Axial Stress–Strain Model for Concrete Actively Confined with Fe-SMA Strips

Abstract

This study explored a new scheme for active confinement of concrete using cost-effective Fe-shape memory alloy (Fe-SMA) strips as an alternative to the expensive NiTi-based SMAs. The axial stress–strain behavior of concrete partially wrapped with Fe-SMA strips was investigated experimentally. The failure modes were observed to shift from brittle to ductile with the increase in confining pressure, which was achieved by reducing the spacing of Fe-SMA hoop strips. An empirical stress–strain model is proposed for accurate prediction of behavior of Fe-SMA–confined plain concrete. The proposed model for Fe-SMA–confined concrete and Mander et al.’s model for steel rebar confined concrete were combined to propose a model for predicting the behavior of Fe-SMA–confined RC specimens. Three-dimensional finite-element analyses of concrete specimens with various concrete strength, internal reinforcement, and external Fe-SMA confinements were carried out, and an empirical model is proposed for further improved prediction of uniaxial compressive behavior of Fe-SMA–confined RC specimens.