A study of RC columns with shape memory alloy and engineered cementitious composites

The interest in Shape Memory Alloys (SMAs) in structural engineering applications has been growing over the past several years. SMAs are unique alloys that have the ability to undergo large deformation, but can recover deformations fully after the loads. However, there is no research reported on the ability of SMA to be used as reinforcement for plastic hinge area in reinforced concrete (RC) columns. Engineering Cementitious Composties (ECC) is another innovative material that has very high tensile and deformation capacity compared to normal concrete, which can make it deformable with much delayed cracking and spalling. The primary objective of this study was to investigate the seismic performance of RC columns with SMA longitudinal reinforcement in plastic hinge area. Another target was to evaluate seismic performance and damage in a repaired SMA-reinforced column using ECC.; Two quarter-scale spiral RC columns with SMA longitudinal reinforcement in the plastic hinge area were designed and constructed for shake table testing at the Large Scale Structure Laboratory of University of Nevada, Reno. Similar conventionally reinforced columns had been studied previously at UNR and provided a basis for evaluating the effect of using SMA bars and ECC. A new hysteresis model for SMA-reinforced columns was developed and was found to reproduce the measured dynamic data well. The shake table data showed that SMA RC 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 very large earthquake.