• Earthquakes and Structures
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• 제6권5호
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• pp.561-580
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• 2014

After strong earthquakes conventional frames used worldwide in multi - story steel buildings (e.g. moment resisting frames) are not well positioned according to reparability. Two innovative systems for seismic resistant steel frames incorporated with dissipative fuses were developed within the European Research Program "FUSEIS" (Vayas et al. 2013). The first, FUSEIS1, resembles a vertical Vierendeel beam and is composed of two closely spaced strong columns rigidly connected to multiple beams. In the second system, FUSEIS2, a discontinuity is introduced in the composite beams of a moment resisting frame and the dissipative devices are steel plates connecting the two parts. The FUSEIS system is able to dissipate energy by means of inelastic deformations in the fuses and combines ductility and architectural transparency with stiffness. In case of strong earthquakes damage concentrates only in the fuses which behave as self-centering systems able to return the structure to its initial undeformed shape. Repair work after such an event is limited only to replacing the fuses. Experimental and numerical investigations were performed to study the response of the fuses system. Code relevant design rules for the seismic design of frames with dissipative FUSEIS and practical recommendations on the selection of the appropriate fuses as a function of the most important parameters and member verifications have been formulated and are included in a Design Guide. This article presents the design and performance of building frames with FUSEIS 1-1 based on models calibrated on the experimental results.

• Earthquakes and Structures
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• 제14권6호
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• pp.599-614
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• 2018

This study focuses on the earthquake performance of two URM buildings having typical architectural configurations common for residential use constructed per pre-modern code in Albania. Both buildings are unreinforced clay brick masonry structures constructed in 1960 and 1984, respectively. The first building is a three-storey unreinforced one with masonry walls. The second one is confined masonry rising on five floors. Mechanical characteristics of masonry walls were determined based on experimental tests conducted according to ASTM C67-09 regulations. A global numerical model of the buildings was built, and masonry material was simulated as nonlinear. Pushover analyses are carried out to obtain capacity curves. Displacement demands were calculated according to Eurocode 8 and FEMA440 guidelines. Causes of building failures in recent earthquakes were examined using the results of this study. The results of the study showed that the URM building displays higher displacement and shear force demands that can be directly related to damage or collapse. On the other hand, the confined one exhibits relatively higher seismic resistance by indicating moderate damage. Moreover, effects of demand estimation approaches on performance assessment of URM buildings were compared. Deficiencies and possible solutions to improve the capacity of such buildings were discussed.

• 한국전산구조공학회논문집
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• 제28권5호
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• pp.503-510
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• 2015

본 논문에서는 부분 보강된 CFT 기둥의 폭발저항성능을 일반 CFT 기둥과 비교하여 강판 보강의 효과를 확인하였다. 폭발하중을 받는 CFT 기둥의 구조해석에는 폭발과 충돌 해석을 위한 특수한 하이드로코드인 Autodyn을 사용하여 수치해석을 수행하였다. 콘크리트와 이를 둘러싸고 있는 강판 사이의 상호작용을 모델링하는 여러 방법이 있다. 본 연구에서는 기둥의 실제 파괴를 표현하기 위해 마찰 옵션 및 조인 옵션으로 모델링하였다. 해석에 따르면, 부분 보강된 CFT 기둥은 일반 CFT 기둥에 비해 더 나은 폭발저항효과를 나타내었다. 보강 CFT 기둥의 폭발저항성능은 콘크리트를 둘러싸고 있는 부분 보강된 강판의 높이가 높을수록 향상되었으며 CFT 기둥의 단면 크기 이상으로 보강할 것을 추천한다.

• 한국가스학회지
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• 제6권1호
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• pp.32-37
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• 2002

천연가스는 청정 무공해 에너지라는 장점으로 소비량이 매년 크게 증가하고 있는 주요 에너지원이다 천연가스 수요의 증가에 따른 LNG 저장 시설의 확충이 요구되고 있어, 한국가스공사에서는 LNG 저장탱크 설계 기술을 개발하고 있다. 본 논문에서는 유한요소법을 이용하여 LNG 저장탱크의 Roof를 설계에 대하여 연구하였으며, 설계 및 평가에 적용된 하중 조건과 안전 코드는 BS7777 코드에 따라 연구하였다.

• 한국강구조학회 논문집
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• 제15권6호통권67호
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• pp.639-648
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• 2003

연구의 목적은 H형강보에 작용하는 매달림 하중 중 면내 및 면외 모멘트를 그 대상으로 구조설계시 적용되는 설계하중에 대하여 면내 및 면외 모멘트가 스터드 커넥터를 통하여 슬래브를 전달되는 하중전달 경로와 그 성능을 파악하는데 있다. 이를 위하여 면내 및 면외 모멘트를 받는 경우에 대하여 각각 2개의 실험체를 대상으로 가력실험 및 수치해석을 수행하였다. 실험의 변수로는 H형강보의 크기가 적용되었다. 면내 및 면의 모멘트 가력실험결과 현행 강구조계산기준을 따라 설계하면 스터드 커넥터에 의한 H형강보의 모멘트 전달성능을 설계하중을 만족하고 있음을 확인하였다.

