Global sensitivity analysis of metabarriers for seismic surface wave attenuation using surrogate modeling

We investigate the impact of the uncertainty associated with three key mechanical parameters (i.e., soil density, soil shear modulus, and mass of mechanical resonators) on the seismic isolation performance of a metabarrier. The latter constitutes a novel class of elastic metamaterials engineered to attenuate ground-induced vibrations and shield vulnerable structures or infrastructures against seismic surface waves [1]. It relies on a cluster of locally resonant pillars or mechanical resonators installed on the soil surface. Seismic metabarriers are passive isolation devices tailored to operate at specific frequency ranges. Once the motion of incoming surface waves activates the resonators, they can deflect and convert the traveling surface waves into bulk shear waves [2]. Achieving the proper design and implementation of seismic metabarriers requires a comprehensive knowledge of the role played by the model parameters governing soil-barrier dynamic interaction. In this context, global sensitivity analysis (GSA) techniques can be employed to quantify the influence that parameters of seismic metabarriers and their associated uncertainty have on their response [3]. We rely on a two-dimensional numerical model which is developed according to the wave finite element approach [4], and evaluate the dispersion relation and transmission coefficient of a metabarrier interacting with seismic surface waves in the low-frequency regime. Given the heavy computational burden of the numerical model, we rest on a surrogate modeling technique. Our results suggest that the soil shear modulus is the parameter with the most significant influence on the transmission coefficient of the metabarrier across the entire frequency range of interest. We then find that the resonator mass plays a substantial role in the frequency limit close to the operating frequency of the metabarrier [5]. This study provides new insights into the rational design of seismic metabarriers, which can impact several civil engineering areas, including geotechnical engineering, road and railway traffic, and earthquake engineering.