Applications of shape memory alloys in civil engineering structures—Overview, limits and new ideas

Abstract

Shape memory alloys (SMAs) are metallic materials with great potential to enhance civil engineering structures. They are often referred to as smart materials. A basic description of their highly non-linear material behaviour in terms of shape memory effect, superelasticity, martensite damping and variable stiffness is given in this article. It is followed by a brief introduction to Ni−Ti and Fe−Mn−Si SMAs. Pre-existing and new applications in the fields of damping, active vibration control and prestressing or posttensioning of structures with fibres and tendons are being reviewed with regard to civil engineering. Furthermore, the relatively high costs and the problem of retaining posttensioning forces when using some types of SMAs are named. In this regard is Fe−Mn−Si−Cr discussed as potential low cost SMA. A simple model for calculating the activation times of resistive heated SMA actuators or springs is presented. The results and measured data lead to further constrictions. Finally, new ideas for using SMAs in civil engineering structures are proposed in this article such as an improved concept for the active confinement of concrete members. This article is to introduce civil engineers to the world of shape memory alloys and invite them to contribute to their wider use in civil engineering structures.