Pilot Study of Behavior of Concrete Beams Reinforced with Shape Memory Alloys

Abstract

This paper discusses the superelastic behavior of shape memory alloy, Nitinol (NiTi) , when used as reinforcement in concrete beams. The ability of NiTi to recover and reduce permanent deformations of concrete beams was investigated. Small-scale concrete beams, with NiTi reinforcement were tested under half-cycle loads. The reinforcement ratio varied from 0.1 to about 0.9%. The experimental results showed that the average residual displacement in the NiTi reinforced beams was less than one-fifth of that of the steel reinforced test beams. The stiffness of NiTi reinforced test beams however was lower than those of the steel reinforced test beams. An analytical study of load–deflection relationship for a series of hybrid beams was undertaken. It was found that a hybrid system that incorporated NiTi combined with high strength steel or carbon fiber reinforced plastic bars was a better choice for design because of their relatively high stiffness.