Resilient clevis-based connections equipped with hybrid Ni-Ti shape memory alloys and steel tendons : experimental and FE investigations

Shape memory alloys (SMAs) are a group of novel materials capable of withstanding large deformations and returning to their initial state using specific mechanisms. This unique capability has led to their increasing use in various engineering fields, especially in engineered structures, to maximize the recentering capability and minimize the residual deformations under dynamic loadings. Despite having the ability to withstand large deformations without being ruptured or damaged, these materials have moderate energy absorption and dissipation capacity. Therefore, this study examines the behavior of a novel type of clevis-based beam-to-column connection, which is categorized as a semi-rigid joint and is made of a combination of SMA and steel tendons using experimental and numerical investigations. The reason for combining steel tendons with SMA tendons is to investigate the influence of increasing energy absorption capability and reducing permanent deformation of the connection. The connection is made by incorporating steel tendons and SMA tendons, each in two different sizes, with varying arrangements under four different cyclic loading protocols, representing far- and near-field strong ground motions. From a total of 24 experiments and subsequent numerical investigations, it was observed that the proposed connection has an excellent recentering capability with a maximum of 0.004 (radian) recoverable deformation and large energy dissipation capacity with equivalent viscous damping of up to 35% after being subjected to cycles up to 6% drift. In contrast, tendons have improved its overall resilience and behavioral characteristics.