Seismic steel frames enhanced with locally resonant metastructures for reduced embodied carbon

This paper introduces controlled steel buildings endowed with novel locally resonant metastructures inspired by metamaterial concepts. A major limitation of finite locally resonant metastructures in low-frequency vibration control is the requirement for large additional masses. Conversely, properly designed periodic structures inside a main structure can function as locally resonant metastructures with limited extra mass and proper damping. By incorporating locally resonant metamaterials, this study advances the potential of seismic steel frames, to enhance seismic performance while reducing material usage, thus addressing both structural efficiency and sustainability. Therefore, our research covers both the elastic and the inelastic range, where frames are optimally designed to meet both immediate occupancy and life safety performance limit states. In addition, two case studies, one involving a 25-story moment resisting steel frame and the other focusing on a 20-story eccentrically braced steel frame structure, are analyzed to demonstrate the efficacy of the proposed approach. A multi-objective optimization methodology is employed to illustrate the trade-off between metastructure inherent damping ratio and material usage, i.e. embodied carbon emissions, highlighting the environmental benefits alongside structural performance improvements. The results demonstrated that optimal mass reduction for the proposed metastructures in both lateral-resisting systems was feasible, with reduction rates of at least 11.3% and 13.7% without additional damping in the metastructures compared to the original configurations. Finally, the reduction in embodied carbon was analyzed based on the material usage in the framed structures.