• Structural Engineering and Mechanics
• /
• 제48권2호
• /
• pp.207-220
• /
• 2013

In this study, the vulnerability of two existing asymmetric steel building frames to Progressive Collapse (PC) is assessed. The buildings have different frame systems, steel sections and number of stories (nine and six). An alternate path method (APM) with a linear static analysis (LS) is carried out according to General Services Administration (GSA) 2003 guidelines. The Demand Capacity Ratio (DCR) of each primary element (beams and columns) is given with its specific details for all frames. The results show that the nine-story building with a dual frame system (moment frame with bracing system) has a lower susceptibility and greater resistance to PC than the six-story building with a simple building frame system (gravity system with bracing system). Implementing built-up box-shaped sections for columns is a better choice than using built-up I-shaped sections because there is no weak axis for the box section.

• 한국수자원학회논문집
• /
• 제52권10호
• /
• pp.729-742
• /
• 2019

국내의 자연재해피해 중 가장 큰 부분을 대부분은 매년 여름철에 발생하고 있는 태풍과 장마로 인한 침수피해이므로, 도시 홍수에 대한 관심은 꾸준히 증가하고 있다. 반복되는 피해 저감을 위해 다양한 방법으로 홍수취약성을 분석하지만, 반복되는 도시(재)개발로 인해 지형 및 사회경제적인 요인들이 바뀌고 있어, 기존에 실시했던 홍수취약성 분석결과가 현실적으로 반영이 되기 힘든 상태이다. 이에 홍수피해 예방을 위해 변형된 지형과 환경에 맞춰 새로운 홍수취약성 분석을 실시하여 지역의 투자 우선순위를 파악할 필요가 있다. 본 연구에서는 우리나라 중 가장 도시화가 된 서울시 25개 구를 대상지역으로 선정하였으며, 홍수취약성 인자들을 Pressure-State-Response (PSR) 구조로 구분하였다. 압력지수(PI)는 인구밀도, 차량 수 등 9개의 인자를, 상태지수(SI)는 공공시설 피해액 등 4개의 인자를 선정하였으며, 대책지수(RI)는 대피시설 수, 재정자립도 등 7개의 인자를 선택하여 홍수취약성지수를 계산하였다. 각 인자들의 가중치를 계산하기 위해 AHP 방법과 Fuzzy이론을 결합한 Fuzzy AHP 방법을 적용하였다. 그 결과, 세부지수인 압력지수나 대책지수는 가중치 결정방법에 따라 숫자가 변하기는 하지만, 순위 변화는 없었으며, 상태지수는 값 뿐만 아니라 순위에도 다소 변화가 있었다. 또한 세부지수들을 결합하여 계산한 홍수취약성지수는 Fuzzy AHP 방법으로 계산하였을 경우, 강남 지역의 취약성이 눈에 띄게 감소하였다. 이는 강남지역의 홍수피해복구금액이나 재정자립도가 높고, 다른 지자체와 차이가 크기 때문에 Fuzzy 수를 이용하여 불확실성을 고려할 경우 취약성이 낮아진 것으로 분석된다.

• Earthquakes and Structures
• /
• 제21권6호
• /
• pp.627-639
• /
• 2021

Fragility curves are being more significant as a useful tool for evaluating the relationship between the earthquake intensity measure and the effects of the engineering demand parameter on the buildings. In this paper, the effect of different site conditions on the vulnerability of the structures was examined through the fragility curves taking into account different strength capacities of the precast columns. Thus, typical existing single-story precast RC industrial buildings which were built in Turkey after the year 2000 were examined. The fragility curves for the three typical existing industrial structures were derived from an analytical approach by performing non-linear dynamic analyses considering three different soil conditions. The Park and Ang damage index was used in order to determine the damage level of the members. The spectral acceleration (Sa) was used as the ground motion parameter in the fragility curves. The results indicate that the fragility curves were derived for the structures vary depending on the site conditions. The damage probability of exceedance values increased from stiff site to soft site for any Sa value. This difference increases in long period in examined buildings. In addition, earthquake demand values were calculated by considering the buildings and site conditions, and the effect of the site class on the building damage was evaluated by considering the Mean Damage Ratio parameter (MDR). Achieving fragility curves and MDR curves as a function of spectral acceleration enables a quick and practical risk assessment in existing buildings.

