Experimental investigation of size effect on mechanical properties of carbon fiber reinforced polymer (CFRP) confined concrete circular specimens

The mechanical properties of concrete have significant size effect. Size effect of carbon fiber reinforced polymer (CFRP) confined concrete specimens should be investigated further. In this study, the uniaxial compressive tests of CFRP confined concrete cylinders in different sizes (70 mm, 100 mm, 150 mm, 190 mm, 310 mm) under different confinement (CFRP of one layer, two layers and three layers) were conducted. Four parameters were obtained, including interception strength, uniaxial compressive strength, strain of turning point and peak strain. From the test results, it can be found that the uniaxial compressive strength of unconfined concrete cylinders has apparent size effect which accords with the Weibull size effect law. Under different ratios of CFRP confinement, the CFRP confined concrete cylinders have apparent size effect. The stress-strain model proposed by Lam and Teng fails to interpret how size effect acts on the mechanical properties of specimens. Thus, based on the stress-strain model proposed by Lam and Teng, a modified stress-strain model with the consideration of size effect was established.