Unified model for evaluating ultimate strain of FRP confined concrete based on energy method

An energy balance approach is adopted to develop the model for calculating the ultimate strain of fiber reinforced polymer (FRP) confined concrete columns in this work. The proposed model can be used to predict the ultimate strain of columns under both concentric and eccentric loading. In the meantime, it makes use of a unified form so that it can be applied to different shapes of columns. A database that includes a large number of updated test results is used to evaluate the model parameters and coefficients. Compared with other existing models reported in extant literature, the proposed model exhibits a better performance.