Exploring the low shape factor concept to achieve threedimensional seismic isolation

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)

Abstract

The current state-of-practice in the U.S., and elsewhere, for designing elastomeric seismic isolation bearings utilizes closely spaced intermediate steel shim plates with thin rubber layers that result in shape factors ranging from 15 to 30. Such high shape factors (HSF) produce a vertical stiffness several thousand times larger than the horizontal stiffness thereby providing isolation only in the horizontal plane (2D). While the large vertical stiffness has been thought to be desirable to minimize rocking in slender structures with an elevated center of mass it also results in a lower period of vibration in the vertical direction that can align with the dominant frequency content of the vertical component of earthquake ground shaking. A low shape factor (LSF) bearing concept to achieve three-dimensional (3D) isolation was explored in the past for the nuclear industry. Though this research demonstrated, through analysis and a prototype design, that the LSF concept could effectively provide isolation in both the horizontal and vertical directions, system level testing and implementation were never realized. This paper presents the results of an analytical, parametric, study aimed to further explore the low shape factor concept to achieve three-dimensional isolation. The results of this study suggest that 3D isolation might be achieved for low and mid-rise structures using the LSF concept if the bearing shape factors are less than four and supplemental vertical damping is included at the plane of base isolation.

Original languageEnglish (US)
Title of host publication20th Analysis and Computation Specialty Conference - Proceedings of the Conference
Pages1-11
Number of pages11
DOIs
StatePublished - Sep 17 2012
Event20th Analysis and Computation Specialty Conference - Chicago, IL, United States
Duration: Mar 29 2012Mar 31 2012

Publication series

Name20th Analysis and Computation Specialty Conference - Proceedings of the Conference

Other

Other20th Analysis and Computation Specialty Conference
CountryUnited States
CityChicago, IL
Period3/29/123/31/12

Fingerprint

Bearings (structural)
Isolation
Stiffness
Vertical
Three-dimensional
Shims
Nuclear industry
Horizontal
Earthquakes
Rubber
Damping
Steel
Testing
Barycentre
Concepts
Earthquake
Vibration
Prototype
Industry
Minimise

All Science Journal Classification (ASJC) codes

  • Computational Theory and Mathematics
  • Applied Mathematics

Cite this

Warn, G. P., & Vu, B. (2012). Exploring the low shape factor concept to achieve threedimensional seismic isolation. In 20th Analysis and Computation Specialty Conference - Proceedings of the Conference (pp. 1-11). (20th Analysis and Computation Specialty Conference - Proceedings of the Conference). https://doi.org/10.1061/9780784412374.001
Warn, Gordon Patrick ; Vu, Bach. / Exploring the low shape factor concept to achieve threedimensional seismic isolation. 20th Analysis and Computation Specialty Conference - Proceedings of the Conference. 2012. pp. 1-11 (20th Analysis and Computation Specialty Conference - Proceedings of the Conference).
@inproceedings{e910635ef764436a8b3eec0e7c2b7ff2,
title = "Exploring the low shape factor concept to achieve threedimensional seismic isolation",
abstract = "The current state-of-practice in the U.S., and elsewhere, for designing elastomeric seismic isolation bearings utilizes closely spaced intermediate steel shim plates with thin rubber layers that result in shape factors ranging from 15 to 30. Such high shape factors (HSF) produce a vertical stiffness several thousand times larger than the horizontal stiffness thereby providing isolation only in the horizontal plane (2D). While the large vertical stiffness has been thought to be desirable to minimize rocking in slender structures with an elevated center of mass it also results in a lower period of vibration in the vertical direction that can align with the dominant frequency content of the vertical component of earthquake ground shaking. A low shape factor (LSF) bearing concept to achieve three-dimensional (3D) isolation was explored in the past for the nuclear industry. Though this research demonstrated, through analysis and a prototype design, that the LSF concept could effectively provide isolation in both the horizontal and vertical directions, system level testing and implementation were never realized. This paper presents the results of an analytical, parametric, study aimed to further explore the low shape factor concept to achieve three-dimensional isolation. The results of this study suggest that 3D isolation might be achieved for low and mid-rise structures using the LSF concept if the bearing shape factors are less than four and supplemental vertical damping is included at the plane of base isolation.",
author = "Warn, {Gordon Patrick} and Bach Vu",
year = "2012",
month = "9",
day = "17",
doi = "10.1061/9780784412374.001",
language = "English (US)",
isbn = "9780784412374",
series = "20th Analysis and Computation Specialty Conference - Proceedings of the Conference",
pages = "1--11",
booktitle = "20th Analysis and Computation Specialty Conference - Proceedings of the Conference",

