Axial Stress-Strain Model of CFRP-Confined Concrete under Monotonic and Cyclic Loading

Experimental results of the axial stress-strain response of eighteen carbon-fiber-reinforced polymer (CFRP) confined circular, square, and rectangular column specimens when subjected to cyclic axial compression are presented and discussed. Guided by these test results and other test data reported in the technical literature, a constitutive axial stress-strain material model of CFRP-confined concrete under generalized loading is developed. The proposed model, which is composed of a monotonic envelope response and a cyclic response, accounts for a wide range of test parameters and assumes a more simplified approach than existing models available in the literature. The model covers all important parameters in a unified manner, and predicts both ascending and descending postpeak responses. In addition to its simplicity in application, despite little discrepancy, the model was able to reproduce the test results generated in the experimental part of this investigation and other test data reported in the technical literature with good accuracy. The model can be incorporated in numerical analysis schemes for predicting the cyclic response of CFRP-confined concrete structural members. (C) 2015 American Society of Civil Engineers.