Seismic performance assessment of pinching-free tension-only CBFs equipped with aluminium metal foam dampers

Metal foams are emerging as attractive materials for civil engineering applications, able to balance excellent stiffness-to-weight ratios with high damping and energy dissipation capacity compared to conventional building materials. Although applications for metal foams are mainly emerging in the mechanical, aerospace, and automotive industries, their use in building structures is still quite limited. Thanks to their excellent energy dissipation properties, metal foams can be effectively employed in innovative damping devices, addressing the demand for high-performance structural solutions. In this context, this work proposes a possible solution to realise dissipative replaceable Aluminium Foam Dampers (AFD) to be applied in Tension-Only Concentrically Braced Frames (TO-CBFs). The bracing system comprises a steel rod linked to an aluminium foam damper, providing the structure with high dissipation capacity when activated under compression. A wedge system is implemented to ensure the system operates under tension-only conditions while preventing buckling. 1- and 2-storey X-braced steel frames are designed according to Eurocode 8 provisions by considering conventional and innovative configurations implementing the proposed AFDs. 2-D FE models are developed in OpenSees to assess the seismic performance of case-study structures through the Incremental Dynamic Analyses (IDA) methodology. Fragility curves are successively developed to provide a probabilistic evaluation of the results. The results of the conventional and innovative systems are compared, showing the AFD's influence on the frames’ seismic performance.