New mechanics-based confinement model and stress–strain relationship for analysis and design of concrete columns wrapped with FRP composites

Abstract

The analysis and design of concrete columns wrapped with fiber-reinforced polymer (FRP) composites require the mathematical equation of stress–strain relationship and the ultimate conditions (i.e., stress and strain) corresponding to the failure of FRP-confined concrete. The ultimate conditions of FRP-confined concrete were mostly developed using empirical methods based on regression analysis of test data obtained from the literature. There is a lack of mechanics-based formulations of the ultimate condition. In addition, from a practical design perspective, despite new advancements in the field of FRP confinement and the availability of sophisticated analysis-oriented and data-driven models, design guidelines and practicing engineers mainly need a single equation for the stress–strain relationship of confined concrete. Thus, in this study, a five-parameter William-Warnke plasticity model was utilized to find a new mechanics-based prediction of the ultimate condition of FRP-confined concrete using an updated database of 788 test data. Moreover, a new optimized stress–strain relationship based on the general expression of the Richard and Abbott equation was developed using 200 complete experimental stress–strain curves from 16 different independent studies. The proposed stress–strain relationship was presented in a single equation for the ease of application and its performance was verified against the experimental curves.