Exploratory Study of Seismic Response of Concrete Columns with Shape Memory Alloys Reinforcement

Superelastic shape memory alloys (SMAs) are unique materials that have the ability to undergo large deformation, but can recover deformations fully upon load removal. The primary objective of this study was to investigate if this characteristic of SMAs can be harnessed to reduce residual displacement of concrete columns that are reinforced with SMA bars in the plastic hinge area. Another target was to evaluate seismic performance and damage in a SMA-reinforced column that is repaired using engineered cementitious composites (ECC). Two quarter-scale spiral reinforced concrete (RC) columns with SMA longitudinal reinforcement in the plastic hinge area were tested on a shaketable. The data showed that SMA- reinforced columns were able to recover nearly all of post-yield deformation and that the use of ECC reduced the concrete damage substantially, thus requiring minimal repair even after a strong earthquake. A new hysteresis model for SMA-reinforced members led to close correlation with the measured displacement histories for both test specimens.