Presentation Title

Performance Assesment of Metamaterials for Seismic Isolation

Faculty Mentor

Giuseppe Lomiento

Start Date

18-11-2017 11:00 AM

End Date

18-11-2017 11:15 AM

Location

9-243

Session

Engineering/CS 1

Type of Presentation

Oral Talk

Subject Area

engineering_computer_science

Abstract

Seismic isolation is recognized as an effective technology to achieve high levels of protection against seismic forces. Despite their effectiveness, currently used seismic isolators have practical, technical and economical limitations, which result in their application to critical structures only. Metamaterial pads have been recently proposed as an alternative solution to overcome these limitations and expand the application of this technology to residential homes, retail stores, and equipment.

Metamaterials are artificial materials where the properties are dictated by a specifically constructed pattern of voids within the material itself. In this research, isolation pads containing a specifically designed metamaterial are investigated for the seismic isolation of server racks.

The methods used to conduct this research include, physical laboratory testing and numerical analysis. The isolation pads were first subjected to dynamic testing, with a block of concrete representing the mass of the server rack. Acceleration data for both the ground motion and the concrete block in two horizontal directions was gathered from the test. Examination of the test data showed all block accelerations were within acceptable values, and so the isolation pads were considered successful for these levels of seismic activity.

Once the data from the physical test was analyzed, a model of the lab test was created in the software SAP2000 and subjected to the same seismic forces. The model was calibrated to match the data from the physical test. The experimentally calibrated model was then used to assess the performance of typological server racks for different levels of ground shaking.

Summary of research results to be presented

The experimental data was gathered for a number of ground motions obtained by scaling a bi-directional waveform with factors ranging from 10% and 125% the original intensity. Data was then graphed and analyzed to find the relationship between the ground motion acceleration and the acceleration of the isolated test block. The results from a comparison of peak values showed that the isolators kept the acceleration of the block below two and a half times the ground motion acceleration in both directions. In certain intervals of low seismic force the block’s acceleration was even below that of ground motion.

The numerical model is expected to produce similar results. The isolation pads should keep the acceleration of the block well below that of a non-isolated block. However, with increasing seismic force applied, the isolators will eventually reach their maximum displacement, and will not provide any additional protection from acceleration, but will still restrain the lateral motion of the protected object.

This document is currently not available here.

Share

COinS
 
Nov 18th, 11:00 AM Nov 18th, 11:15 AM

Performance Assesment of Metamaterials for Seismic Isolation

9-243

Seismic isolation is recognized as an effective technology to achieve high levels of protection against seismic forces. Despite their effectiveness, currently used seismic isolators have practical, technical and economical limitations, which result in their application to critical structures only. Metamaterial pads have been recently proposed as an alternative solution to overcome these limitations and expand the application of this technology to residential homes, retail stores, and equipment.

Metamaterials are artificial materials where the properties are dictated by a specifically constructed pattern of voids within the material itself. In this research, isolation pads containing a specifically designed metamaterial are investigated for the seismic isolation of server racks.

The methods used to conduct this research include, physical laboratory testing and numerical analysis. The isolation pads were first subjected to dynamic testing, with a block of concrete representing the mass of the server rack. Acceleration data for both the ground motion and the concrete block in two horizontal directions was gathered from the test. Examination of the test data showed all block accelerations were within acceptable values, and so the isolation pads were considered successful for these levels of seismic activity.

Once the data from the physical test was analyzed, a model of the lab test was created in the software SAP2000 and subjected to the same seismic forces. The model was calibrated to match the data from the physical test. The experimentally calibrated model was then used to assess the performance of typological server racks for different levels of ground shaking.