METAL 3D-PRINTED LATTICE CRESCENT SHAPED BRACE DEVICE TO STRENGTHEN PINNED BEAM-COLUMN CONNECTIONS

In the last century, energy dissipation devices have been developed to mitigate the effects induced by earthquakes on building structures, increasing their seismic performances. They are classified into three main categories: active, semi-active, and passive systems. The first two categories require external power sources, on the contrary, the passive systems operate without power sources and are activated by the structure’s motion. In the last fifty years, different typologies of hysteretic devices, belonging to the category of displacement-activated damping systems, have been developed and tested. Among those, some of the authors introduced the new hysteretic steel device, known as Crescent Shaped Brace (CSB), able to satisfy multiple seismic design performances in terms of stiffness, strength, ductility, and ultimate capacity, thanks to its geometrical shape. The present work explores the use of CSB hysteretic devices as dissipative beam-column connections to improve the seismic performances of pinned steel frames. The devices are designed to provide the required stiffness and strength, thus leading to semi-rigid joints. A simplified moment-rotation analytical model is derived to describe the kinematic and mechanical response of joint CSBs. The model, which is suitable for preliminary seismic design, is validated through Finite Element analysis. Then, the joint CSB is designed for Wire-and-Arc Additive Manufacturing (WAAM) considering process possibilities in terms of geometrical complexity (topology optimization) and manufacturing constraints.