The ultimate condition of FRP confined concrete columns: New experimental observations and insights

Abstract

A large body of research is available on FRP confinement of concrete. Many hundreds of tests have been performed and dozens of empirical models are available. However, some of the key mechanics of FRP wrapped concrete are still not understood. Research is needed to understand, quantify, and rationally account for the hoop strain variation in FRP wraps at failure; since failure is fundamentally defined by hoop rupture of the FRP in tension. In this paper, a digital image analysis technique is used to quantify the variation of axial and hoop strain over the surface of FRP wrapped concrete cylinders. Tests on FRP wrapped cylinders of varying aspect ratio are presented to study factors influencing strain variability. The first ever quantified statistical description of hoop strain variability is provided, and the consequences of this variability are discussed. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2011.