On the Design of Seismic Metamaterials Accounting for Site Effects

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

The use of elastic metamaterials, i.e., artificial engineered media equipped with distributed local resonant units, has shown potential for the realization of novel earthquake isolation systems. The design of such resonant structures requires an adequate description of the local seismic response, also known as site effects, which is determined by the complex dynamics of the near-surface layers. Site effects are in fact responsible for significant changes in the amplitude, frequency and duration of seismic waves, which cannot be neglected for a meaningful assessment of seismic metamaterials performances.

In this talk, we analyze the isolation capabilities of seismic barriers realized by embedding meter size resonant units below the ground surface and accounting for complex soil profiles and realistic earthquake ground motions. We apply random vibration theory and equivalent linear analysis (EQL), to perform 1D site responses and evaluate the amplification of the ground motion at the soil surface for a representative seismic motion at the bedrock, soil profile and seismic barrier design. To this aim, we consider a set of synthetic soil profiles generated using a sediment velocity model (SVM) conditioned on VS₃₀ and model the presence of the resonant barrier using an equivalent resonant layer, with frequency dependent dynamic properties. The low computational cost of the EQL method allows us to investigate a large parameter space of barrier configurations and soil profiles. We optimize the barrier for specific soil profiles and given designs constraint (overall dimensions, mass, material damping) and provide realistic estimates of reduced amplification factors at specific sites.

Presenting Author: Antonio Palermo

Authors