• Earthquakes and Structures
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• 제24권1호
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• pp.11-20
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• 2023

"Performance-based design (PBD)" is based on designing a structure with choosing a performance target under design criteria to increase the structure's resistance against earthquake effect. The plastic hinge formation is determined as one of the fundamental data in finite elements nonlinear analysis to distinguish the condition of the structure where more significant potential damage could occur. If the number of plastic hinges in the structure is increased, the total horizontal load capability of the structure is increased, also. Theoretically, when the number of plastic hinges of the plane frame structure reaches "the degree of hyperstaticity plus one", the structure will reach the capability of the largest ultimate horizontal load. As the number of plastic hinges to be formed in the structure increases towards the theoretical plastic hinge number (TPHN), the total horizontal load capability of the structure increases, proportionally. In the previous studies of the authors, the features of examining the new performance criteria were revealed and it was formulated as follows "Increase the total number of plastic hinges to be formed in the structure to the number of theoretical plastic hinges as much as possible and keep the structure below its targeted performance with related codes". With this new performance criterion, it has been shown that the total lateral load capability of the building is higher than the total lateral load capability obtained with the traditional PBD method by the FEMA 440 and FEMA 356 design guides. In this study, PBD analysis results of structures with frame carrier systems are presented in the light of the Turkey Building Earthquake Code 2019. As a result of this study, it has been shown that the load capability of the structure in the examples of structures with frame carrier system increases by using this new performance criterion presented, compared to the results of the examination with the traditional PBD method in TBEC 2019.

• Earthquakes and Structures
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• 제12권6호
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• pp.699-712
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• 2017

This study evaluates the effectiveness of a newly developed retrofitting scheme for masonry-infilled non-ductile RC frames experimentally and by numerical simulation. The technique focuses on modifying the load path and yield mechanism of the infilled frame to enhance the ductility. A vertical gap between the column and the infill panel was strategically introduced so that no shear force is directly transferred to the column. Steel brackets and small vertical steel members were then provided to transfer the interactive forces between the RC frame and the masonry panel. Wire meshes and high-strength mortar were provided in areas with high stress concentration and in the panel to further reduce damage. Cyclic load tests on a large-scale specimen of a single-bay, single-story, masonry-infilled RC frame were carried out. Based on those tests, the retrofitting scheme provided significant improvement, especially in terms of ductility enhancement. All retrofitted specimens clearly exhibited much better performances than those stipulated in building standards for masonry-infilled structures. A macro-scale computer model based on a diagonal-strut concept was also developed for predicting the global behavior of the retrofitted masonry-infilled frames. This proposed model was effectively used to evaluate the global responses of the test specimens with acceptable accuracy, especially in terms of strength, stiffness and damage condition.

• Structural Engineering and Mechanics
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• 제59권4호
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• pp.653-669
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• 2016

Recent earthquakes worldwide show that a significant portion of the earthquake shaking happens in the vertical direction. This phenomenon has raised significant interests to consider the vertical ground motion during the seismic design and assessment of the structures. Strong vertical ground motions can alter the axial forces in the columns, which might affect the shear capacity of reinforced concrete (RC) members. This is particularly important for non-ductile RC frames, which are very vulnerable to earthquake-induced collapse. This paper presents the detailed nonlinear dynamic analysis to quantify the collapse risk of non-ductile RC frame structures with varying heights. An array of non-ductile RC frame architype buildings located in Los Angeles, California were designed according to the 1967 uniform building code. The seismic responses of the architype buildings subjected to concurrent horizontal and vertical ground motions were analyzed. A comprehensive array of ground motions was selected from the PEER NGA-WEST2 and Iran Strong Motions Network database. Detailed nonlinear dynamic analyses were performed to quantify the collapse fragility curves and collapse margin ratios (CMRs) of the architype buildings. The results show that the vertical ground motions have significant impact on both the local and global responses of non-ductile RC moment frames. Hence, it is crucial to include the combined vertical and horizontal shaking during the seismic design and assessment of non-ductile RC moment frames.

• Nuclear Engineering and Technology
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• 제37권2호
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• pp.191-200
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• 2005

Shaking table tests of the seismic behavior of a steel frame structure model were performed. The purpose of these tests was to estimate the effects of a near-fault ground motion and a scenario earthquake based on a probabilistic seismic hazard analysis for nuclear power plant structures. Three representative kinds of earthquake ground motions were used for the input motions: the design earthquake ground motion for the Korean nuclear power plants, the scenario earthquakes for Korean nuclear power plant sites, and the near-fault earthquake record from the Chi-Chi earthquake. The probability-based scenario earthquakes were developed for the Korean nuclear power plant sites using the PSHA data. A 4-story steel frame structure was fabricated to perform the tests. Test results showed that the high frequency ground motions of the scenario earthquake did not damage the structure at the nuclear power plant site; however, the ground motions had a serious effect on the equipment installed on the high floors of the building. This shows that the design earthquake is not conservative enough to demonstrate the actual danger to safety related nuclear power plant equipment.

• 콘크리트학회지
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• 제3권3호
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• pp.111-119
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• 1991

작금에 사용되고 있는 RC 구조물의 대개의 내진설계기법은 지진시 RC 구조물에 발생되는 손상의 분포상태를 고려치 않고 있다. 본 논문은 철근 콘크리트 구조물의 새로운 내진설계법 즉 Miner's 법칙을 수정한 지진 발생시의 흡수에너지(Dissipated Energy)를 변수로 하는 손상모델(3)를 사용하여 RC 프레임의 각각의 Node에서의 손상정도를 수치적으로 나타내고 이들 손상값의 크기가 전 부재에 고르게 분포토록 하기 위하여 각 부재의 주철근량을 설계변수로 채택한 설계기법을 소개하였다. 사용된 이력모델 및 손상모델의 정확성을 평가하기 위하여 해석적인 하중-변형곡선을 재생하여 실험곡선과 비교분석하였으며 제안된 내진설계법의 유용성은 3-bay 4-story 프레임 모델을 사용하여 입증하였다.

