Dynamic stability testing of isolation systems composed of elastomeric bearings and implications for design

Xing Han, Gordon Patrick Warn, Amarnath Kasalanati

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

3 Citations (Scopus)

Abstract

Elastomeric and lead-rubber seismic isolation bearings have been widely used in the United States and around the world for the past thirty years. During earthquake ground shaking, these bearings will be subjected to vertical compressive loads due to gravity plus seismic forces, accompanied by simultaneous large lateral displacements. The design of isolation systems composed of these bearings, therefore, requires stability of the isolation system and individual bearings at the maximum displacement be demonstrated. The current codified procedure for assessing the stability of individual bearings uses a ratio of areas, referred to as the reduced area method, to determine the critical load capacity of the bearings at a given lateral displacement. This critical load capacity must be greater than a combination of vertical forces imposed on the bearing for stability to be demonstrated. While the reduced area method provides a simple means for estimating the critical load of a bearing at a given lateral displacement, it lacks a rigorous theoretical basis and has been shown to provide inconsistent predictions by comparison to data obtained from quasi-static testing of individual bearings. Dynamic stability testing of two isolation systems composed of four elastomeric bearings was performed at the University at Buffalo using the UB-NEES earthquake simulators to gain an improved understanding of the stability behavior of the individual bearings and global system under representative earthquake ground shaking. This paper presents: (1) a summary of the dynamic stability tests; (2) sample experimental results; and (3) a discussion of the implications for the assessment of stability in design. The new experimental results presented in this paper demonstrate: (1) instability in individual bearings does not necessarily lead to global instability; (2) the state of the global isolation system should be used to assess stability to economize the design; and (3) the reduced area method is not able to accurately predict the global stability of the isolation system.

Original languageEnglish (US)
Title of host publicationStructures Congress 2013
Subtitle of host publicationBridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress
Pages2140-2150
Number of pages11
StatePublished - Oct 17 2013
EventStructures Congress 2013: Bridging Your Passion with Your Profession - Pittsburgh, PA, United States
Duration: May 2 2013May 4 2013

Publication series

NameStructures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress

Other

OtherStructures Congress 2013: Bridging Your Passion with Your Profession
CountryUnited States
CityPittsburgh, PA
Period5/2/135/4/13

Fingerprint

Bearings (structural)
Testing
Earthquakes

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Building and Construction

Cite this

Han, X., Warn, G. P., & Kasalanati, A. (2013). Dynamic stability testing of isolation systems composed of elastomeric bearings and implications for design. In Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress (pp. 2140-2150). (Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress).
Han, Xing ; Warn, Gordon Patrick ; Kasalanati, Amarnath. / Dynamic stability testing of isolation systems composed of elastomeric bearings and implications for design. Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress. 2013. pp. 2140-2150 (Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress).
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abstract = "Elastomeric and lead-rubber seismic isolation bearings have been widely used in the United States and around the world for the past thirty years. During earthquake ground shaking, these bearings will be subjected to vertical compressive loads due to gravity plus seismic forces, accompanied by simultaneous large lateral displacements. The design of isolation systems composed of these bearings, therefore, requires stability of the isolation system and individual bearings at the maximum displacement be demonstrated. The current codified procedure for assessing the stability of individual bearings uses a ratio of areas, referred to as the reduced area method, to determine the critical load capacity of the bearings at a given lateral displacement. This critical load capacity must be greater than a combination of vertical forces imposed on the bearing for stability to be demonstrated. While the reduced area method provides a simple means for estimating the critical load of a bearing at a given lateral displacement, it lacks a rigorous theoretical basis and has been shown to provide inconsistent predictions by comparison to data obtained from quasi-static testing of individual bearings. Dynamic stability testing of two isolation systems composed of four elastomeric bearings was performed at the University at Buffalo using the UB-NEES earthquake simulators to gain an improved understanding of the stability behavior of the individual bearings and global system under representative earthquake ground shaking. This paper presents: (1) a summary of the dynamic stability tests; (2) sample experimental results; and (3) a discussion of the implications for the assessment of stability in design. The new experimental results presented in this paper demonstrate: (1) instability in individual bearings does not necessarily lead to global instability; (2) the state of the global isolation system should be used to assess stability to economize the design; and (3) the reduced area method is not able to accurately predict the global stability of the isolation system.",
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Han, X, Warn, GP & Kasalanati, A 2013, Dynamic stability testing of isolation systems composed of elastomeric bearings and implications for design. in Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress. Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress, pp. 2140-2150, Structures Congress 2013: Bridging Your Passion with Your Profession, Pittsburgh, PA, United States, 5/2/13.

