• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.336-336
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• 2002

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.35-42
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• 2012

We propose a probabilistic method to evaluate the uniform hazard spectra (UHS) of the soil of nuclear power plant(NPP) sites corresponding to that of a bedrock site. To do this, amplification factors on the surface of soil sites were estimated through site response analysis while considering the uncertainty in the earthquake ground motion and soil deposit characteristics. The amplification factors were calculated by regression analysis with spectral acceleration because these two factors are mostly correlated. The proposed method was applied to the evaluation of UHS for the KNGR (Korean Next Generation Reactor) and the APR1400 (Advanced Power Reactor 1400) nuclear power plant sites of B1, B4, C1 and C3. The most dominant frequency range with respect to the annual frequency of earthquakes was evaluated from the UHS analysis. It can be expected that the proposed method will improve the results of integrated risk assessments of NPPs rationally. We expect also that the proposed method will be applied to the evaluation of the UHS and of many other kinds of soil sites.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.1
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• pp.69-75
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• 2023

In Korea, most nuclear power plants were designed based on the design response spectrum of Regulatory Guide 1.60 of the NRC. However, in the case of earthquakes occurring in the country, the characteristics of seismic motions in Korea and the design response spectrum differed. The seismic motion in Korea had a higher spectral acceleration in the high-frequency range compared to the design response spectrum. The seismic capacity may be reduced when evaluating the seismic performance of the equipment with high-frequency earthquakes compared with what is evaluated by the design response spectrum for the equipment with a high natural frequency. Therefore, EPRI proposed the inelastic energy absorption factor for the equipment anchorage. In this study, the seismic performance of welding anchorage was evaluated by considering domestic seismic characteristics and EPRI's inelastic energy absorption factor. In order to reflect the characteristics of domestic earthquakes, the uniform hazard response spectrum (UHRS) of Uljin was used. Moreover, the seismic performance of the equipment was evaluated with a design response spectrum of R.G.1.60 and a uniform hazard response spectrum (UHRS) as seismic inputs. As a result, it was confirmed that the seismic performance of the weld anchorage could be increased when the inelastic energy absorption factor is used. Also, a comparative analysis was performed on the seismic capacity of the anchorage of equipment by the welding and the extended bolt.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1381-1382
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• 2004

• Earthquakes and Structures
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• v.17 no.3
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• pp.271-282
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• 2019

Knowing the response of buildings to earthquakes is very important in order to ensure that a structure is able to withstand a given level of ground shaking. Thus, nonlinear dynamic earthquake engineering analyses are unavoidable and are preferable procedure in the seismic assessment of buildings. In order to estimate seismic performance on the basis of the hazard at the site where the structure is located, the selection of appropriate seismic input is known to be a critical step while performing this kind of analysis. In this paper, seismic analysis is performed for a four-story reinforced concrete ISPRA frame structure which is designed according to Eurocode 8 (EC8). A total of 90 different earthquake scenarios were selected, 30 for each of three target spectrums, EC8 spectrum, Uniform Hazard Spectrum (UHS), and Conditional Mean Spectrum (CMS). The aim of this analysis was to evaluate the average maximum Inter-story Drift Ratio (IDR) for each target spectrum. Time history analysis for every earthquake record was obtained and, as a result, IDR as the main measure of damage were presented in order to compare with defined performance levels of reinforced concrete bare frames.

• Structural Engineering and Mechanics
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• v.37 no.2
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• pp.233-251
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• 2011

The seismic provisions of the current edition (2005) of the National Building Code of Canada (NBCC) differ significantly from the earlier edition. The current seismic provisions are based on the uniform hazard spectra corresponding to 2% probability of exceedance in 50 years, as opposed to the seismic hazard level with 10% probablity of exeedance in 50 years used in the earlier edition. Moreover, the current code is presented in an objective-based format where the design is performed based on an acceptable solution. In the light of these changes, an assessment of the expected performance of the buildings designed according to the requirements of the current edition of NBCC would be very useful. In this paper, the seismic performance of a set of six, twelve, and eighteen story buildings of regular geometry and with concrete moment resisting frames, designed for Vancouver western Canada, has been evaluated. Although the effects of non-structural elements are not considered in the design, the non-structural elements connected to the lateral load resisting systems affect the seismic performance of a building. To simulate the non-structural elements, infill panels are included in some frame models. Spectrum compatible artificial ground motion records and scaled actual accelerograms have been used for evaluating the dynamic response. The performance has been evaluated for each building under various levels of seismic hazard with different probabilities of exceedance. From the study it has been observed that, although all the buildings achieved the life-safety performance as assumed in the design provisions of the building code, their performance characteristics are found to be non-uniform.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.477-482
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• 1997

