Large-Scale Validation of Innovative SMA Recentering Devices for Multi-Span Bridges

Reginald DesRoches and Jamie E. Padgett

This study will use the NEESR-0420347 setup to validate the use of Shape Memory Alloy (SMA) recentering devices in multi-span bridges. Shape Memory Alloys are a class of unique alloys that have the ability to undergo large displacements, and revert back to their original undeformed configuration (Figure 1.) via a martensitic transformation. Previous work by the PI has focused on the optimization of the properties of the alloys such that they can be used in seismic applications. The results of previous component testing and analytical work will be validated by designing, developing, and testing innovative SMA devices on the four-span bridge built at the UNR Laboratory.

Two sets of devices will be developed and tested (at the locations shown in Figure 2) including (1) bundled SMA wire, and (2) Optimized SMA bars. Large-scale validation, as provided by this study, is the first step towards the acceptance of a new class of materials for seismic retrofit of bridges. The experimental tests will be coupled with analytical studies using OPENSEES to determine the optimal properties of the devices. Results from the analytical models will be used in development of bridge fragility curves to illustrate the viability of these SMA recentering devices in typical bridges.