• Earthquakes and Structures
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• 제13권3호
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• pp.323-335
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• 2017

A simplified framework for the probabilistic estimation of economic losses induced by the structural vulnerability in single-story and single-bay precast industrial buildings is presented. The simplifications introduced in the framework are oriented to the definition of an expeditious procedure adoptable by government agencies and insurance companies for preliminary risk assessment. The economic losses are evaluated considering seismic hazard, structural response, damage resulting from the structural vulnerability and only structural-vulnerability-induced e]conomic losses, i.e., structural repair or reconstruction costs (stock and flow costs) and content losses induced by structural collapse. The uncertainties associated with each step are accounted for via Monte Carlo simulations. The estimation results in a probabilistic description of the seismic risk of portal-like industrial buildings, expressed in terms of economic losses for each occurrence (i.e., seismic event) that owners (i.e., insured) and stakeholders can use to make risk management decisions. The outcome may also be useful for the definition of the insurance premiums and the evaluation of the risks and costs for the owner corresponding to the insurance industrial costs. A prototype of a precast concrete industrial building located in Mirandola, Italy, hit by the 2012 Emilia earthquake, is used as an example of the application of the procedure.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.597-604
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• 2006

The seismic safety of the prestressed concrete containment building was evaluated by the seismic fragility analysis based on the nonlinear dynamic time-history analyses. Four kinds of earthquake ground motions were used for the seismic fragility analysis of the containment building to consider the potential earthquake hazard. The conventional seismic fragility analysis of the safety related structures in nuclear pouter plant have been performed by using the linear elastic analysis results for the seismic design. In this study, the displacement based seismic fragility analysis method was proposed.

• Earthquakes and Structures
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• 제24권4호
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• pp.303-316
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• 2023

Rapid post-earthquake damage estimation of subway stations is particularly necessary to improve short-term crisis management and safety measures of urban subway systems after a destructive earthquake. The conventional Performance-Based Earthquake Engineering (PBEE) framework with constant earthquake occurrence rate is invalid to estimate the aftershock risk because of the time-varying rate of aftershocks and the uncertainty of mainshock-damaged state before the occurrence of aftershocks. This study presents a time-varying probabilistic seismic risk assessment framework for underground structures considering mainshock and aftershock hazards. A discrete non-omogeneous Markov process is adopted to quantify the time-varying nature of aftershock hazard and the uncertainties of structural damage states following mainshock. The time-varying seismic risk of a typical rectangular frame subway station is assessed under mainshock-only (MS) hazard and mainshock-aftershock (MSAS) hazard. The results show that the probabilities of exceeding same limit states over the service life under MSAS hazard are larger than the values under MS hazard. For the same probability of exceedance, the higher response demands are found when aftershocks are considered. As the severity of damage state for the station structure increases, the difference of the probability of exceedance increases when aftershocks are considered. PSDR=1.0% is used as the collapse prevention performance criteria for the subway station is reasonable for both the MS hazard and MSAS hazard. However, if the effect of aftershock hazard is neglected, it can significantly underestimate the response demands and the uncertainties of potential damage states for the subway station over the service life.

• Earthquakes and Structures
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• 제19권6호
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• pp.471-484
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• 2020

Previous earthquakes show that, structural safety evaluations should include the evaluation of nonstructural components. Failure of nonstructural components can affect the operational capacity of critical facilities, such as hospitals and fire stations, which can cause an increase in number of deaths. Additionally, failure of nonstructural components may result in economic, architectural, and historical losses of community. Accelerations and random vibrations must be under the predefined limitations in structures with high technological equipment, data centers in this case. Failure of server equipment and anchored server racks are investigated in this study. A probabilistic study is completed for a low-rise rigid sample structure. The structure is investigated in two versions, (i) conventional fixed-based structure and (ii) with a base isolation system. Seismic hazard assessment is completed for the selected site. Monte Carlo simulations are generated with selected parameters. Uncertainties in both structural parameters and mechanical properties of isolation system are included in simulations. Anchorage failure and vibration failures are investigated. Different methods to generate fragility curves are used. The site-specific annual hazard curve is used to generate risk curves for two different structures. A risk matrix is proposed for the design of data centers. Results show that base isolation systems reduce the failure probability significantly in higher floors. It was also understood that, base isolation systems are highly sensitive to earthquake characteristics rather than variability in structural and mechanical properties, in terms of accelerations. Another outcome is that code-provided anchorage failure limitations are more vulnerable than the random vibration failure limitations of server equipment.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.28-34
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• 2002

The b-value in the magnitude-frequency relationship logN(m) = $\alpha$ - bmwhere N(m) is the number of earthquakes exceeding magnitude m, is important seismicity parameter In hazard analysis. Estimation of the b-value for earthquake data observed on KSRS array network is done employing the maximum likelihood technique. Assuming the whole Korea Peninsula as a single seismic source area, the b-value is computed at 0.9. The estimation for KMA earthquake data is also similar to that. Since estimate is a function of minimum magnitude, we can inspect the completeness of earthquake catalog in the fitting process of b-value. KSRS and KMA data lists are probably incomplete for magnitudes less than 2.0 and 3.0, respectively. Examples from probabilistic seismic hazard assessment calculated for a range of b-value show that the small change of b-value has seriously effect on the prediction of ground motion.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2010년도 정기 학술발표대회
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• pp.16-24
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• 2010