• 한국지진공학회논문집
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• 제11권2호
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• pp.39-45
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• 2007

본 연구에서는 확률과 신뢰성을 바탕으로 개발된 FEMA-355F의 내진성능 평가기법을 적용하여 철근 콘크리트 모멘트골조 건물의 내진성능을 평가하였다. 철골 구조물을 대상으로 개발된 FEMA의 성능평가 방식을 다른 구조 시스템에 적용할 때 각 시스템에 적합한 성능값을 결정해야하며, 요구값과 성능값 계산 시 수반되는 불확실성을 반영하는 계수들을 새로이 구해야 한다. 이를 수행하기 위해 예제 건물을 IBC 2003에 따라 설계한 후, 성능평가에 필요한 변수들을 결정하기 위해 건물의 위치에 적합한 지반운동을 이용하여 비탄성 동적 해석을 수행하였다. 해석결과에 따르면 계산된 성능값의 분포는 요구값에 비해 상대적으로 작았으며, 이 결과는 본 연구에서 결정된 성능값이 합리적임을 나타낸다. 구해진 신뢰도는 부분 및 전체 붕괴 모두에 대해 목표치를 초과하였으므로 예제 건물은 목표 성능을 만족하는 것으로 나타났다.

• 화약ㆍ발파
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• 제40권4호
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• pp.35-46
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• 2022

오래된 산업단지를 해체하고 해체한 산업부지를 원래의 자연환경으로 복원하는 공사가 진행 중인 가운데, 본 논문에서는 노후화된 산업단지 내의 대형 철골구조물 중 하나인 터빈동을 발파해체공법 중 점진붕괴공법을 적용하여 해체한 사례를 소개한다. 터빈동을 절단 해체하기 위해 금속 제트가 발생하는 장약용기를 사용하였다. 발파구간 중 절단 두께가 두꺼운 부분은 가스와 산소 불꽃 또는 아크열에 의해 깊은 홈을 파는 방법인 가우징을 적용하여 절단 두께를 30mm 이하로 조절하였다. 터빈동 발파해체에 사용한 총 장약량은 175kg, 전자뇌관 165발, 장약용기 124개이다. 발파해체 결과, 터빈동은 예측한 방향으로 붕괴하였으며, 주변 시설물에 피해 없이 발파해체를 완료하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.164-165
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• 2015

Modular construction technique is an adaptation of factory-based mass production concept in ordinary manufacturing industries to construction industry and it assumes that panels, units, etc. are fabricated in factories and assembled in construction sites. Given its structural limitations, modular construction technique is primarily used in low-story buildings whose maximum height is usually five stories, but researchers are actively studying possible adaptation of modular construction technique to high-rise building designs these days as in the case of infill-type modular construction design. Infill-type modular construction technique, most frequently used in high-rise building construction projects, completes frame construction first in reinforced concrete structures and fills unit modules in such structures. However, infill-type modular construction technique leads to longer construction schedule accompanying increase in construction cost, cost overrun due to additional of temporary work, and possible damage to units in the wake of facility construction. Accordingly, this study is performed as a basic study for the development of bottom-up infill-type modular construction technique intended to construct structural frames and fill in units sequentially in a bid to address such drawbacks of current infill-type modular construction technique.

• Earthquakes and Structures
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• 제26권3호
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• pp.175-189
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• 2024

Aiming at studying the plastic hinge (PH) evolution regularities and failure mode of rocking wall moment frame (RWMF) structure in earthquakes, the whole-working history analysis of seismic performance state of RWMF structure based on co-operation performance and PH evolution was carried out. Building upon the theoretical analysis of the elastic internal forces and deformations of RWMF structures, nonlinear finite element analysis (FEA) methods were employed to perform both Pushover analysis and seismic response time history analysis under different seismic coefficients (δ). The relationships among PH occurrence ratios (R_ph), inter-story drifts and δ were established. Based on the plotted curve of the seismic performance states, evaluation limits for the R_ph and inter-story drifts were provided for different performance states of RWMF structures. The results indicate that the R_ph of RWMF structures exhibits a nonlinear evolution trend of "fast at first, then slow" with the increasing of δ. The general pattern is characterized by the initial development of beam hinges in the middle stories, followed by the development towards the top and bottom stories until the beam hinges are fully formed. Subsequently, the development of column hinges shifts from the bottom and top stories towards the middle stories of the structure, ultimately leading to the loss of seismic lateral capacity with a failure mode of partial beam yield, demonstrating a global yielding pattern. Moreover, the limits for the R_ph and inter-story drifts effectively evaluate the five different performance states of RWMF structures.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.129-136
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• 1999

This research proposes an effective analytical methodology for vertical vibration of three dimensional frame structures including slabs. The consideration of slabs, although allows more precise results, requires large amount of computer time and memory space due to the use of plane stress elements. In consideration of these problems, a method to properly manage nodal points and degrees of freedom is proposed based on matrix condensation technique. Also studied is the use of substructure method to obtain fast and reliable results with simple input data when they are applied to conventional building structures.