Dynamic stability testing of isolation systems composed of elastomeric bearings and implications for design. / Han, Xing; Warn, Gordon Patrick; Kasalanati, Amarnath.

Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress. 2013. p. 2140-2150 (Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress).

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

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N2 - Elastomeric and lead-rubber seismic isolation bearings have been widely used in the United States and around the world for the past thirty years. During earthquake ground shaking, these bearings will be subjected to vertical compressive loads due to gravity plus seismic forces, accompanied by simultaneous large lateral displacements. The design of isolation systems composed of these bearings, therefore, requires stability of the isolation system and individual bearings at the maximum displacement be demonstrated. The current codified procedure for assessing the stability of individual bearings uses a ratio of areas, referred to as the reduced area method, to determine the critical load capacity of the bearings at a given lateral displacement. This critical load capacity must be greater than a combination of vertical forces imposed on the bearing for stability to be demonstrated. While the reduced area method provides a simple means for estimating the critical load of a bearing at a given lateral displacement, it lacks a rigorous theoretical basis and has been shown to provide inconsistent predictions by comparison to data obtained from quasi-static testing of individual bearings. Dynamic stability testing of two isolation systems composed of four elastomeric bearings was performed at the University at Buffalo using the UB-NEES earthquake simulators to gain an improved understanding of the stability behavior of the individual bearings and global system under representative earthquake ground shaking. This paper presents: (1) a summary of the dynamic stability tests; (2) sample experimental results; and (3) a discussion of the implications for the assessment of stability in design. The new experimental results presented in this paper demonstrate: (1) instability in individual bearings does not necessarily lead to global instability; (2) the state of the global isolation system should be used to assess stability to economize the design; and (3) the reduced area method is not able to accurately predict the global stability of the isolation system.

AB - Elastomeric and lead-rubber seismic isolation bearings have been widely used in the United States and around the world for the past thirty years. During earthquake ground shaking, these bearings will be subjected to vertical compressive loads due to gravity plus seismic forces, accompanied by simultaneous large lateral displacements. The design of isolation systems composed of these bearings, therefore, requires stability of the isolation system and individual bearings at the maximum displacement be demonstrated. The current codified procedure for assessing the stability of individual bearings uses a ratio of areas, referred to as the reduced area method, to determine the critical load capacity of the bearings at a given lateral displacement. This critical load capacity must be greater than a combination of vertical forces imposed on the bearing for stability to be demonstrated. While the reduced area method provides a simple means for estimating the critical load of a bearing at a given lateral displacement, it lacks a rigorous theoretical basis and has been shown to provide inconsistent predictions by comparison to data obtained from quasi-static testing of individual bearings. Dynamic stability testing of two isolation systems composed of four elastomeric bearings was performed at the University at Buffalo using the UB-NEES earthquake simulators to gain an improved understanding of the stability behavior of the individual bearings and global system under representative earthquake ground shaking. This paper presents: (1) a summary of the dynamic stability tests; (2) sample experimental results; and (3) a discussion of the implications for the assessment of stability in design. The new experimental results presented in this paper demonstrate: (1) instability in individual bearings does not necessarily lead to global instability; (2) the state of the global isolation system should be used to assess stability to economize the design; and (3) the reduced area method is not able to accurately predict the global stability of the isolation system.

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Han X, Warn GP, Kasalanati A. Dynamic stability testing of isolation systems composed of elastomeric bearings and implications for design. In Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress. 2013. p. 2140-2150. (Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress).