Hierarchical seismic metamaterial design toward enhancing multidirectional seismic attenuation

The advent of seismic metamaterials (SMs) presents a new technology for protecting infrastructures from earthquakes. Their unique strength in guiding seismic wave propagation results in superior energy absorption compared to conventional methods. Despite the recent surge in seismic metamaterial research, achieving high-performance multidirectional wave attenuation upon actual SM deployment remains a challenge. To tackle this issue, we develop a high-fidelity modeling approach in this research that allows one to characterize the multidirectional seismic attenuation performance of SMs in real-world scenarios. This approach is further integrated with tailored features to achieve rapid performance assessment. Using this approach as a backbone, a hierarchical design, aiming at identifying the optimal unit cells and their arrangement pattern, is conducted to enhance the multidirectional seismic attenuation performance. This study offers a novel perspective on the design of SMs by integrating realistic considerations, which demonstrates practical applicability and significance. The effectiveness of the proposed framework is thoroughly validated by practicing an SM design implementation. Specifically, an embedded unit cell made of steel and rubber is developed, followed by the pattern design to synthesize the SM. SMs incorporating these unit cells in 2D graded patterns show a significant improvement in multidirectional seismic attenuation performance compared to those with non-graded and 1D graded patterns.