This paper introduces the applications of Taiwan Earthquake Loss Estimation System (TELES), which is developed by the National Center for Research on Earthquake Engineering (NCREE). Seismic disaster simulation technology (SDST) integrates geographical information system to assess the distribution of ground shaking intensity, ground failure probability, building damages, casualties, post-quake fires, debris, lifeline interruptions, economic losses, etc. given any set of seismic source parameters. The SDST may integrate with Taiwan Rapid Earthquake Information Release System (TREIRS) developed by Central Weather Bureau (CWB) to obtain valuable information soon after large earthquakes and to assist in decision-making processes to dispatch rescue and medical resources more efficiently. The SDST may also integrate with probabilistic seismic source model to evaluate various kinds of risk estimates, such as average annual loss, probable maximum loss in one event, and exceeding probability curves of various kinds of losses, to help proposing feasible countermeasures and risk management strategies.

• Nuclear Engineering and Technology
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• 제54권3호
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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.

• 한국전산구조공학회논문집
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• 제37권3호
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• pp.205-216
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• 2024

최근 원자력 지진 PSA(Probabilistic Safety Assessment)를 토대로 산업시설물의 지진 PSA를 수행하는 연구가 진행되었다. 해당 연구는 원자력 발전소와 산업시설물의 차이를 파악하고, 최종적으로 운영정지를 목표로 하는 고장수목(Fault Tree)를 구축한 후 시각적 확률도구인 베이지안 네트워크(Bayesian Network, BN)으로 변환하였다. 본 연구는 선행연구를 기반으로 지진으로 유발된 구조손상으로 인해 발생 가능한 화재･폭발에 대해 PSA를 수행하고자 하였다. 이를 위해 화재･폭발을 사건수목(Event Tree)으로 표현하고, BN으로 변환하였다. 변환된 BN은 화재･폭발 모듈로서 선행연구에서 제시된 고장수목 기반 BN과 연계되어 최종적으로 지진 유발 화재･폭발 PSA를 수행할 수 있는 BN 기반 방법론이 개발되었다. 개발된 BN을 검증하기위해 수치예제로서 가상의 가스플랜트 Plot Plan을 생성하였고, 가스플랜트의 설비 종류가 구체적으로 반영된 대규모 BN을 구축하였다. 해당 BN을 이용하여 지진 규모에 따른 전체시스템의 운영정지 확률 및 하위시스템들의 고장확률 산정과 더불어 역으로 전체시스템이 운영 정지되었을 때 하위시스템들의 영향도 분석과 화재･폭발 가능성을 산정하여 다양한 의사결정을 수행할 수 있음을 제시함으로써 그 우수성을 확인하였다.

• 한국전산구조공학회논문집
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• 제27권6호
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• pp.517-524
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• 2014

구조물의 내용연수 동안 예상되는 지진에 대한 피해와 손실을 최소화하는 것이 내진설계의 최종적인 목표로 볼 수 있다. 이러한 목표를 만족시키기 위한 개념으로 지진하중에 대한 구조물의 손상확률을 나타내는 지진취약도를 작성하여 지진에 대한 구조물의 확률론적 성능평가를 수행한 후, 해당 지역에서 발생 가능한 지진에 대한 연간 초과확률로 표현되는 지진위험도를 활용하여 연간 손실 발생확률을 산정하는 절차를 제시한다. 본 연구는 미국 강진지역의 지진하중을 고려하여 설계된 철골모멘트골조에 대해 취약도를 정량적으로 평가하고 연간 손실 발생확률을 예측하다. 또한 HAZUS의 철골모멘트골조 대표건축물에 대한 손실 평가결과를 비교하였으며, 그 결과 HAZUS에 의한 연간손실이 보수적으로 산정됨을 알 수 있었다. 제시된 방법으로부터 해당 구조물의 내진성능 및 연간 손실 평가를 할 수 있으며, 향후 관련 연구에 활용할 수 있을 것으로 판단된다.

• 대한토목학회논문집
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• 제26권5C호
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• pp.313-322
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• 2006

지반 액상화는 대표적인 지진 피해의 한 형태로 이 연구에서는 이러한 지반 액상화 가능성 평가를 위한 확률적 접근 방법을 제시하였다. 일정한 사용기간 동안의 지진에 의한 액상화 발생확률을 구하기 위하여 액상화 취약도와 지진재해도를 결합하여 액상화 위험도를 산정할 수 있도록 하였다. 현재 국내에서는 결정론적인 방법이 많이 이용되고 있으나, 이러한 방법은 지반 물성치에 포함되어 있는 많은 불확실성을 합리적으로 다루기 어려운 단점이 있다. 두 가지 형태의 확률적 접근 방법을 제시하였는데, 첫번째는 설계지진에 대한 확률적 신뢰도 해석 방법이고, 두번째는 주어진 지반조건에 대하여 일정한 사용기간 동안 액상화가 발생할 수 있는 가능성을 평가한 위험도 해석 방법이다. 기존의 결정론적 방법과 확률적 방법에 의하여 매립지반의 액상화를 평가하였으며, 위험도 해석에 의한 액상화 가능성 평가기법을 지속적으로 적용하고, 설계기준이 제시된다면 보다 합리적이고, 정량적인 지반 액상화 가능성 평가기법이 될 수 있음을 검증하였다.