• Title/Summary/Keyword: earthquake risk assessment

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Urban geology of Tabriz City: Environmental and geological constraints

  • Azarafza, Mohammad;Ghazifard, Akbar
    • Advances in environmental research
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    • v.5 no.2
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    • pp.95-108
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    • 2016
  • Urban geology is the study of urban geologic environments to provide a scientific basis for rational land use planning and urban development and provides information on geologic environments as a basis for city planners. Based on AEG recommendations, urban geological studies covered the urbanism and historical backgrounds, geological setting, engineering geological constraints and environmental assessments of understudied cities. The aim of this study is to provide a good view of urban geology of Tabriz city the capital of East Azerbaijan province in Iran. The topics of discussions about Tabriz city urban geology are included geologic (geomorphology, geology, climatology and hydrogeology), engineering geological (earthquake, landslide and geotechnical hazards investigations) and environmental characteristics (air, soil and water hazards assessment).The results of the urban geologic studies indicated that Tabriz city in terms of engineering geological and environmental constraints is at high risk potential and in terms of seismic activity and landslide instability is highly potential. In terms of air, soil and water pollution there are many important environmental concern in this city.

A Development of Tsunami Risk Assessment Model Using a Poisson-Pareto Distribution for Earthquake Frequency and Magnitude (지진발생빈도-크기 분석을 위한 Poisson-Pareto 분포 모형과 연계한 지진해일 위험도 평가 기법 개발)

  • Kim, Kwan-Hyuck;Kwon, Hyun-Han
    • Proceedings of the Korea Water Resources Association Conference
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    • 2017.05a
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    • pp.330-330
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    • 2017
  • 최근 우리나라 주변에 잦은 지진으로 인한 재해위험도 증가 우려가 커지고 있다. 국내 외에서 지진해일 위험도 평가는 시나리오를 기준으로 수치해석을 수행하고 이들 결과를 활용하는 절차로 수행된다. 그러나 위험도 평가는 하중조건 즉, 지진해일을 발생시키는 지진의 발생빈도 및 크기를 종합적으로 고려한 확률 계산이 우선적으로 요구되나, 기존 분석 절차에서는 고려가 되지 않거나 상대적으로 간략화 되어 진행되고 있다. 이러한 점에서 본 연구에서는 과거 우리나라 주변에 지진 및 지진해일 자료, 수치해석 모형 결과를 활용하여, 지진의 규모와 발생빈도를 종합적으로 고려할 수 있는 지진해일 위험도 평가 방법을 수립하고자 한다. 본 연구에서는 첫째, 지진 위험도 평가를 위해서 Poisson-Pareto 분포를 이용하였다. 둘째, 지진발생 위치 및 크기를 고려한 지진해일 위험도 평가 모형을 개발하였다. 셋째, 지진발생 위험도 및 지진해일 위험도를 통합한 해석 모형을 개발하고자 하며, 본 연구애서 제시하는 모든 해석 절차는 매개변수의 불확실성을 고려할 수 있도록 Bayesian 해석기법을 도입하여 진행하였다.

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Earthquake safety assessment of an arch dam using an anisotropic damage model for mass concrete

  • Xue, Xinhua;Yang, Xingguo
    • Computers and Concrete
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    • v.13 no.5
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    • pp.633-648
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    • 2014
  • The seismic safety of concrete dams is one of the important problems in the engineering due to the vast socio-economic disasters which may be caused by collapse of these infrastructures. The accuracy of the risk evaluation associated with these existing dams as well as the efficient design of future dams is highly dependent on a proper understanding of their behaviour due to earthquakes. This paper develops an anisotropic damage model for arch dam under strong earthquakes. The modified Drucker-Prager criterion is adopted as the failure criteria of the dynamic damage evolution of concrete. Some process fields and other necessary information for the safety evaluation are obtained. The numerical results show that the seismic behaviour of concrete dams can be satisfactorily predicted.

Evaluation of Liquefaction Potential for Soil Using Probabilistic Approaches (확률적 접근방법에 의한 지반의 액상화 가능성 평가)

  • Yi, Jin-Hak;Kwon, O-Soon;Park, Woo-Sun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5C
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    • pp.313-322
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    • 2006
  • Liquefaction of soil foundation is one of the major seismic damage types for infrastructures. In this paper, deterministic and probabilistic approaches for the evaluation of liquefaction potential are briefly summarized and the risk assessment method is newly proposed using seismic fragility and seismic hazard analyses. Currently the deterministic approach is widely used to evaluate the liquefaction potential in Korea. However, it is very difficult to handle a certain degree of uncertainties in the soil properties such as elastic modulus and resistant capacity by deterministic approach, and the probabilistic approaches are known as more promising. Two types of probabilistic approaches are introduced including (1) the reliability analysis (to obtain probability of failure) for a given design earthquake and (2) the seismic risk analysis of liquefaction for a specific soil for a given service life. The results from different methods show a similar trend, and the liquefaction potential can be more quantitatively evaluated using the new risk analysis method.

