Seismic Performance Assessment of a Passive Control Technology for Bridges Using Shape Memory Alloys

The performance of restrainer cables made of Nitinol shape memory alloys (SMA) is evaluated using a large-scale test setup. The performance was evaluated on both a ¼-scale in-span hinge model, and a ¼-scale continuous bridge model, using a range of ground motion levels. The results indicate that the SMA restrainer cable was extremely effective in limiting the hinge displacement, while simultaneously limiting the acceleration due to impact. Using the results from the experimental tests, a probabilistic seismic risk assessment is performed. Vulnerability curves are developed for a bridge model with traditional steel restrainer cables and SMA restrainer cables. The results show that for the higher damage states, the SMA restrainer cables become exceedingly more effective in limiting damage or collapse when compared with traditional steel restrainer cables. Finally, a benefit-cost study is performed, and a comparison between SMA cables and steel cables is presented. The results show, despite the increase in cost for SMA restrainer cables, the enhanced performance results in a higher benefit-cost ratio.