Safe shutdown earthquakes (SSE) of four existing nuclear power plant sites were evaluated by using a probabilistic method. It turned out that the SSE's of the two sites are smaller than those of the rest. Site-specific response spectra were developed for two sites of which SSE's show a comparatively large difference. The result shows that the site-specific response spectrum of one site is higher by a factor of 1.5 than that of the other. The comparison of uniform hazard spectrum and site-specific response spectrum at one of the two sites shows that the both spectra are consistent with each other.

• Earthquakes and Structures
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• v.11 no.4
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• pp.539-561
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• 2016

The rate of occurrence of intraplate earthquake events has been surveyed around the globe to ascertain the average level of intraplate seismic activities on land. Elastic response spectra corresponding to various levels of averaged (uniform) seismicity for a return period of 2475 years have then been derived along with modifying factors that can be used to infer ground motion and spectral response parameters for other return period values. Estimates derived from the assumption of uniform seismicity are intended to identify the minimum level of design seismic hazard in intraplate regions. The probabilistic seismic hazard assessment presented in the paper involved the use of ground motion models that have been developed for regions of different tectonic and crustal classifications. The proposed minimum earthquake loading model is illustrated by the case study of Peninsular Malaysia which has been identified with a minimum effective peak ground acceleration (EPGA) of 0.1 g for a return period of 2475 years, or 0.07 g for a notional return period of 475 years.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.87-97
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• 2009

The seismic site coefficients are often used with the seismic hazard maps to develop the design response spectrum at the surface. The site coefficients are most commonly developed deterministically, while the seismic hazarde maps are derived probabilistically. There is, hence, an inherent incompatibility between the two approaches. However, they are used together in the seismic design codes without a clear rational basis. To resolve the fundamental imcompatibility between the site coefficients and hazard maps, this study uses a novel probabilistic seismic hazard analysis (PSHA) technique that simulates the results of a standard PSHA at a rock outcrop, but integrates the site response analysis function to capture the site amplification effects within the PSHA platform. Another important advantage of the method is its ability to model the uncertainty, variability, and randomness of the soil properties. The new PSHA was used to develop fully probabilistic site coefficients for site classes of the seismic design code and another sets of site classes proposed in Korea. Comparisons highlight the pronounced discrepancy between the site coefficients of the seismic design code and the proposed coefficients, while another set of site coefficients show differences only at selected site classes.

• Earthquakes and Structures
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• v.14 no.4
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• pp.285-295
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• 2018

In this study, the effect of local site conditions (site class and site amplifications) and structural variability are investigated on fragility functions of typical building structures. The study area is chosen as Eastern Turkey. The fragility functions are developed using site-specific uniform hazard spectrum (UHS). The site-specific UHS is obtained based on simulated ground motions. The implementation of ground motion simulation into seismic hazard assessment has the advantage of investigating detailed local site effects. The typical residential buildings in Erzincan are represented by equivalent single degree of freedom systems (ESDOFs). Predictive equations are accomplished for structural seismic demands of ESDOFs to derive fragility functions in a straightforward manner. To study the sensitivity of fragility curves to site class, two sites on soft and stiff soil are taken into account. Two alternative site amplification functions known as generic and theoretical site amplifications are examined for these two sites. The reinforced concrete frames located on soft soil display larger fragilities than those on stiff soil. Theoretical site amplification mostly leads to larger fragilities than generic site amplification more evidently for reinforced concrete buildings. Additionally, structural variability of ESDOFs is generally observed to increase the fragility especially for rigid structural models.