• 융합보안논문지
• /
• 제2권2호
• /
• pp.67-75
• /
• 2002

조직의 정보시스템이 직면한 위험을 분석할 수 있는 위험분석모델을 정보시스템구축 방법론에 적용하여 정보시스템 구축을 진행하면서 위험분석 결과를 반영할 수 있도록 하였다. 위험분석은 조직의 정보자산에 대한 위협과 취약성, 그리고 대응책간의 함수관계를 활용하는 방법으로 조직이 보유한 정보자산에 내재한 취약성의 영향범위와 이에 대응하고 있는 위협의 빈도와 강도 그리고 위협에 대한 대응책의 적용정도를 분석해 종합적인 정보위험수준을 평가하는 방법이다.

• Earthquakes and Structures
• /
• 제6권6호
• /
• pp.611-625
• /
• 2014

This paper presents a simple methodology that integrates an improved storey shear modelling, Incremental Dynamic Analysis and Monte Carlo Simulation in order to carryout vulnerability analysis towards development of fragility curves for Unreinforced Brick Masonry buildings. The methodology is demonstrated by developing fragility curves of a single storey Unreinforced Brick Masonry building for which results of experiment under lateral load is available in the literature. In the study presented, both uncertainties in mechanical properties of masonry and uncertainties in the characteristics of earthquake ground motion are included. The research significance of the methodology proposed is that, it accommodates a new method of damage grade classification which is based on 'structural performance characteristics' instead of 'fixed limiting values'. The usefulness of such definition is discussed as against the existing practice.

• 한국조경학회지
• /
• 제44권4호
• /
• pp.109-120
• /
• 2016

본 연구에서는 열환경 취약성 평가에 관한 국 내외 선행연구 고찰을 바탕으로 열환경 취약성 평가에 적합하면서 도시 및 환경계획 등 공간계획 분야에서 활용할 수 있는 취약성 평가지표를 선정하고, 이를 활용하여 사례지역인 서울시의 열환경 상태를 진단하였다. 이를 위해 폭염, 도시 열섬, 도시 미기후 등 국내 외 열환경 취약성 평가에 활용된 지표들을 고찰하여 도시 열환경 취약성 평가를 위한 15개 지표를 선정하였는데, 기후노출 분야의 건물체적, 민감도 분야의 열환경 취약 건축물, 적응능력 분야의 녹지면적 등 도시구조적 공간적 지표를 포함하였다. 선정된 지표 중 사례지역인 서울지역에 대해 활용가능한 12개 지표의 공간정보를 구축하고, 퍼지이론을 활용한 GIS 공간분석을 통해 서울의 열환경 취약성을 평가하였다. 분석 결과, 강남 지역이 강북 지역보다 열환경에 더 취약한 것으로 파악되었는데, 강남 지역에서는 서초구, 강남구, 동작구, 영등포구, 강서구 일대의 열환경 취약성이 상대적으로 높게 나타났으며, 강북 지역에서는 동대문구, 강북구, 광진구, 중랑구 일대가 다른 구에 비해서 취약성이 높은 것으로 나타났다. 산림지역 및 서울시 외곽지역에 위치한 관악구, 도봉구, 은평구, 노원구 등은 관악산, 북한산 등 산림의 영향으로 인해 '기후노출'과 '민감도' 분야의 취약성이 낮았다. 하지만, 자료수집의 한계로 활용하지 않았던 '적응능력' 분야의 에어컨 보유 현황 지표가 분석에 반영된다면, 서초구, 강남구 등 취약성이 높게 평가된 지역의 결과에 영향을 미쳤을 것으로 예상된다. 본 연구는 기존의 국내 열환경 취약성 평가에서 활용하지 않았던 도시구조적 공간적 지표를 활용함으로써 도시 및 환경계획 분야에서 열취약성을 개선하기 위한 정책 마련에 기여하고, 열환경 위험성을 저감하기 위한 공간계획 수립에 기여할 수 있을 것으로 판단한다.

• 한국지진공학회논문집
• /
• 제17권5호
• /
• pp.237-243
• /
• 2013

In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification factor (TAF), and the inherent and accidental eccentricities. When a structure of less than 6-stories and assigned to seismic design category C or D is designed using equivalent static analysis method, both KBC-2006 and KBC-2009 use the TAF but apply different calculation methods for the of design eccentricity. The design eccentricity in KBC-2006 is calculated by multiplying the sum of inherent eccentricity and accidental eccentricity at each level by a TAF but that in KBC-2009 is calculated by multiplying only the accidental eccentricity by a TAF. In this paper, the damage indices of a building with planar structural irregularity designed by different design eccentricities are compared and the relationship between the earthquake damage and design eccentricity of the building is evaluated. On the basis of this study, the increment of design eccentricity results in the decrement of final eccentricity and global damage index of structure. It is observed that design eccentricity in KBC-2006 reduces the vulnerability of torsional irregular building compared to design eccentricity in KBC-2009.