}

Warn, GP & Vu, B 2012, Exploring the low shape factor concept to achieve threedimensional seismic isolation. in 20th Analysis and Computation Specialty Conference - Proceedings of the Conference. 20th Analysis and Computation Specialty Conference - Proceedings of the Conference, pp. 1-11, 20th Analysis and Computation Specialty Conference, Chicago, IL, United States, 3/29/12. https://doi.org/10.1061/9780784412374.001

Exploring the low shape factor concept to achieve threedimensional seismic isolation. / Warn, Gordon Patrick; Vu, Bach.

20th Analysis and Computation Specialty Conference - Proceedings of the Conference. 2012. p. 1-11 (20th Analysis and Computation Specialty Conference - Proceedings of the Conference).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

TY - GEN

T1 - Exploring the low shape factor concept to achieve threedimensional seismic isolation

AU - Warn, Gordon Patrick

AU - Vu, Bach

PY - 2012/9/17

Y1 - 2012/9/17

N2 - The current state-of-practice in the U.S., and elsewhere, for designing elastomeric seismic isolation bearings utilizes closely spaced intermediate steel shim plates with thin rubber layers that result in shape factors ranging from 15 to 30. Such high shape factors (HSF) produce a vertical stiffness several thousand times larger than the horizontal stiffness thereby providing isolation only in the horizontal plane (2D). While the large vertical stiffness has been thought to be desirable to minimize rocking in slender structures with an elevated center of mass it also results in a lower period of vibration in the vertical direction that can align with the dominant frequency content of the vertical component of earthquake ground shaking. A low shape factor (LSF) bearing concept to achieve three-dimensional (3D) isolation was explored in the past for the nuclear industry. Though this research demonstrated, through analysis and a prototype design, that the LSF concept could effectively provide isolation in both the horizontal and vertical directions, system level testing and implementation were never realized. This paper presents the results of an analytical, parametric, study aimed to further explore the low shape factor concept to achieve three-dimensional isolation. The results of this study suggest that 3D isolation might be achieved for low and mid-rise structures using the LSF concept if the bearing shape factors are less than four and supplemental vertical damping is included at the plane of base isolation.

AB - The current state-of-practice in the U.S., and elsewhere, for designing elastomeric seismic isolation bearings utilizes closely spaced intermediate steel shim plates with thin rubber layers that result in shape factors ranging from 15 to 30. Such high shape factors (HSF) produce a vertical stiffness several thousand times larger than the horizontal stiffness thereby providing isolation only in the horizontal plane (2D). While the large vertical stiffness has been thought to be desirable to minimize rocking in slender structures with an elevated center of mass it also results in a lower period of vibration in the vertical direction that can align with the dominant frequency content of the vertical component of earthquake ground shaking. A low shape factor (LSF) bearing concept to achieve three-dimensional (3D) isolation was explored in the past for the nuclear industry. Though this research demonstrated, through analysis and a prototype design, that the LSF concept could effectively provide isolation in both the horizontal and vertical directions, system level testing and implementation were never realized. This paper presents the results of an analytical, parametric, study aimed to further explore the low shape factor concept to achieve three-dimensional isolation. The results of this study suggest that 3D isolation might be achieved for low and mid-rise structures using the LSF concept if the bearing shape factors are less than four and supplemental vertical damping is included at the plane of base isolation.

UR - http://www.scopus.com/inward/record.url?scp=84866094137&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84866094137&partnerID=8YFLogxK

U2 - 10.1061/9780784412374.001

DO - 10.1061/9780784412374.001

M3 - Conference contribution

SN - 9780784412374

T3 - 20th Analysis and Computation Specialty Conference - Proceedings of the Conference

SP - 1

EP - 11

BT - 20th Analysis and Computation Specialty Conference - Proceedings of the Conference

ER -

Warn GP, Vu B. Exploring the low shape factor concept to achieve threedimensional seismic isolation. In 20th Analysis and Computation Specialty Conference - Proceedings of the Conference. 2012. p. 1-11. (20th Analysis and Computation Specialty Conference - Proceedings of the Conference). https://doi.org/10.1061/9780784412374.001