Achieving targeted levels of reliability for low-rise seismically isolated structures

Shao, Benshun; Mahin, Stephen A.; Zayas, Victor A.

doi:10.1016/j.soildyn.2019.105744

Cited by 15 publications

(12 citation statements)

References 28 publications

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“…The study focuses on the applications on the low-rise structures with a relative short period where most of the deformation concentrates within the isolation plane. Two superstructure models including a base-isolated ordinary concentrically braced frame (BI-OCBF) and a base-isolated intermediate steel moment resisting frame (BI-IMRF) (Shao et al, 2019) are used, which represent a relatively stiff and a relatively flexible superstructure. This bounds a wide range of cases in practical design for low-rise seismically isolated structures.…”

Section: Determination Of System Uncertainty βTotmentioning

confidence: 99%

“…Note if spectra shape factor is considered, the obtained CMR Target should be further adjusted before being used to scale the ground motion. However, for seismically isolated structure, cautions should be made when determining spectra shape adjustment factor (Kitayama and Constantinou, 2018; Shao et al, 2019).…”

Section: Determination Of βRtrmentioning

confidence: 99%

“…However, a fundamental and critical issue in practical design for the seismically isolated structure is to ensure that it meets the targeted reliability with an acceptable probability of “collapse.” This could be either triggered by the global collapse of the superstructure or the failure of the isolation system, as the isolation system frequently serves as the gravity supporting system of the superstructure. The integrity of superstructure is generally achieved by providing enough lateral strength and deformation capacity, the failure of the isolation system is not sufficiently addressed in current design regulations (Shao et al, 2019). A critical problem is how large the capacity of the isolation system must be to avoid premature failure and achieve the targeted reliability for the entire structural system (Iiba et al, 2008; Shao and Mahin, 2016, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…It is commonly used as the isolator displacement capacities in practical design with minor torsional reserve capacity. Previous studies (Kitayama and Constantinou, 2018, 2019; Shao, 2018; Shao et al, 2019) indicate that design considering the average MCE R demand results into an unacceptable probability of failure for the isolation system due to its inadequate deformation capacities, especially for high-risk category. This governs the probability of collapse for the global structural system.…”

Section: Introductionmentioning

confidence: 99%

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A probabilistic design method to achieve targeted levels of reliability for seismically isolated structures

Shao

Mahin

2020

Earthquake Spectra

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Previous studies conclude that additional capacities of isolation system are needed beyond minimum demand required in minimum design loads for buildings and other structures (ASCE 7) to achieve the targeted level of reliability for seismically isolated structures. To implement this concept for practical design, a probabilistic design method with minor computational cost is proposed to obtain the isolation system capacities based on the targeted failure fragility. As an essential statistical parameter for determining the fragility curve shape, total system uncertainty value ( βTOT) is needed. Among different sources of βTOT, the record to record uncertainty ( βRTR) contributes most to the isolator deformation demand and is challenging to obtain for a specific design case. A simplified procedure with minor computational cost has been proposed for estimating βRTR when failure is governed by the isolators. Main assumptions and simplifications in the proposed design method have been investigated and justified. Finally, a step-by-step procedure for implementing the proposed probabilistic design method has been introduced. A design example was given, and the three-dimensional incremental dynamic analysis was performed to validate the design method.

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Section: Determination Of System Uncertainty βTotmentioning

confidence: 99%

Section: Determination Of βRtrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A probabilistic design method to achieve targeted levels of reliability for seismically isolated structures

Shao

Mahin

2020

Earthquake Spectra

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“…Deprem yalıtımlı yapı tepkilerini belirlemek için literatürde yer alan çalışmalara bakıldığında öne çıkan bir diğer önemli nokta da dinamik analizlerin tek doğrultulu [10][11][12] ya da çift doğrultulu [13][14][15] deprem etkileri altında yürütülmesidir. Özdemir ve Akyüz [16] çift ve tek doğrultulu deprem etkileri altında yürüttükleri analizler sonucunda MİD'in ne ölçüde etkilendiğini göstermek üzere, çift doğrultulu analizler ile edilen yalıtım birimi deplasmanlarını tek doğrultulu analizlerden elde edilenler ile kıyaslamışlardır.…”

Section: Introductionunclassified

Comparison of Design Spectra in Turkish Earthquake Codes (TEC and TBEC) in Terms of Seismic Isolator Design

2021

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Binalar Hakkında Yönetmelik koşulları dikkate alınarak tasarlanmış deprem yalıtımlı bir yapı modeli için, spektrum tanımındaki değişime bağlı olarak maksimum yalıtım birimi deplasmanının nasıl etkilendiği incelenmiştir. Yapıdaki deprem yalıtım sitemi kurşun çekirdekli kauçuk yalıtım birimlerinden oluşurken, seçilen ve ölçeklenen deprem kayıtlarına ait yatay bileşenlerin eş zamanlı etkisine maruz bırakılmıştır. Analizler, çevrimsel yükleme altında yalıtım birimindeki dayanım kaybını dikkate alan ve almayan durumlar için tekrarlanmıştır. Yalıtım birimi dayanımını temsilen Q/W oranı ve yapının inşa edileceği alan seçilen parametrelerdir. Sonuç olarak, her iki deprem yönetmeliğinin tanımladığı spektrum eğrilerine göre tasarlanan yalıtım birimlerinin maksimum deplasmanlarında yapı koordinatına bağlı olarak farklılaşma %50 mertebelerine varabilmektedir. Yalıtım birimindeki dayanım kaybının dikkate alındığı durumlar için bu farklılaşmanın daha da fazla olduğu kaydedilmiştir.

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Effect of superstructure modeling assumptions on the seismic performance of seismically isolated buildings

Kitayama

Constantinou

2021

Earthq Engng Struct Dyn

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Recent studies on the seismic performance of seismically isolated buildings with braced frames designed using the minimum criteria of the ASCE 7-16 standard resulted in observations that seismically isolated buildings have unacceptable collapse performance due to either insufficient isolator displacement capacity or excessive inelastic structural deformations. The collapse performance and the overall performance could be improved by increasing the displacement capacity of the isolators and by limiting inelastic action in the superstructure while still providing ductile detailing. These observations may have been dependent on the modeling assumptions for the superstructure. This article investigates the effect of various modeling methods that are commonly used in research and design practice on the seismic performance of a six-story braced seismically isolated building with two different isolation systems, and a comparable nonisolated six-story building, all designed to meet the minimum criteria of ASCE 7-16. Performance measures considered in this study include story drift ratios, residual story drift ratios, floor accelerations, isolator horizontal displacement, and collapse. The study found that for seismically isolated buildings and for the modeling assumptions considered, only the inclusion of the effect of gravity frames has a beneficial effect of reducing the occurrence of small to moderate peak floor accelerations while there is insignificant effect on the other performance measures and particularly the computed probabilities of collapse in the MCE R . Also, the different modeling assumptions were found to have a more important effect on the seismic performance of nonisolated buildings than that of comparable seismically isolated buildings.

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Achieving targeted levels of reliability for low-rise seismically isolated structures

Cited by 15 publications

References 28 publications

A probabilistic design method to achieve targeted levels of reliability for seismically isolated structures

A probabilistic design method to achieve targeted levels of reliability for seismically isolated structures

Comparison of Design Spectra in Turkish Earthquake Codes (TEC and TBEC) in Terms of Seismic Isolator Design

Effect of superstructure modeling assumptions on the seismic performance of seismically isolated buildings

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