with Carbon-Fiber- Reinforced Polymers at Low Temperature

Concrete beams reinforced with carbon-fiber-reinforced polymers (CFRPs) are subjected to considerable thermal stress at low temperatures. To mitigate this problem, this study conducts a series of tests on three concrete specimens at various temperatures, analyzes the change rule of thermal stress in CFRP-reinforced concrete beams, and discusses the influence of CFRPs on thermal stress in terms of the elastic modulus, thickness, thermal expansion coefficient, beam height, and concrete grade. The results show that when the temperature decreases, CFRP has an obvious restraining effect on the thermal curve of concrete beams. The thermal stress on the interface of CFRP-reinforced concrete beams is sufficiently large and should not be ignored. In particular, in cold areas, thermal stress should be taken into account when reinforcing structures such as concrete bridges. The CFRP sheet’s elasticity modulus and thickness are the main factors affecting the thermal stress; in comparison, the expansion coefficient and beam height have lesser effect on the thermal stress; finally, the concrete grade has little effect on the thermal stress. Thermal stress can be prevented feasibly by using prestressed CFRP sheets to reinforce concrete beams. This study can serve as a reference for concrete reinforcement design.