Assessing the Collapse Probability of Base-Isolated Buildings considering Pounding to Moat Walls using the FEMA P695 Methodology

Masroor, A.; Mosqueda, Gilberto

doi:10.1193/092113eqs256m

Cited by 38 publications

(26 citation statements)

References 19 publications

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“…If isolator device is tested following test specification regulated in ASCE 7-16 as well as existing manufacture qualification control program and standard, and test results indicate stable hysteresis behavior and required capacities for the isolation system, it is recommended to use β TD = 0.1–0.2 (FEMA, 2009; Masroor and Mosqueda 2015). If the prototype isolator testing program and the quality of isolator specimen are not well documented or the behavior of isolator device, especially under extreme displacement range is not well understood, a larger β TD value should be used.…”

Section: Determination Of System Uncertainty βTotmentioning

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%

“…A 3D numerical model of the BI-IMRF was developed in OpenSees (Masroor and Mosqueda, 2013). The study uses the nonlinear version of this model for conducting IDA and modifies the superstructure to be elastic for determining isolator capacities following the proposed procedure.…”

Section: Design Example Considering the Proposed Proceduresmentioning

confidence: 99%

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

Shao

Mahin

2020

Earthquake Spectra

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“…5,6 Moat wall pounding can induce very large accelerations and drift demands, diminishing the effectiveness of the isolation system. [7][8][9][10][11] Figure 1 shows prototypical deformation patterns for three types of buildings: a traditional fixedbased building, a base-isolated building with no impact, and a base-isolated building with impact. In general, a baseisolated building will behave like a rigid body if there is no impact.…”

Section: Introductionmentioning

confidence: 99%

“…If impact occurs, however, the structure temporarily loses the isolation benefits and will undergo deformations akin to a fixed-based building. Recent studies 9,[12][13][14] indicate that if the moat wall clearance is not sufficiently large, or if the isolation system is not adequately restrained, the probability of collapse of a base isolated building exceeds the limitations targeted by current design standards.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of uniaxial contact models for moat wall pounding simulations

Hughes

Mosqueda

2020

Earthq Engng Struct Dyn

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Summary Moat wall pounding occurs when a base‐isolated building displaces beyond the provided clearance and collides with the surrounding retaining wall, inducing very high floor accelerations and interstory drifts. Previous studies on moat wall pounding typically employ simplified models of the superstructure, with a uniaxial contact spring used to model the entire moat wall. Consequently, researchers have developed sophisticated contact models to estimate the normal‐direction contact force that is generated during seismic pounding. This study examines how the choice in contact model affects the seismic response of a base‐isolated building subjected to impact‐inducing ground excitation. Five widely used state‐of‐the‐art contact models are summarized and implemented into an experimentally‐calibrated numerical model of a base‐isolated moment frame. Results of nonlinear dynamic time history analyses are shown in detail for one ground motion, followed by a larger parametric study across 28 near‐fault ground motions. This work shows that peak impact force and base acceleration are moderately sensitive to the choice in contact model, while upper floor accelerations and interstory drifts are practically not affected.

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“…They found that the forces from moat impact amplified story drift and accelerations responses and could induce yielding in the superstructure, although no collapse was observed in the testing. Using a model for the moat impact developed from their experimental testing, Masroor and Mosqueda looked at the collapse probability of braced and moment frame buildings, with general bilinear isolators. Cutfield et al looked at the same braced frame structure with the included moat impact to investigate the effect of moat impact on life cycle cost.…”

Section: Introductionmentioning

confidence: 99%

Extreme behavior in a triple friction pendulum isolated frame

Becker

Bao

Mahin

2017

Earthq Engng Struct Dyn

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Summary While isolation can provide significantly enhanced performance compared to fixed‐base counter parts in design level or even maximum considered level earthquakes, there is still uncertainty over the performance of isolation systems in extreme events. Researchers have looked at component level stability of rubber bearings and on the effect of moat impact on behavior of structures isolated on general bilinear isolators. However, testing of triple friction pendulum (TFP) sliding bearings has not been done dynamically or incorporated into a building system. Here, one‐third scale laboratory tests were conducted to on a 2‐story 2‐bay TFP‐isolated structure. Input motions were increasingly scaled until failure occurred at the isolation level. As the superstructure was designed with a yield force equivalent to the force of the bearing just at their ultimate displacement capacity, there was minimal yielding. A numerical model is presented to simulate the isolated building up to and including bearing failure. Forces transferred to the superstructure in extreme motions are examined using both experimental and numerical data. Additionally, the effect of the hardening stage of the TFP bearing is evaluated using the numerical model, finding slight benefits.

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Assessing the Collapse Probability of Base-Isolated Buildings considering Pounding to Moat Walls using the FEMA P695 Methodology

Cited by 38 publications

References 19 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

Evaluation of uniaxial contact models for moat wall pounding simulations

Extreme behavior in a triple friction pendulum isolated frame

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