• Earthquakes and Structures
• /
• 제5권4호
• /
• pp.379-394
• /
• 2013

Post-earthquake fire (PEF) can lead to a rapid collapse of buildings damaged partially as a result of prior earthquake. Almost all standards and codes for the design of structures against earthquake ignore the risk of PEF, and thus buildings designed using those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the Immediate Occupancy, Life Safety and Collapse Prevention performance levels of structures, designed to the ACI 318-08 code, after they are subjected to an earthquake level with PGA of 0.35g. This investigation is followed by a fire analysis of the damaged structures, examining the time taken for the damaged structures to collapse. As a point of reference, a fire analysis is also performed for undamaged structures and before the occurrence of earthquake. The results indicate that the vulnerability of structures increases dramatically when a previously damaged structure is exposed to PEF. The results also show that the damaging effects of post-earthquake fire are exacerbated when initiated from the second and third floor. Whilst the investigation is made for a certain class of structures (conventional buildings, intermediate reinforced structure, 3 stories), the results confirm the need for the incorporation of post-earthquake fire into the process of analysis and design, and provides some quantitative measures on the level of associated effects.

• 한국지진공학회논문집
• /
• 제20권3호
• /
• pp.171-180
• /
• 2016

Earthquake event keeps increasing every year, and the recent cases of earthquake hazards invoke the necessity of seismic study in Korea, as geotechnical earthquake hazards, such as strong ground motion, liquefaction and landslides, are a significant threat to structures in industrial hub areas including coastal facilities. In this study, systemized framework of integrated assessment of earthquake-induced geotechnical hazard was established using advanced geospatial database. And a visible simulation of the framework was specifically conducted at two coastal facility areas in Incheon. First, the geospatial-grid information in the 3D domain were constructed with geostatistical interpolation method composed of multiple geospatial coverage mapping and 3D integration of geo-layer construction considering spatial outliers and geotechnical uncertainty. Second, the behavior of site-specific seismic responses were assessed by incorporating the depth to bedrock, mean shear wave velocity of the upper 30 m, and characteristic site period based on the geospatial-grid. Third, the normalized correlations between rock-outcrop accelerations and the maximum accelerations of each grid were determined considering the site-specific seismic response characteristics. Fourth, the potential damage due to liquefaction was estimated by combining the geospatial-grid and accelerations correlation grid based on the simplified liquefaction potential index evaluation method.

• Advances in concrete construction
• /
• 제10권4호
• /
• pp.333-343
• /
• 2020

In the architectural design process, the selection and configuration of the structural system significantly affect the earthquake behaviours of the reinforced concrete buildings. The main purpose of this study, the effects on the earthquake performances and the rough construction cost of the buildings of the slab type in reinforced concrete buildings are to examine comparatively for different local soil classes. The results obtained from this study have been determined that the building model having slabs with beams is safer compared to other types of slabs, especially when considering the vertical bearing structural elements (columns). It also shows that other types of slab, except for slab with beams, reduce the earthquake performances of reinforced concrete buildings, increase the displacement values, 1st natural vibration period values and the cost of rough construction. This matter reveals that slab type is quite important and the preference of beamed slabs in reinforced concrete buildings to be constructed in earthquake zones would be more appropriate in terms of safety and cost.

