• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.249-256
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• 1999

This study is intended to propose a systematic procedure for the development of the reliability-based seismic safety and cost-effective Performance criteria for design and upgrading of long span PC bridges. In the paper, a set of cost function models for life cycle cost analysis of bridges is proposed. The total life cycle cost functions consist of initial cost and direct/indirect damage costs considering repair/replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses. The damage costs are successfully expressed in terms of Park-Ang median global damage indices and damage probabilities. The proposed approach is successfully applied to model bridges in both regions of a moderate seismicity area like Seoul, Korea and a high one like Tokyo, Japan. It may be expected that the proposed approach can be effectively utilized for the development of cost-effective performance criteria for design and upgrading of various types of bridges as well as long span PC bridges.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.255-262
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• 2003

In present Korea Highway Bridge Standards the lap splice of longitudinal bars in a potential plastic hinge region is allowed so that large amount of transverse rebar specified in high seismicity regions Is required to prevent brittle bond failure If the brittle failure effects can be completely removed from the conventional designed piers, the amount of transverse rebar will be reduced drastically. In this study scaled models with solid and hollow rectangular sections were tested to investigate the seismic behavior of RC piers with 50％ of lap-spliced longitudinal bars in plastic hinge regions. In the tests the typical flexural failure conducting a ductile behavior were observed in both models. It is shown that the 50％ of lap-spliced bars can be considered as a good alternative of seismic detailing for longitudinal bars.

• Earthquakes and Structures
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• 제22권4호
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• pp.373-386
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• 2022

The development of performance-based design methodologies requires a reasonable definition of a displacement-response spectrum. Although ground motions are known to be significantly affected by the resonant-like amplification behavior caused by multiple wave reflections within the surface soil, such a soil-resonance effect is seldom explicitly considered in current-displacement spectral models. In this study, an analytical approach is developed for the construction of displacement-response spectra by considering the soil-resonance effect. For this purpose, a simple and rational equation is proposed for the response spectral ratio at the site fundamental period (SRTg) to represent the soil-resonance effect based on wave multiple reflection theory. In addition, a bilinear model is adopted to construct the soil displacement-response spectra. The proposed model is verified by comparing its results with those obtained from actual observations and SHAKE analyses. The results show that the proposed model can lead to very good estimations of SRTg for harmonic incident seismic waves and lead to reasonable estimations of SRTg and soil displacement-response spectra for earthquakes with a relatively large magnitude, which are generally considered for seismic design, particularly in high-seismicity regions.

• 자원환경지질
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• 제55권6호
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• pp.633-648
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• 2022

경기도 연천 지역에서 집중적으로 발생한 군발지진의 원인을 파악하기 위해서 중력 자료를 분석하였다. 그 결과 연천 지역에는 북서-남동 방향의 안행상(En echelon) 구조가 발달하는 것으로 나타났다. 또한, 동두천 단층 동쪽 지역은 꽃다발구조(flower structure)를 수반한 수직 지구조 운동으로 인해서 고밀도의 기반암 물질들이 부분적으로 지표 가까이 상승한 것으로 해석되었다. 동두천 단층의 파쇄대 폭은 약 200 m, 깊이는 최소 5 km이며, 밀도는 인접 지층보다 평균 약 15% 낮은 것으로 평가된다. 지하 5 km 이내에서 발생한 천발지진은 지표 가까이 관입한 고밀도 암석에 발달된 저밀도의 안행상 단층 파쇄대를 따라 집중되어 발생한 것으로 분석되는데, 이는 동두천 단층의 우수향 운동 때문에 남북 방향으로 작용한 응력이 안행상 단층을 활성화한 결과로 해석된다.

• Structural Engineering and Mechanics
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• 제33권2호
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• pp.137-158
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• 2009

This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.

• 한국지진공학회논문집
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• 제20권6호
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• pp.351-360
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• 2016

In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length($40d_b$ and $50d_b$) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.

