REPARABILITY ASSESSMENT OF A LARGE-SCALE STEEL STRUCTURE EQUIPPED WITH FRICTION-BASED DISSIPATIVE BRACES AND SELF-CENTRING COLUMN BASES

Over the last few decades, increasing research efforts have been devoted to the development of innovative seismic resilient design strategies to reduce both direct and indirect seismic losses. Among others, the use of dissipative braces in steel Concentrically Braced Frames (CBFs) has proven to be an effective solution for achieving high stiffness, strength, and energy dissipation capacity. These braces typically consist of an elastic brace paired with a dissipative device, which can be either displacement- or velocity-dependent. Friction Devices (FDs) represent a common type of displacement-dependent device, characterised by an almost perfectly plastic behaviour and minimal structural damage. However, while their energy dissipation capabilities are valuable, their low hardening response can impair the structure’s ability to self-centre after a seismic event, potentially leaving residual drifts that complicate repair and affect seismic resilience. To address these challenges, recent research has demonstrated how the use of such devices, combined with Self-Centring Column Bases (SC-CBs), can be beneficial for reducing residual drift and enhancing reparability. Despite their potential benefits, the application of these systems in steel CBFs has received limited attention. To address this gap, an experimental campaign was conducted on a large-scale, two-story steel structure integrating dissipative braces with FDs and SC-CBs. A series of pseudo-dynamic tests were performed at varying intensity levels, and after each test, repairs were carried out by simply loosening the bolts of the FDs in the braces. This paper presents the design of the test specimen, the experimental programme, and preliminary findings, which highlight the effectiveness of SC-CB connections in minimizing residual drifts, protecting first-story columns from damage, and improving the system’s reparability.