• Structural Engineering and Mechanics
• /
• 제73권1호
• /
• pp.53-64
• /
• 2020

In different high seismic regions around the world, many non-ductile existing reinforced concrete frame buildings, built without adequate seismic detailing requirements, have been damaged or collapsed after past earthquakes. The assessment and the retrofit of these non-ductile concrete structures is crucial theme of research for all the scientific community of engineers. In particular, a careful assessment of the existing building is fundamental for understanding the failure mechanisms that govern the collapse of the structure or the achievement of the recommended limit states. Based on the seismic assessment, the best retrofit strategy can be designed and applied to the structure. A school building located in Avellino province (Italy) is the case study. The analysis of seismic vulnerability carried out on the mentioned building has highlighted deficiencies in both static and seismic load conditions. The retrofit of the building has been designed based on different retrofit options in order to show the real retrofit design developed from the engineers to achieve the seismic safety of the building. The retrofit costs associated to structural operations are calculated for each case and have been summed up to the costs of the in situ tests. The paper shows a real retrofit design case study in which the best solution is chosen based on the results in terms of structural performance and cost among the different retrofit options.

• Computers and Concrete
• /
• 제26권3호
• /
• pp.203-211
• /
• 2020

Turkey is located in one of the most seismically active regions of in Europe. The majority of the population living in big cities are at high seismic risk due to insufficient structural resistance of the existing buildings. Such a seismic risk brings the need for a comprehensive seismic evaluation based on the risk analysis in Turkey. Determining the seismic resistance level of existing building stock against the earthquakes is the first step to reduce the damages in a possible earthquake. Recently in January 2020, the Elazig earthquake brought the importance of the issue again in the public. However, the excessive amount of building stock, labor, and resource problems made the implementation phase almost impossible and revealed the necessity to carry out alternative studies on this issue. This study aims for a detailed investigation of residential buildings in Antalya, Turkey. The approach proposed here can be considered an improved state of building survey methods previously identified in Turkey's Design Code. Antalya, Turkey's fifth most populous city, with a population over 2.5 Million, was investigated as divided into sub-regions to understand the vulnerability, and a threshold value found for the study area. In this study, 26,610 reinforced concrete buildings between 1 to 7 stories in Antalya were examined by using the rapid visual assessment method. A specific threshold value for the city of Antalya was determined with the second level examination and statistical methods carried out in the determined sub-region. With the micro zonation process, regions below the threshold value are defined as the priority areas that need to be examined in detail. The developed methodology can be easily calibrated for application in other cities and can be used to determine new threshold values for those cities.

• Nuclear Engineering and Technology
• /
• 제53권8호
• /
• pp.2696-2707
• /
• 2021

The purpose of this study is to investigate the efficiency of various structural modeling schemes for evaluating seismic performances and fragility of the reactor containment building (RCB) structure in the advanced power reactor 1400 (APR1400) nuclear power plant (NPP). Four structural modeling schemes, i.e. lumped-mass stick model (LMSM), solid-based finite element model (Solid FEM), multi-layer shell model (MLSM), and beam-truss model (BTM), are developed to simulate the seismic behaviors of the containment structure. A full three-dimensional finite element model (full 3D FEM) is additionally constructed to verify the previous numerical models. A set of input ground motions with response spectra matching to the US NRC 1.60 design spectrum is generated to perform linear and nonlinear time-history analyses. Floor response spectra (FRS) and floor displacements are obtained at the different elevations of the structure since they are critical outputs for evaluating the seismic vulnerability of RCB and secondary components. The results show that the difference in seismic responses between linear and nonlinear analyses gets larger as an earthquake intensity increases. It is observed that the linear analysis underestimates floor displacements while it overestimates floor accelerations. Moreover, a systematic assessment of the capability and efficiency of each structural model is presented thoroughly. MLSM can be an alternative approach to a full 3D FEM, which is complicated in modeling and extremely time-consuming in dynamic analyses. Specifically, BTM is recommended as the optimal model for evaluating the nonlinear seismic performance of NPP structures. Thereafter, linear and nonlinear BTM are employed in a series of time-history analyses to develop fragility curves of RCB for different damage states. It is shown that the linear analysis underestimates the probability of damage of RCB at a given earthquake intensity when compared to the nonlinear analysis. The nonlinear analysis approach is highly suggested for assessing the vulnerability of NPP structures.