Hybrid confinement of high strength concrete using shape memory alloys and fiber-reinforced polymers

This exploratory study investigates an innovative hybrid confinement technique for high-strength concrete (HSC) which combines traditional passive confinement applied using fiber-reinforced polymer (FRP) sheets with active confinement applied using thermally pre-stressed shape memory alloy (SMA) spirals. Normal strength concrete (NSC) and HSC cylinder specimens, confined either with traditional FRP confinement or hybrid confinement, are tested under uniaxial cyclic compression. Test results indicate that the application of hybrid confinement on HSC with a small active component results in a significantly higher ductility in comparison to passively confined HSC. The experimental test results are then used to carry out pushover analysis of high strength concrete-filled fiber tube (CFFT) bridge columns wrapped with SMA spirals. The pushover analyses show that the application of active confinement improves the ultimate drift ratio of high strength CFFT columns.