Seismic retrofit strategy for existing steel buildings with CBFs

Recent advancements in materials engineering have introduced new possibilities in the field of Civil Engineering. A noteworthy example is the development of metal foam, an innovative material with a favourable weight-to-stiffness ratio and excellent damping and energy dissipation properties. The increasing interest in the characteristics of metal foam has motivated researchers to explore innovative solutions for dissipative dampers. An example of such application regards the use of dissipative aluminium foam dampers in steel Concentrically-Braced-Frames (CBFs). In this bracing system, a steel rod or tube is connected to an aluminium foam damper which provides the structure with energy dissipation capacity when subjected to compression forces. A wedge device is employed to absorb the permanent deformations of the aluminium foam, preventing any pinching behaviour in the overall response. This research offers an opportunity to assess the effectiveness of such a solution by studying an existing two-storey steel structure. The structural design includes pinned frames that support gravity loads, while CBFs are responsible for resisting horizontal forces generated by wind and seismic actions. However, as this structure was built in the early '80s, predating the availability of seismic design rules, it requires retrofitting interventions to improve its seismic performance. This manuscript presents the application of dissipative aluminium foam dampers for the seismic retrofitting of the analysed building.