Analytical Model for FRP-and-Steel-Confined Circular Concrete Columns in Compression

Abstract

Providing additional confinement by external fiber-reinforced polymer (FRP) wrapping is one of the most common and effective techniques for the retrofit of existing reinforced concrete columns. Over the past 2 decades, researchers have made much progress on the development of constitutive models to describe the behavior of FRP-confined circular concrete sections in compression. However, only recently have a few models been published representing the first attempts to develop a constitutive model for circular concrete columns in compression confined by both external FRP wraps and internal transverse steel. A critical review and evaluation of existing FRP-and-steel-confined concrete constitutive models highlights the need for a more robust model. This paper presents the development of a new FRP-and-steel-confined concrete in compression constitutive model for circular sections based on the passive-confinement approach. A new lateral-to-axial strain relationship and failure surface function are developed. Through a comparison with published experimental data, the accuracy of the proposed model is demonstrated.