• Structural Engineering and Mechanics
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• 제10권4호
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• pp.405-426
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• 2000

Two approximate methods based on mechanism analysis suitable for seismic assessment/design of structural concrete are reviewed. The methods involve use of equal energy concept or equal displacement concept along with appropriate patterns of inelastic deformations to relate structure's maximum lateral displacement to member and plastic deformations. One of these methods (Clough's method), defined here as a ductility-based approach, is examined in detail and a modification for its improvement is suggested. The modification is based on estimation of maximum inelastic displacement using inelastic design response spectra (IDRS) as an alternative to using equal energy concept. The IDRS for demand displacement ductilities are developed for a single degree of freedom model subjected to several accelerograms as functions of response modification factor (R), damping ratios, and strain hardening. The suggested revised methodology involves estimation of R as the ratio of elastic strength demand to code level demand, and determination of design base shear using $R_{design}{\leq}R$ and maximum displacement, determination of plastic displacement using IDRS and subsequent local plastic deformations. The methodology is demonstrated for the case of a 10-story precast wall panel building.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.549-561
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• 2012

Many building foundations are embedded, however it is not easy to compact the backfill around the foundation especially for the deeply embedded ones. The soil condition around the embedded foundation may affect the seismic response of a building due to the weak contact between the soil and the foundation. In this paper, the response accelerations in the short-period range and at the period of 1 second (in the long-period range) for a seismic design spectrum specified in the IBC design code were compared considering perfect and poor backfills to investigate the effect of backfill compaction around the embedded foundation. An in-house finite-element software (P3DASS) which has the capability of horizontal pseudo-3D seismic analysis with linear soil layers was used to perform the seismic analyses of the structure-soil system with an embedded foundation. Seismic analyses were carried out with 7 bedrock earthquake records provided by the Pacific Earthquake Engineering Research Center (PEER), scaling the peak ground accelerations to 0.1 g. The results indicate that the poor backfill is not detrimental to the seismic response of a building, if the foundation is not embedded deeply in the soft soil. However, it is necessary to perform the seismic analysis for the structure-soil system embedded deeply in the soft soil to check the seismic resonance due to the soft soil layer beneath the foundation, and to compact the backfill as well as possible.

• 국제초고층학회논문집
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• 제8권1호
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• pp.57-69
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• 2019

After decades of high-speed development, designing tall buildings as critical components of urban habitat, rather than simply standing aloof from their environments, has become an important concern in many Asian cities. Nevertheless, the lack of quantitative understanding cannot support efficient architectural design or urban renewal that targets better place-making. This study attempts to fill the gap by providing a typological approach for measuring the social impact of tall buildings' ground conditions: that is, public space, podiums, and interfaces. The central business districts (CBD) of three Asian cities, Shanghai, Hong Kong, and Singapore, were selected as cases. Typical patterns and categories of lower-level public spaces among the three CBDs were abstracted via typological analyses and field study. The following evaluation is achieved through the analytic hierarchy process (AHP). This quantified approach helps to provide a visualization of high or low positive social impacts of tall buildings' lower-level public spaces among the three cases. This study also helps to suggest a design code for tall buildings aimed at a more human-oriented urban habitat.

• Earthquakes and Structures
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• 제19권6호
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• pp.471-484
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• 2020

Previous earthquakes show that, structural safety evaluations should include the evaluation of nonstructural components. Failure of nonstructural components can affect the operational capacity of critical facilities, such as hospitals and fire stations, which can cause an increase in number of deaths. Additionally, failure of nonstructural components may result in economic, architectural, and historical losses of community. Accelerations and random vibrations must be under the predefined limitations in structures with high technological equipment, data centers in this case. Failure of server equipment and anchored server racks are investigated in this study. A probabilistic study is completed for a low-rise rigid sample structure. The structure is investigated in two versions, (i) conventional fixed-based structure and (ii) with a base isolation system. Seismic hazard assessment is completed for the selected site. Monte Carlo simulations are generated with selected parameters. Uncertainties in both structural parameters and mechanical properties of isolation system are included in simulations. Anchorage failure and vibration failures are investigated. Different methods to generate fragility curves are used. The site-specific annual hazard curve is used to generate risk curves for two different structures. A risk matrix is proposed for the design of data centers. Results show that base isolation systems reduce the failure probability significantly in higher floors. It was also understood that, base isolation systems are highly sensitive to earthquake characteristics rather than variability in structural and mechanical properties, in terms of accelerations. Another outcome is that code-provided anchorage failure limitations are more vulnerable than the random vibration failure limitations of server equipment.

• 한국지진공학회논문집
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• 제25권1호
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• pp.1-9
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• 2021

Most commercial buildings among existing RC buildings in Korea have a multi-story wall-frame structure where RC shear wall is commonly used as its core at stairways or elevators. The members of the existing middle and low-rise wall-frame buildings are likely arranged in ordinary details considering building occupancy, and the importance and difficulty of member design. This is because there are few limitations, considerations, and financial burdens on the code for designing members with ordinary details. Compared with the intermediate or unique details, the ductility and overstrength are insufficient. Furthermore, the behavior of the member can be shear-dominated. Since shear failure in vertical members can cause a collapse of the entire structure, nonlinear characteristics such as shear strength and stiffness deterioration should be adequately reflected in the analysis model. With this background, an 8-story RC wall-frame building was designed as a building frame system with ordinary shear walls, and the effect of reflecting the shear failure mode of columns and walls on the collapse mechanism was investigated. As a result, the shear failure mode effect on the collapse mechanism was evident in walls, not columns. Consequently, it is recommended that the shear behavior characteristics of walls are explicitly considered in the analysis of wall-frame buildings with ordinary details.