DOI: 10.17603/ds2-c7wn-kj59
title: Seismic Isolation of Embedded Foundations Using Periodic Meta-material Barriers to Create Resilient Structures
title: in Collaborative Research: Seismic Isolation of Embedded Foundations Using Periodic Meta-material Barriers to Create Resilient Structures

description: This field experiment evaluated the performance of periodic metamaterial-based barrier, called periodic barrier, under different vibration tests. The tests are divided into a) passive isolation test and b) active isolation test. T-Rex was used in passive isolation test and Thumper in active isolation test. Metamaterial periodic barrier was installed on field with various combinations of length and numbers to study the parametric behavior and the effect on vibration isolation performance of the barrier. The data was gathered using series of 3D geophone sensors and accelerometers installed on the experiment field as described in the sensor layout of the field experiment. Various excitation inputs such as Fix-frequency harmonic, Frequency sweep, and Earthquake excitations are used in this experiment. The results showed that the performance of the periodic barrier is dependent on the excitation frequency and excitation direction. The data is valuable for understanding the dynamic behavior of the periodic barrier, and researchers can use the data to validate their numerical models.
description: Evidence in recent severe earthquakes shows that conventional seismic isolation systems are effective in reducing the damage from horizontal components of earthquake shaking. However, conventional isolation systems are not well suited for protection against the vertical components of earthquake shaking, nor can they be readily used for embedded or underground structures. In this publication, we present field experiment data and numerical simulation results generated from an investigation of metamaterial-based seismic isolation systems of embedded or underground structures. The metamaterial foundations, which also act as the foundation of the superstructure, can isolate seismic waves coming from the soil beneath the embedded foundations. Metamaterial barriers, on the other hand, will isolate the embedded structures from the incoming lateral seismic waves. The combination of metamaterial barriers and metamaterial foundation forms an isolation envelope for the embedded foundations. 

To understand the effectiveness of the combined metamaterial barriers and the metamaterial foundation systems, our project modeled the metamaterial barriers through a series of numerical simulations whose results were validated with field experiment data. The field experiment data – gathered for various excitation inputs generated using the T-Rex three-axis shaker, and Thumper three-axis shaker (both from NHERI@UTexas) by 3D geophone sensors and accelerometers - examine how seismic waves propagate in soil with and without metamaterial barriers. 

The finite element simulations include parametric study and seismic vibration isolation performance study of the metamaterial barrier under various excitation inputs. The finite element simulation and field experiment results show that the filtering capability of the metamaterial barrier and foundation are complementary to each other, and the combined usage of the metamaterial barrier and the metamaterial foundation is beneficial to mitigating vibration of the protected superstructure. 

The project field experiment resulted in the generation of a rich data set that can be used to study and understand how the metamaterial periodic barrier isolates vibrations and parametric the behavior of the system and can design the seismic vibration isolation system for underground or embedded structures and foundations. The design of non-seismic event isolation systems for heavy machinery applications as well as isolation systems for extremely sensitive manufacturing and medical equipment can be improved by the theoretical and field experiment results of this project. The data resultant from the field experiment tests is hereby published as “Seismic Isolation of Embedded Foundations Using Periodic Meta-material Barriers to Create Resilient Structures”.  The numerical simulations and validation results are included the Final Report also published in this project. We include links to related publications in Related Works.