Seismic Risk Assessment of Extradosed Bridges with Lead Rubber Bearings (LRB 면진장치가 설치된 엑스트라도즈드교의 지진위험도 평가)

  • Kim, Doo Kie;Seo, Hyeong Yeol;Yi, Jin-Hak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1A
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    • pp.155-162
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    • 2006
  • This study presents the seismic risk assesment for an extradosed bridge with seismic isolators of lead rubber bearings(LRB). First, the seismic vulnerability of a structure and then the seismic hazard of the site are evaluated using earthquake data set and seismic hazard map in Korea, and then the seismic risk of the structure is assessed. The nonlinear seismic analyses are carried out to consider plastic hinges of bridge columns and nonlinear characteristics of soil foundation. The ductility demand is adopted to describe the nonlinear behavior of a column, and the moment-curvature curve of a column is assumed to be bilinear hysterestic. The fragility curves are represented as a log-normal distribution function for column damage, movement of superstructure, and cable yielding. And seismic hazard is estimated using the available seismic hazard maps. The results show that the effectiveness of the seismic isolators for the columns is more noticeable than those for cables and girders, in seismic isolated extradosed bridges under earthquakes.

Seismic vulnerability macrozonation map of SMRFs located in Tehran via reliability framework

  • Amini, Ali;Kia, Mehdi;Bayat, Mahmoud
    • Structural Engineering and Mechanics
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    • v.78 no.3
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    • pp.351-368
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    • 2021
  • This paper, by applying a reliability-based framework, develops seismic vulnerability macrozonation maps for Tehran, the capital and one of the most earthquake-vulnerable city of Iran. Seismic performance assessment of 3-, 4- and 5-story steel moment resisting frames (SMRFs), designed according to ASCE/SEI 41-17 and Iranian Code of Practice for Seismic Resistant Design of Buildings (2800 Standard), is investigated in terms of overall maximum inter-story drift ratio (MIDR) and unit repair cost ratio which is hereafter known as "damage ratio". To this end, Tehran city is first meshed into a network of 66 points to numerically locate low- to mid-rise SMRFs. Active faults around Tehran are next modeled explicitly. Two different combination of faults, based on available seismological data, are then developed to explore the impact of choosing a proper seismic scenario. In addition, soil effect is exclusively addressed. After building analytical models, reliability methods in combination with structure-specific probabilistic models are applied to predict demand and damage ratio of structures in a cost-effective paradigm. Due to capability of proposed methodology incorporating both aleatory and epistemic uncertainties explicitly, this framework which is centered on the regional demand and damage ratio estimation via structure-specific characteristics can efficiently pave the way for decision makers to find the most vulnerable area in a regional scale. This technical basis can also be adapted to any other structures which the demand and/or damage ratio prediction models are developed.

Probabilistic Safety Assessment of Gas Plant Using Fault Tree-based Bayesian Network (고장수목 기반 베이지안 네트워크를 이용한 가스 플랜트 시스템의 확률론적 안전성 평가)

  • Se-Hyeok Lee;Changuk Mun;Sangki Park;Jeong-Rae Cho;Junho Song
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.36 no.4
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    • pp.273-282
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    • 2023
  • Probabilistic safety assessment (PSA) has been widely used to evaluate the seismic risk of nuclear power plants (NPPs). However, studies on seismic PSA for process plants, such as gas plants, oil refineries, and chemical plants, have been scarce. This is because the major disasters to which these process plants are vulnerable include explosions, fires, and release (or dispersion) of toxic chemicals. However, seismic PSA is essential for the plants located in regions with significant earthquake risks. Seismic PSA entails probabilistic seismic hazard analysis (PSHA), event tree analysis (ETA), fault tree analysis (FTA), and fragility analysis for the structures and essential equipment items. Among those analyses, ETA can depict the accident sequence for core damage, which is the worst disaster and top event concerning NPPs. However, there is no general top event with regard to process plants. Therefore, PSA cannot be directly applied to process plants. Moreover, there is a paucity of studies on developing fragility curves for various equipment. This paper introduces PSA for gas plants based on FTA, which is then transformed into Bayesian network, that is, a probabilistic graph model that can aid risk-informed decision-making. Finally, the proposed method is applied to a gas plant, and several decision-making cases are demonstrated.

