Influence of structural eccentricity on the bandgap characteristics of frame structures with locally resonant meta-basement

The concept of local resonance has been intensively investigated to create meta-materials and meta-structures for the mitigation of stress wave propagation and structural vibration. The designs of meta-foundation and meta-basement have been proposed to reduce seismic responses of buildings, nuclear power stations and tank structures. However, the existing studies are limited to structures with symmetric plans. In practice, asymmetric plans are very common in many structures, such as high-rise buildings. The misalignment between the center of mass and the center of stiffness, namely eccentricity, could lead to coupled translational-torsional responses, resulting in more complex dynamic behaviors. The conclusions from existing studies of meta-foundation based on symmetric structures on vibration control effectiveness may not be applicable to asymmetric structures with coupled translational-torsional responses. This study aims to fill this research gap by investigating the bandgap properties of asymmetric frame structures with meta-basement. The study begins with a symmetric model to determine the theoretical bandgaps of the meta-basement in the translational and torsional directions separately. The model is subsequently extended to incorporate structural eccentricity for investigation of the bandgap characteristics of asymmetric structures with coupled translational-torsional responses. The vibration control effectiveness of the meta-basement with coupled translational-torsional responses is further assessed through time-history analysis. The results indicate that the meta-basement with locally resonant units exhibits a wider bandgap in the torsional direction than translational direction. The coupling effect changes both the translational and torsional responses and causes the shift of bound frequencies of the bandgap. Consequently, this coupling effect may reduce the overall control effectiveness of the meta-basement as compared to the symmetric structures. • Eccentricity-induced coupled translational-torsional responses of meta-basement is analysed. • Symmetric meta-basement exhibits a wider bandgap in the torsional direction. • The control effectiveness of an asymmetric meta-basement with eccentricity is reduced compared to a symmetric meta-basement.