Uniaxial Compression Behavior of Actively Confined Concrete Using Shape Memory Alloys

This experimental study focuses on investigating the uniaxial compressive behavior of concrete cylinders confined using a novel active confinement technique. Shape memory alloy (SMA) spirals are utilized to apply external confining pressure on the concrete cylinders. Thermomechanical tests are conducted to determine the recovery stress of the used spirals. In addition the uniaxial compressive behavior of the actively confined concrete using SMA spirals and hybrid wraps made with Glass Fiber Reinforced Polymers (GFRP) and SMA wires is studied and compared with unconfined and passively confined concrete. The results of the study show that SMA spirals are effective in applying large and reliable active confining pressure on concrete. The confining pressure produced by SMAs results in a significant increase in concrete strength and ductility compared to unconfined and passively confined cylinders.