Probabilistic design models for ultimate strength and strain of FRP-confined concrete

This paper presents a probabilistic procedure for deriving design models for the ultimate strength and strain of fiber–reinforced-polymer (FRP)-confined concrete. First, a large database of axial compression tests performed on circular FRP-confined concrete specimens is collected for calibrating an ultimate strength model, based on the Drucker-Prager criterion, and an ultimate strain model, based on the ultimate dilation rate. The database is also employed for deriving a probabilistic model for the FRP strain efficiency factor. The calibrated models, though simple, show superior performance over some of the models in the literature. Then, using the Central Limit Theorem and considering uncertainty in the mechanical properties of the concrete and FRP material as well as their correlation, analytical probabilistic design models for the ultimate strength and strain of FRP-confined concrete are derived. These models can be used in the design and reliability analysis of FRP-confined columns.