Experimental Evaluation of a New Bridge Retrofit Device: Shape Memory Alloy Restrainers

Past earthquakes have illustrated the vulnerability of bridges to collapse as a result of large relative displacements at the hinges. In this study, Nitinol Shape Memory Alloy restrainer cables are evaluated for their potential to limit the relative hinge displacement in bridges. Shape Memory Alloys are unique metallic alloys that have the ability to sustain large elastic deformations. Experimental studies of a two span bridge with in-span hinges with SMA restrainers show that they are much more effective in limiting the hinge displacement.and and deck accelerations compared with traditional steel restrainer cables. Subsequent tests of a 4 span concrete bridge shows that the SMA restrainers are particularly effective in limiting hinge displacements when the cables are pre-strained.