• 한국재난정보학회 논문집
• /
• 제13권1호
• /
• pp.89-95
• /
• 2017

대형재해 발생 전 동물 이상행동 목격사례가 심심치 않게 보도되고 있다. 동물 이상행동이 대형재해 발생과 연관이 있을까, 그렇다면 재해발생을 예지할 수 있을까? 본 연구의 목적은 동물 이상행동과 지진전조 관련 선행연구 고찰을 통해 이에 대한 해답을 탐구(探求)해 봄에 있다. 본 연구에서는 분석방법론에 따라 사례조사, 실험분석, 관찰 분석을 통한 가설검증 연구와 그 한계점을 고찰하였다. 선행연구는 결과적으로 '동물 이상행동을 전조현상으로 볼 수도 있다'와 '보기 어렵다'로 이분되며, 양쪽 모두 다수의 연구가 수행되었다. 그러나 관련연구에서는 데이터의 신뢰성 검증이 어렵고, 우연하게 계측된 데이터의 적은 샘플 수, 적합한 데이터 확보의 어려움 등 공통된 한계점을 지적하고 있다. 이에 지진예지에의 활용 가능성 검토단계에 이르기 위해서는 동물 이상행동과 지진발생과의 인과관계에 대한 과학적 검증이 선행되어야 한다.

• 한국항해항만학회지
• /
• 제47권1호
• /
• pp.18-24
• /
• 2023

동일본 대지진 이후부터 성인 피해자들의 증언을 정리한 보도와 서적 등이 간행되어 당시의 피난 상황을 알려지게 되었다. 그러나 이러한 자료 중 학생들의 피난 상황 정보는 매우 적으며 지진이나 해일에 의해 이들이 어떤 행동을 취하고 피난을 했는지에 대해서는 충분히 밝혀지지 않았다. 본 연구에서는 동일본 대지진에서 학생들의 피난 행동을 분석 및 고찰하여 향후 예상되는 재난에 대한 학생들의 피난행동에 관한 지식을 얻는 것을 목적으로 한다. 연구결과 학생들은 지진해일에 대한 정보를 수동적으로 얻고 있으며, 피난행동은 성인에 크게 의존하고 있었다. 지진 발생 직후 행동은 흔들림이 멈출 때까지 자신의 몸을 보호하며 가만히 있는 경우가 많았고 흔들림이 잦아든 후 다른 장소로 이동하는 취하는 경향을 알 수 있었다. 지진해일의 위협으로부터 벗어나기 위해 리아스식 해안지역 학생들은 주로 높은 곳으로 이동하였고, 평야지역 학생들은 학교 등 높은 건물로 이동하여 수직 이동하는 것을 알 수 있었다. 피난 장소로의 이동 형태는 한번의 이동으로 최종 피난장소에 도착하였으며 이는 사전에 피난 장소를 결정하고 움직였다고 판단된다.

• Advances in concrete construction
• /
• 제1권1호
• /
• pp.29-44
• /
• 2013

Post earthquake fire (PEF) can lead to the collapse of buildings that are partially damaged in a prior ground-motion that occurred immediately before the fire. The majority of standards and codes for the design of structures against earthquake ignore the possibility of PEF and thus buildings designed with those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the Life-Safety performance level of structures designed to the ACI 318-08 code after they are subjected to two different earthquake levels with PGA of 0.35 g and 0.25 g. This is followed by a four-hour fire analysis of the weakened structure, from which the time it takes for the weakened structure to collapse is calculated. As a benchmark, the fire analysis is also performed for undamaged structure and before occurrence of earthquake. The results show that the vulnerability of structures increases dramatically when a previously damaged structure is exposed to PEF. The results also show the damaging effects of post earthquake fire are exacerbated when initiated from second and third floor. Whilst the investigation is for a certain class of structures (regular building, intermediate reinforced structure, 3 stories), the results confirm the need for the incorporation of post earthquake fire in the process of analysis and design and provides some quantitative measures on the level of associated effects.

