Experimental study on dynamic mechanical properties of carbon fiber reinforced polymer ( <scp>CFRP)</scp> ‐reinforced concrete beams based on rate correlation

Abstract The dynamic mechanical behavior of concrete has an obvious rate correlation, for this reason, the three‐point bending experiments were carried out on carbon fiber reinforced polymer (CFRP)‐reinforced concrete beam specimens under three different loading rates (0.1, 0.01, 0.001 mm/s). The effects of different loading rates on the damage process, load‐crack mouth opening displacement ( P ‐ CMOD ) curves, and fracture toughness of CFRP‐reinforced concrete beams were investigated by displacement‐controlled monotonic loading. In addition, acoustic emission (AE) and digital image correlation (DIC) techniques were used to monitor and analyze the fracture process of CFRP‐reinforced concrete beams under different loading rates. The experiment results show that, the initiation load, instability load, and fracture toughness of CFRP‐reinforced concrete beams increase with the increase of loading rate. There is a logarithmic function relationship between the fracture toughness of CFRP‐reinforced concrete beam and the loading rate. Based on the P ‐ CMOD curves and AE ringing count, the fracture failure process of CFRP‐reinforced concrete beam can be divided into five stages. The FPZ of the instability load point of CFRP‐reinforced concrete beam can be determined by DIC technology, and the logarithm of the loading rate ratio is quadratic correlated with the length of FPZ. With the increase of loading rate, the length of the FPZ decreases, the percentage of AE signals in the FPZ decreases.