Design-oriented stress-strain model for concrete prisms confined with FRP composites

A good modeling of the stress-strain behavior of FRP-confined concrete prism is necessary for the design of rectangular columns retrofitted with FRP composites. Existing stress-strain models for FRP-confined concrete prisms are mostly presented based on the concept of steel-confined concrete columns. Based on the results of more than one hundred specimens, the mechanical behavior of FRP-confined concrete prisms are studied in this paper. It is found that the stress-strain relationship of FRP-confined prism has either a strain-hardening or a strain-softening response, which mainly depends on the confinement strength of FRP, corner radius of cross-section, etc. Equations to predict the transitional stress and strain of FRP-confined concrete prisms are presented. By reducing the corresponding ultimate strength and strain of equivalent concrete cylinders confined with equivalent FRP, the ultimate strength and strain of FRP-confined concrete prisms can be predicted rationally. Three design-oriented models, which can be applied to various conditions, are suggested. The feature of those models is simple, and they agree well with extensive experimental results. (c) 2006 Elsevier Ltd. All rights reserved.