• 한국전산구조공학회논문집
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• 제25권6호
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• pp.513-523
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• 2012

본 연구는 횡력저항시스템별로 프로토타입 모델을 선정하고 지진지역과 비정형성에 따른 내진성능 영향력을 검토하였다. 프로토타입 모델은 다이아그리드 시스템과 브레이스튜브 시스템 그리고 아웃리거 시스템을 선정하였다. 또한 각 횡력저항시스템별 평면 비틀림 각도를 $0^{\circ}$, $1^{\circ}$($1.5^{\circ}$), $2^{\circ}$($3^{\circ}$) 씩 변화하여 내진성능을 검토하였다. 지진지역은 강진지역(LA), 약진지역(Boston)을 선정하였다. 선형응답해석은 프로토타입 모델의 풍변위, 고유주기를 검토하였다. Non-Linear Response History(NLRH) 해석에서는 밑면전단력, 층간변위비를 검토하였다. 검토결과 다이아그리드 시스템과 브레이스튜브 시스템 그리고 아웃리거 시스템 모두 평면 비틀림 각도가 증가할수록 건물 전체의 강성이 줄어들었다. 또한 평면 비틀림 각도가 증가할수록 풍변위와 고유주기 결과가 증가하고 건물 전체의 강성이 줄어들어 밑면전단력이 감소하였다. 끝으로, NLRH 해석 결과 강진과 약진지역 모두 Tall Building Initiative(TBI)의 Maximum Considered Earthquake(MCE)수준의 층간변위비 제한값 0.045를 만족하여 허용범위내의 내진성능을 만족하고 있는 것으로 나타났다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제18권3호
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• pp.51-59
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• 2012

Over a past century, the continuity in post-earthquake serviceability of medical facilities has been demonstrated to be essential for sustaining a society and/or a nation stable. However, not many countries including Korea have paid appropriate attention to such a lesson learned from the previous experiences of the countries located in high seismicity for various reasons, one of which may be the lack of social consensus in allocating a portion of the resources to the earthquake preparedness. As a result, an earthquake-related policy might have been pushed away out of the list of priority in the government agenda. Therefore, the present paper attempts to persuade the public general, experts and government officials together to seek a way to upgrade the seismic safety of the country a step forward by enhancing the seismic performance of medical facilities. For this the framework of seismic design codes and standards for medical facilities, and Californian experience in managing the seismic performance enhancement program and U.S.-Italian collaborative study to improve the seismic safety of Italian hospitals are reviewed. Finally, a list of further researches and practices to perform for seismic enhancement of medical facilities in Korea are suggested.

• Steel and Composite Structures
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• 제15권3호
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• pp.281-298
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• 2013

Composite special moment frame is one of the systems that are utilized in areas with low to high seismicity to deal with earthquake forces. Composite moment frames are composed of reinforced concrete columns (RC) and steel beams (S); therefore, the connection region is a combination of steel and concrete materials. In current study, a three dimensional finite element model of composite connections is developed. These connections are used in special composite moment frame, between reinforced concrete columns and steel beams (RCS). Finite element model is discussed as a most reliable and low cost method versus experimental procedures. Based on a tested connection model by Cheng and Chen (2005), the finite element model has been developed under cyclic loading and is verified with experimental results. A good agreement between finite element model and experimental results was observed. The connection configuration contains Face Bearing Plates (FBPs), Steel Band Plates (SBPs) enveloping around the RC column just above and below the steel beam. Longitudinal column bars pass through the connection with square ties around them. The finite element model represented a stable response up to the first cycles equal to 4.0% drift, with moderately pinched hysteresis loops and then showed a significant buckling in upper flange of beam, as the in test model.

• Structural Engineering and Mechanics
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• 제75권3호
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• pp.295-309
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• 2020

The construction of Reinforced Concrete (R/C) buildings with unreinforced masonry infills is part of the traditional building practice in many countries with regions of high seismicity throughout the world. When these buildings are subjected to seismic motions the presence of masonry infills and especially their configuration can highly influence the seismic damage state. The capability to avoid configurations of masonry infills prone to seismic damage at the stage of initial architectural concept would be significantly definitive in the context of Performance-Based Earthquake Engineering. Along these lines, the present paper investigates the potential of instant prediction of the damage response of R/C buildings with various configurations of masonry infills utilizing Artificial Neural Networks (ANNs). To this end, Multilayer Feedforward Perceptron networks are utilized and the problem is formulated as pattern recognition problem. The ANNs' training data-set is created by means of Nonlinear Time History Analyses of 5 R/C buildings with a large number of different masonry infills' distributions, which are subjected to 65 earthquakes. The structural damage is expressed in terms of the Maximum Interstorey Drift Ratio. The most significant conclusion which is extracted is that the ANNs can reliably estimate the influence of masonry infills' configurations on the seismic damage level of R/C buildings incorporating their optimum design.