• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.926-939
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• 2022

The area of this study will cover the location-wise seismic response variation of an electrical cabinet in nuclear power point (NPP) based on classical reliability analysis. The location-based seismic ground motion (GM) selection is carried out with the help of probabilistic seismic hazard analysis using PSHRisktool, where the variation of reliability analysis can be understood from the relation between the reliability index and intensity measure. Two different approaches such as the first-order second moment method (FOSM) and Monte Carlo Simulation (MCS) are helped to evaluate and compare the reliability assessment of the cabinet. The cabinet is modeled with material uncertainty utilizing Steel01 as the material model and the fiber section modeling approach is considered to characterize the section's nonlinear reaction behavior. To verify the modal frequency, this study compares the FEM result with recorded data using Least-Squares Complex Exponential (LSCE) method from the impact hammer test. In spite of a few investigations, the main novelty of this study is to introduce the reader to check and compare the seismic reliability assessment variation in different seismic locations and for different earthquake levels. Alongside, the betterment can be found by comparing the result between two considered reliability estimation methods.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.10a
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• pp.41-48
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• 1997

The seismic risk in Seoul Metropolitan Area(latitude 37.0$^{\circ}$~37.8$^{\circ}$, longitude 126.5$^{\circ}$~127.5$^{\circ}$)based on all Korean earthquake data of Modified Mercalli Intensity equal to or greater than V is evaluated by extreme value method and point source method. The seismic risk estimated from all data turned out to be lower than from the data since the Chosen dynasty during which seismic data appear to be rather complete. The damaging earthquake of park horizontal ground acceleration grater than 0.1g turns out to occur with 90% probability of being exceeded in 200 years when the data since the Chosen Dynasty are used.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.278-287
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• 2000

In Korea, countermeasures against earthquake disasters such as the seismic performance evaluation and/or retrofit scheme of buildings have not been fully performed since Korea had not been experienced many destructive earthquakes in the past. However, due to more than four hundred earthquakes with slight/medium intensity occurred in the off-coastal and inland of Korea during the past 20 years, and due to the great earthquakes occurred recently in neighboring countries, such as the 1995 Hyogoken-Nambu Earthquake with more than 6,500 fatalities in Japan and the 1999 Ji-Ji Earthquake with more than 2,500 fatalities in Taiwan, the importance of the future earthquake preparedness measures in Korea is highly recognized. The main objective of this paper is to provide the basic data for development of a methodology for the future earthquake preparedness in Korea by investigating the concept and applicabilities of the Japanese Standard for Evaluation of Seismic Performance of Existing RC Buildings developed in Japan among the methodologies of all over the world. In this paper, a seismic performance evaluation method of the existing reinforced concrete buildings is proposed based on experimental data of columns and walls carried out in Korea by referring the Japanese Standard, especially focusing on the Strength Index(C) among the indices in the seismic capacity index(IS) equations. Also, the seismic capacities of two existing reinforced concrete buildings in Korea are evaluated based on the proposed methodology and the Japanese Standard, and the correlations between the seismic capacities by the proposed methodology and the Japanese Standard are discussed.

• Structural Engineering and Mechanics
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• v.86 no.4
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• pp.547-571
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• 2023

To deeply probe the actual earthquake level and fragility of typical reinforced concrete (RC) structures under multiple intensity grades, considering diachronic measurement building stock samples and actual observations of representative catastrophic earth shocks in China from 1990 to 2010, RC structures were divided into traditional RC structures (TRCs) and bottom reinforced concrete frame seismic wall masonry (BFM) structures, and the empirical damage characteristics and mechanisms were analysed. A great deal of statistics and induction were developed on the historical experience investigation data of 59 typical catastrophic earthquakes in 9 provinces of China. The database and fragility matrix prediction model were established with TRCs of 4,122.5284×104 m² and 5,844 buildings and BFMs of 5,872 buildings as empirical seismic damage samples. By employing the methods of structural damage probability and statistics, nonlinear prediction of seismic vulnerability, and numerical and applied functional analysis, the comparison matrix of actual fragility probability prediction of TRC and BFM in multiple intensity regions under the latest version of China's macrointensity standard was established. A novel nonlinear regression prediction model of seismic vulnerability was proposed, and prediction models considering the seismic damage ratio and transcendental probability parameters were constructed. The time-varying vulnerability comparative model of the sample database was developed according to the different periods of multiple earthquakes. The new calculation method of the average fragility prediction index (AFPI) matrix parameter model has been proposed to predict the seismic fragility of an areal RC structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.119-130
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• 2009

Seismic fragility curves of a structure represent the probability of exceeding the prescribed structural damage state for a given various levels of ground motion intensity such as peak ground acceleration (PGA), spectral acceleration ($S_a$) and spectral displacement ($S_d$). So those are very essential to evaluate the structural seismic performance and seismic risk. The purpose of this paper is to develop seismic fragility curves for PSC box girder bridges. In order to construct numerical fragility curve of bridge structure using nonlinear time history analysis, a set of ground motions corresponding to design spectrum are artificially generated. Assuming a lognormal distribution, the fragility curve is estimated by using the methodology proposed by Shinozuka et al. PGA is simple and generally used parameter in fragility curve as ground motion intensity. However, the PGA has not good relationship with the inelastic structural behavior. So, $S_a$ and $S_d$ with more direct relationship for structural damage are used in fragility analysis as more useful intensity measures instead of PGA. The numerical fragility curves based on nonlinear time history analysis are compared with those obtained from simple method suggested in HAZUS program.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.147-155
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• 2015