The development of the seismic fragility curves of existing bridges in Indonesia (Case study: DKI Jakarta)

  • Veby Citra Simanjuntak;Iswandi Imran;Muslinang Moestopo;Herlien D. Setio
    • Structural Monitoring and Maintenance
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    • v.10 no.1
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    • pp.87-105
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    • 2023
  • Seismic regulations have been updated from time to time to accommodate an increase in seismic hazards. Comparison of seismic fragility of the existing bridges in Indonesia from different historical periods since the era before 1990 will be the basis for seismic assessment of the bridge stock in Indonesia, most of which are located in earthquake-prone areas, especially those built many years ago with outdated regulations. In this study, seismic fragility curves were developed using incremental non-linear time history analysis and more holistically according to the actual strength of concrete and steel material in Indonesia to determine the uncertainty factor of structural capacity, βc. From the research that has been carried out, based on the current seismic load in SNI 2833:2016/Seismic Map 2017 (7% probability of exceedance in 75 years), the performance level of the bridge in the era before SNI 2833:2016 was Operational-Life Safety whereas the performance level of the bridge designed with SNI 2833:2016 was Elastic - Operational. The potential for more severe damage occurs in greater earthquake intensity. Collapse condition occurs at As = FPGA x PGA value of bridge Era I = 0.93 g; Era II = 1.03 g; Era III = 1.22 g; Era IV = 1.54 g. Furthermore, the fragility analysis was also developed with geometric variations in the same bridge class to see the effect of these variations on the fragility, which is the basis for making bridge risk maps in Indonesia.

Draft List and Relative Importance of Principal Processes in the Geosphere to be Considered for the Radiological Safety Assessment of the Domestic Geological Disposal Facility through Analyzing FEPs for KBS-3 Type Disposal Repository of High-level Radioactive Waste(HLW) (KBS-3 방식 고준위방폐물 심층처분장 FEP 분석을 통한 국내 사용후핵연료 심층처분시설 방사선학적 안전성 평가용 지권영역 주요 프로세스 항목 및 상대적 중요도 도출)

  • Sukhoon Kim;Donghyun Lee;Dong-Keuk Park
    • Journal of Radiation Industry
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    • v.17 no.1
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    • pp.33-44
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    • 2023
  • The deep geological repository of high-level radioactive waste shall be designed to meet the safety objective set in the form of radiation dose or corresponding risk to protect human and the environment from radiation exposure. Engineering feasibility and conformity with the safety objective of the facility conceptual design can be demonstrated by comparing the assessment result using the computational model for scenario(s) describing the radionuclide release and transport from repository to biosphere system. In this study, as the preliminary study for developing the high-level radioactive waste disposal facility in Korea, we reviewed and analyzed the entire list of FEPs and how to handle each FEP from a general point of view, which are selected for the geosphere region in the radiological safety assessment performed for the license application of the KBS-3 type deep geological repository in Finland and Sweden. In Finland, five FEPs (i.e., stress redistribution, creep, stress redistribution, erosion and sedimentation in fractures, methane hydrate formation, and salt exclusion) were excluded or ignored in the radionuclide release and transport assessment. And, in Sweden, six FEPs (i.e., creep, surface weathering and erosion, erosion/sedimentation in fractures, methane hydrate formation, radiation effects (rock and grout), and earth current) were not considered for all time frames and earthquake out of a total of 25 FEPs for the geosphere. Based on these results, an FEP list (draft) for the geosphere was derived, and the relative importance of each item was evaluated for conducting the radiological safety assessment of the domestic deep geological disposal facility. Since most of information on the disposal facility in Korea has not been determined as of now, it is judged that all FEP items presented in Table 3 should be considered for the radiological safety assessment, and the relative importance derived from this study can be used in determining whether to apply each item in the future.

Seismic fragility curves of single storey RC precast structures by comparing different Italian codes

  • Beilic, Dumitru;Casotto, Chiara;Nascimbene, Roberto;Cicola, Daniele;Rodrigues, Daniela
    • Earthquakes and Structures
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    • v.12 no.3
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    • pp.359-374
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    • 2017
  • The seismic events in Northern Italy, May 2012, have revealed the seismic vulnerability of typical Italian precast industrial buildings. The aim of this paper is to present a seismic fragility model for Italian RC precast buildings, to be used in earthquake loss estimation and seismic risk assessment by comparing two building typologies and three different codes: D.M. 3-03-1975, D.M. 16-01-1996 and current Italian building code that has been released in 2008. Based on geometric characteristics and design procedure applied, ten different building classes were identified. A Monte Carlo simulation was performed for each building class in order to generate the building stock used for the development of fragility curves trough analytical method. The probabilistic distributions of geometry were mainly obtained from data collected from 650 field surveys, while the material properties were deduced from the code in place at the time of construction or from expert opinion. The structures were modelled in 2D frameworks; since the past seismic events have identified the beam-column connection as the weakest element of precast buildings, two different modelling solutions were adopted to develop fragility curves: a simple model with post processing required to detect connection collapse and an innovative modelling solution able to reproduce the real behaviour of the connection during the analysis. Fragility curves were derived using both nonlinear static and dynamic analysis.