<title>Innovative beam column connections using shape memory alloys</title>

Abstract

The application of Nitinol shape memory alloys (SMA) in steel connections is evaluated using connections incorporating SMA tendons. Shape memory alloys are a class of alloys that exhibit thermo-mechanical characteristics that are ideally suited for seismic applications. They have the ability to dissipate significant energy with little permanent deformation, and possess highly reliable energy dissipation based on a repeatable solid state phase transformation. To assess the validity of using SMA in real structures, two full-scale connections are tested. The tests are conducted on exterior joint specimens and tested according to the SAC testing protocol. The beams are W24 x 94 and the columns W14 x 159, all of A572 Grade 50 steel. Companion regular steel connections are tested for comparison. The connections are of a T-stub type, with four 11/2 inch diameter SMA rods providing the tensile resistance to the column. The specimens are re-tested several times to determine the ability of the SMA rods to regain their original configuration. The tests will lead to the development of an innovative beam-column connection that can be used for both retrofit and new construction that exhibits performance which is superior to existing designs.