Non-Ergodic Site Response in Seismic Hazard Analysis

Stewart, Jonathan P.; Afshari, Kioumars; Goulet, Christine A.

doi:10.1193/081716eqs135m

Cited by 90 publications

(55 citation statements)

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“…We prefer the use of empirical model trends to guide our extrapolation here rather than simulation results due to difficulties in modeling site response with 1D GRA at long periods (e.g. Stewart et al, 2017a). For V 1 , we maintain the value at 5.0 s for longer periods.…”

Section: Fv Model Developmentmentioning

confidence: 99%

Ergodic site amplification model for central and eastern North America

et al. 2020

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The United States Geological Survey national seismic hazard maps have historically been produced for a reference site condition of VS30 = 760 m/s. For other site conditions, site factors are used, which heretofore have been developed using ground motion data and simulations for shallow earthquakes in active tectonic regions. Research results from the Next Generation Attenuation–East (NGA-East) project, as well as previous and contemporaneous related research, demonstrate different levels of site amplification in central and eastern North America (CENA) as compared to active regions. We provide recommendations for modeling of ergodic site amplification in CENA based primarily on research results from the literature. The recommended model has three additive terms in natural logarithmic units. Two describe linear site amplification: an empirically constrained VS30-scaling term relative to a 760 m/s reference and a simulation-based term to adjust site amplification from the 760 m/s reference to the CENA reference of VS = 3000 m/s. The third term is a nonlinear model that is described in a companion document. All median model components are accompanied by epistemic uncertainty models.

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Section: Fv Model Developmentmentioning

confidence: 99%

Ergodic site amplification model for central and eastern North America

et al. 2020

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“…Let us assume that the uncertainty in the ground motion representation, manifesting itself as the record‐to‐record variability in structural response given the seismic intensity level, is the only source of uncertainty (neglecting modelling uncertainties). Then, neglecting the non ergodicity in seismic hazard assessment, deterioration in structural properties due to aging, and assuming that the damaged structure is always restored to the same intact structure, the LS excursion can be described by a homogenous Poisson distribution. Therefore, Equations and can be used to calculate the structural reliability.…”

Section: Reliability Assessmentmentioning

confidence: 99%

Seismic reliability assessment and the nonergodicity in the modelling parameter uncertainties

Jalayer

Ebrahimian

2020

Earthq Engng Struct Dyn

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Summary Modelling uncertainty can significantly affect the structural seismic reliability assessment. However, the limit state excursion due to this type of uncertainty may not be described by a Poisson process as it lacks renewal properties with the occurrence of each earthquake event. Furthermore, considering uncertainties related to ground motion representation by employing recorded ground motions together with modelling uncertainties is not a trivial task. Robust fragility assessment, proposed previously by the authors, employs the structural response to recorded ground motion as data in order to update prescribed seismic fragility models. Robust fragility can be extremely efficient for considering also the structural modelling uncertainties by creating a dataset of one‐to‐one assignments of structural model realizations and as‐recorded ground motions. This can reduce the computational effort by more than 1 order of magnitude. However, it should be kept in mind that the fragility concept itself is based on the underlying assumption of Poisson‐type renewal. Using the concept of updated robust reliability, considering both the uncertainty in ground motion representation based on as‐recorded ground motion and non ergodic modelling uncertainties, the error introduced through structural reliability assessment by using the robust fragility is quantified. It is shown through specific application to an existing RC frame that this error is quite small when the product of the time interval and the standard deviation of failure rate is small and is on the conservative side.

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“…This assumption overlooks the site-specific geologies that can influence earthquake ground motion characteristics. While efforts are underway [5][6][7] to develop nonergodic GMMs to better capture local geologic features, their development is limited by the scarcity of strong ground motion records.…”

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Tall building performance‐based seismic design using SCEC broadband platform site‐specific ground motion simulations

Zhong

Lin

Deierlein

et al. 2020

Earthq Engng Struct Dyn

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The scarcity of strong ground motion records presents a challenge for making reliable performance assessments of tall buildings whose seismic design is controlled by large-magnitude and close-distance earthquakes. This challenge can be addressed using broadband ground-motion simulation methods to generate records with site-specific characteristics of large-magnitude events. In this paper, simulated site-specific earthquake seismograms, developed through a related project that was organized through the Southern California Earthquake Center (SCEC) Ground Motion Simulation Validation (GMSV) Technical Activity Group, are used for nonlinear response history analyses of two archetype tall buildings for sites in San Francisco, Los Angeles, and San Bernardino. The SCEC GMSV team created the seismograms using the Broadband Platform (BBP) simulations for five site-specific earthquake scenarios. The two buildings are evaluated using nonlinear dynamic analyses under comparable record suites selected from the simulated BBP catalog and recorded motions from the NGA-West database. The collapse risks and structural response demands (maximum story drift ratio, peak floor acceleration, and maximum story shear) under the BBP and NGA suites are compared. In general, this study finds that use of the BBP simulations resolves concerns about estimation biases in structural response analysis which are caused by ground motion scaling, unrealistic spectral shapes, and overconservative spectral variations. While there are remaining concerns that strong coherence in some kinematic fault rupture models may lead to an overestimation of velocity pulse effects in the BBP simulations, the simulations are shown to generally yield realistic pulse-like features of near-fault ground motion records.

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Non-Ergodic Site Response in Seismic Hazard Analysis

Cited by 90 publications

References 50 publications

Ergodic site amplification model for central and eastern North America

Ergodic site amplification model for central and eastern North America

Seismic reliability assessment and the nonergodicity in the modelling parameter uncertainties

Tall building performance‐based seismic design using SCEC broadband platform site‐specific ground motion simulations

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