• Earthquakes and Structures
• /
• 제7권6호
• /
• pp.1001-1024
• /
• 2014

The size of spread footings was found to be unnecessarily large from some actual engineering practices constructed in Taiwan, due to the strict design provisions related to footing uplift. According to the earlier design code in Taiwan, the footing uplift involving separation of footing from subsoil was permitted to be only up to one-half of the foundation base area, as the applied moment reaches the value of plastic moment capacity of the column. The reason for this provision was that rocking of spread footings was not a favorable mechanism. However, recent research has indicated that rocking itself may not be detrimental to seismic performance and, in fact, may act as a form of seismic isolation mechanism. In order to clarify the effects of the relative strength between column and foundation on the rocking behavior of a column, six circular reinforced concrete (RC) columns were designed and constructed and a series of rocking experiments were performed. During the tests, columns rested on a rubber pad to allow rocking to take place. Experimental variables included the dimensions of the footings, the strength and ductility capacity of the columns and the intensity of the applied earthquake. Experimental data for the six circular RC columns subjected to quasi-static and pseudo-dynamic loading are presented. Results of each cyclic loading test are compared against the benchmark test with fixed-base conditions. By comparing the experimental responses of the specimens with different design details, a key parameter of rocking behavior related to footing size and column strength is identified. For a properly designed column with the parameter higher than 1, the beneficial effects of rocking in reducing ductility and the strength demand of columns is verified.

• 한국지진공학회논문집
• /
• 제6권3호
• /
• pp.53-62
• /
• 2002

지반조건은 구조물의 지진거동에 매우 큰 영향을 미치고 성능에 기준한 내진설계에 중요한 요소이다. 이 논문에서는 지진에 의한 지반의 비선형성을 포함한 지반의 비선형성이 구조물의 탄성지진거동에 미치는 영향을 지반 구조물 일괄해석 유한요소법과 지반의 비선형성을 구현하기 위해 Ramberg-Osgood 토질모델에 대한 근사선형 반복해석법으로 연구하였다. 연구는 말뚝기초의 유무를 고려한 주기가 변하는 선형 단자유도계에 지표에서 기록된 1940년 EI Centre지진을 적용하여 수행하였다. 연구결과에 의하면 연약지반의 비선형 특성 영향이 구조물의 탄성 지진거동에 매우 중요하곡 성능에 기준한 지반의 비선형성을 고려한 구조물의 내진설계가 필요하다는 것을 잘 보여주고 있다.

• 한국방재학회 논문집
• /
• 제11권1호
• /
• pp.59-66
• /
• 2011

지진재해로 인한 라이프라인의 피해는 구조물의 손상뿐만 아니라, 통신장애, 전력 가스 수자원 등 다양한 생활에너지의 공급에 장애를 발생시킨다. 이러한 지진재해에 효율적으로 대응하기 위해 미국과 일본에서는 HAZUS 및 HERAS와 같은 지진재해평가 시스템을 구축하여 활용하고 있다. 국내에서도 이러한 시스템 구축을 위해 노력하고 있으나, 근본적으로 구조물의 지진 해석을 통한 평가자료가 부족한 실정이다. 이에 본 연구에서는 다양한 구조물 중 국내에 시공된 수많은 매설관을 조사하여 관 재질 특성에 따라 연성관과 취성관으로 분류하고 이에 대한 동적 거동을 분석하였다. 다양한 지진하중 하에서 국내 및 미국의 시공기준에 따라 매설관의 동적 거동을 비교 평가하였다. 본 연구를 통하여 미국 HAZUS 프로그램의 알고리즘에 따른 국내의 매설관 손상평가의 적정성을 조사하였다.

• 한국지진공학회논문집
• /
• 제25권6호
• /
• pp.261-266
• /
• 2021

Nuclear power plants in Korea were designed and evaluated based on the NRC's Regulatory Guide 1.60, a design response spectrum for nuclear power plants. However, it can be seen that the seismic motion characteristics are different when analyzing the Gyeongju earthquake and the Pohang earthquake that has recently occurred in Korea. Compared to the design response spectrum, seismic motion characteristics in Korea have a larger spectral acceleration in the high-frequency region. Therefore, in the case of equipment with a high natural frequency installed in a nuclear power plant, seismic performance may be reduced by reflecting the characteristics of domestic seismic motions. The failure modes of the equipment are typically structural failure and functional failure, with an anchorage failure being a representative type of structural failure. In this study, comparative analyses were performed to decide whether to consider the inelastic behavior of the anchorage or not. As a result, it was confirmed that the seismic performance of the anchorages could be increased by considering the inelastic behavior of an anchorage.