Design for Additive Manufacturing of Crescent Shaped Brace Device to Strengthen Pinned Beam-Column Connections

In the previous century, energy dissipation mechanisms were created to reduce the impact of earthquakes on building structures, thereby enhancing their seismic performances. These mechanisms fall into three primary categories: active, semi-active, and passive systems. The first two categories rely on external power sources, whereas passive systems operate without external power and are activated by the motion of the structure. Over the past five decades, various types of hysteretic devices, belonging to the displacement-activated damping systems category, have been developed and tested. Among them, some of the authors introduced a novel hysteretic steel device known as the Crescent Shaped Brace (CSB), which can meet multiple seismic design requirements in terms of stiffness, strength, ductility, and ultimate capacity, thanks to its unique geometric configuration. This study investigates the utilization of CSB hysteretic devices as dissipative connections for beam-column joints to enhance the seismic performances of pinned steel frames. These devices are engineered to provide the necessary stiffness and strength, resulting in semi-rigid connections. A simplified analytical model for moment-rotation behavior of CSB joints is formulated to describe their kinematic and mechanical response. This model, suitable for initial seismic design considerations, is validated through Finite Element analysis. Subsequently, the CSB joint is designed for Additive Manufacturing, specifically employing Wire Arc Additive Manufacturing (WAAM) technology. This design takes into consideration manufacturing constraints associated with dot-by-dot WAAM printing, as well as structural considerations. It results in the design and the initial structural analysis of the first CSB prototype.