A new SRCF (Steel Reinforced Concrete Frame) external connection method for seismic strengthening of medium-and low-rise reinforced concrete buildings is reported in this paper. The SRCF method, proposed in this study, is capable of carrying out the seismic retrofitting construction while residents can live inside building. The method is one of the strength design approach by retrofit which can easily increase the ultimate lateral load capacity of concrete buildings controlled by shear. The pseudo-dynamic test, designed using a existing school building in Korea, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and deformation. Test results revealed that the proposed SRCF strengthening method installed in RC frame enhanced conspicuously the strength and deformation capacities, and the method can resist markedly under the large scaled earthquake intensity level.

• KCI Concrete Journal
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• v.13 no.2
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• pp.26-32
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• 2001

A simple expected damage cost model is developed and a systematic approach to evaluate the economic effects of seismic hazards to reinforced concrete structures is presented. An expected damage cost function during a specific lifetime is modeled by a Poisson's process with uniform continuous cash flow assumption. It is possible that the proposed method can decouple the damage cost effect from random earthquake events. Thus, expected damage cost function can be formulated as a combination of three independent terms; a present worth factor of Poisson's process, a damage cost interpolation function and a mean occurrence rate of earthquake intensity. The validity of the proposed method is demonstrated by a comparative study of LCC evaluations with the previous study.

• Geophysics and Geophysical Exploration
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• v.13 no.3
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• pp.219-226
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• 2010

Current earthquake alert notification for immediate post-earthquake procedures for the critical facilities is exclusively dependent on the ground-motion intensity measures observed at the seismic station located within the site. This practice is prune to false notification due to a noise and problems of missing and poor quality records of the seismic station. The credibility of the earthquake alert notification can be enhanced by utilizing the multiple transformed records of the nearby seismic stations at other sites interconnected to the same earthquake monitoring system by a network. The time-domain transformation of the site-response between the seismic stations is implemented by convoluting the nearby records with a pair of forward and inverse FIR filters designed for the site response relative to a seismic basement. The transformed records from the nearby seismic stations can be used to estimate the ground-motion intensity measures missing at the site or to evaluate the data quality along with other various possible applications in the area of geoscience and earthquake engineering.

• Earthquakes and Structures
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• v.17 no.6
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• pp.557-566
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• 2019

The evaluation of the seismic hazard for a given site is to estimate the seismic ground motion at the surface. This is the result of the combination of the action of the seismic source, which generates seismic waves, the propagation of these waves between the source and the site, and site local conditions. The aim of this work is to evaluate the sensitivity of dynamic response of extended structures to spatial variable ground motions (SVGM). All factors of spatial variability of ground motion are considered, especially local site effect. In this paper, a method is presented to simulate spatially varying earthquake ground motions. The scheme for generating spatially varying ground motions is established for spatial locations on the ground surface with varying site conditions. In this proposed method, two steps are necessary. Firstly, the base rock motions are assumed to have the same intensity and are modelled with a filtered Tajimi-Kanai power spectral density function. An empirical coherency loss model is used to define spatial variable seismic ground motions at the base rock. In the second step, power spectral density function of ground motion on surface is derived by considering site amplification effect based on the one dimensional seismic wave propagation theory. Several dynamics analysis of a curved viaduct to various cases of spatially varying seismic ground motions are performed. For comparison, responses to uniform ground motion, to spatial ground motions without considering local site effect, to spatial ground motions with considering coherency loss, phase delay and local site effects are also calculated. The results showed that the generated seismic signals are strongly conditioned by the local site effect. In the same sense, the dynamic response of the viaduct is very sensitive of the variation of local geological conditions of the site. The effect of neglecting local site effect in dynamic analysis gives rise to a significant underestimation of the seismic demand of the structure.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.6
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• pp.11-25
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• 2009

A method of instrumentally estimating the seismic intensity (MMI) based on Fourier Acceleration Spectrum, which is the so-called 'FAS MMI method' of Sokolov and Wald (2002), was considered for its applicability to Korea. In order to implement the FAS MMI method, the empirical models of mean (m) and standard deviation (${\sigma}$) for Korea were derived for MMI ${\leq}$ IV according to individual seismic intensity by using the site-consistent horizontal FAS of 580 records from 65 isoseismal maps prepared based on the reported MMI of Korea Meteorological Administration. The site-consistent FAS at a site were obtained by correcting the observed FAS for the difference of the site amplification function relative to that of the target site of Class D station (Yun and Suh, 2007) which was evaluated to be a representative site for the generic soil profile of Korea. The FAS m model for MMI ${\leq}$ IV follows the overall linear relation in log space according to seismic intensities, featuring the FAS mean model for MMI = IV similar to that of the global model of Sokolov and Wald (2002). The ${\sigma}$-values of the FAS model are found to be greater than those of the global model for MMI ${\geq}$ V, while significantly lower than those of the global model for MMI = IV.