Carbon fiber-reinforced polymers (CFRP) have been widely used for retrofitting and strength-ening concrete structures over the past two decades. Concrete members strengthened by exter-nally bonded CFRP sheets can fail prematurely in debonding between the interface of CFRP and concrete, not allowing full utilization of CFRP tensile strength. The objective is to study the effect of changing the width and thickness of the CFRP anchorage patches on the tensile strength and effective strain of the FRP reinforcement sheets under the same strengthening con-ditions.
There are seven specimens were conducted in this test. The parameters for anchor patches are anchor patches with a width of 50 and 75 cm, and anchor patches with a thickness of 2 and 4 plies. For the CFRP anchor patch performance test, taking the specimen number PA1 as an ex-ample, the size of the concrete block is 1600×850×354 mm and the size of the CFRP anchor patch is 1500×500 mm. The patch anchor performance test results show that the maximum av-erage strain of PA1 was 0.0038 and the maximum tensile force of PA1 was 138.57 kN.
The results indicated that (1) when the CFRP patch anchorage method is used in the reinforcing scheme, the effective strain of the CFRP reinforcement sheets under the maximum tensile force is above 0.0038. (2) The CFRP patch anchorage method improves the tensile strength and ef-fective strain of the CFRP reinforcement sheets, and increasing the width of the CFRP anchor-age patch increases the tensile strength and effective strain of the CFRP reinforcement sheets. (3) As the CFRP reinforcement sheets are 4 layers, the best matching and performance for CFRP anchor patches are 2 layers. (4) The Equation 1 overestimates the ultimate bond strength, it is recommended that reduction factor = 0.55 be conservatively used for correction.