• 한국구조물진단유지관리공학회 논문집
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• 제23권1호
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• pp.36-44
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• 2019

본 연구의 목적은 강 - PC 복합모듈 골조를 구성하는 프레스 성형된 비대칭 기둥과 보 접합부의 구조적 성능을 평가하는 것이다. 모듈러 골조를 구성하는 대부분의 접합부는 폐쇄형의 사각형 강재 기둥 단면을 주로 사용한다. 폐쇄형의 기둥 단면을 사용한 기둥-보 접합부는 시공성을 감소시키고 내화성을 확보하는데 어려움이 있다. 이러한 단점을 극복하기 위하여 강판을 프레스로 성형하여 비대칭 개방형 단면 내에 콘크리트를 충진하는 것이다. 프레스 성형된 비대칭 기둥-보 접합부의 구조적 성능을 조사하기 위해 총 4개의 실험체를 제작하였다. 실험결과, 비대칭 기둥의 구조적 성능과 거동이 비대칭 기둥 단면이 합성되는지 또는 기둥의 폭-두께 비율에 따라 달라지는지를 보여주었다. 프레스 성형된 비대칭 기둥-보 접합부의 구조적 성능은 실험결과와 이론식을 비교하여 평가하였다.

• 미생물과산업
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• 제20권1호
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• pp.23-27
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• 1994

본고에서는 화학적수법으로 다양한 특이한 기질을 제조하여 여기에 입체특이적 성질(stereospecificity)과 입체선택적 성질(steroselectivity)이 높은 생물학적 방법들 중에서 주로 lipase를 이용한 부제가수분해반응(asymmetric hydrolysis)과 그 역반응인 에스테르화반응(esterification)등을 도입한 chiral building block의 제조와 이를 이용한 곤충 생리활성물질인 pheromone의 합성에 대한 최근의 많은 예들중 상품화를 시도하고 있는 매미나방의 pheromne인 (+)-disparlure에 대하여 간단히 소개하고자 한다.

• Earthquakes and Structures
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• 제7권4호
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• pp.587-607
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• 2014

Progressive collapse, which is referred to as the collapse of the entire building under local damages, is a common failure mode happened by earthquakes. The collapse process highly depends on the whole structural system. Since, asymmetry of the building plan leads to the local damage concentration; it may intensify the progressive collapse mechanism of asymmetric buildings. In this research the progressive collapse of regular and irregular 6-story RC ordinary moment resisting frame buildings are studied in the presence of the earthquake loads. Collapse process and collapse propagation are investigated using nonlinear time history analyses (NLTHA) in buildings with 5%, 15% and 25% mass asymmetry with respect to the number of collapsed hinges and story drifts criteria. Results show that increasing the value of mass eccentricity makes the asymmetric buildings become unstable earlier and in the early stages with lower number of the collapsed hinges. So, with increasing the mass eccentricity in building, instability and collapse of the entire building occurs earlier, with lower potential of the progressive collapse. It is also demonstrated that with increasing the mass asymmetry the decreasing trend of the number of collapsed beam and column hinges is approximately similar to the decreasing trend in the average story drifts of the mass centers and stiff edges. So, as an alternative to a much difficult-to-calculate local response parameter of the number of collapsed hinges, the story drift, as a global response parameter, measures the potential of progressive collapse more easily.

• 지질공학
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• 제28권3호
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• pp.397-409
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• 2018

일본 시코쿠 서부의 이즈미 퇴적분지는 중앙구조선의 굴곡부(사쿠라기 굴곡) 서쪽에 널리 분포하고 있다. 시코쿠 서부의 이즈미 퇴적분지의 형성 메커니즘은 아직 잘 알려지지 않고 있다. 이즈미 퇴적분지의 층서는 일반적으로 굴곡부를 향해서 퇴적시기가 젊게 퇴적되는 경향을 보인다. 이 특징은 비대칭 pull-apart 퇴적분지와 비슷하다. 그래서, 이즈미 퇴적분지가 비대칭 pull-apart 퇴적분지인지에 대한 연구를 아날로그 모델실험을 이용하여 수행하였다. 실험을 실시하여 길이 60 cm, 폭 20 cm 정도의 퇴적 분지가 형성되었다. 모래 표면에는 퇴적분지를 감싸듯 2차 단층으로 정단층이 나타났다. 또한, 변위방향과 평행한 단면에서는 퇴적한 층이 개방성의 굴곡부를 향해서 층리가 젊어져 가는 구조가 보였다. 변위방향과 수직단면에서는 주로 단층과 반대의 경사를 가진 선상(listric) 정단층이 확인되었다. 이 결과는 이즈미 시코쿠 서부의 퇴적분지와 매우 유사하며, 이즈미 시코쿠 서부의 퇴적분지가 비대칭 pull-apart퇴적분지의 가능성을 지지하는 것이다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.314-321
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• 2000

Excessive torsional behavior of asymmetric building structures is observed to be the main cause of the poor seismic performance. Concepts of current design provisions for torsion are based on the assumption that the strength of the lateral load resisting elements can be adjusted without changing their stiffness. This paper investigates inelastic torsional effects of multi-story high rise residential building in Korea on increase of strength demand and ductility of members using some methods published in literature. The methods analyze the reduction of strength and member ductility resulting from torsional mechanisms. This study shows that use of these concepts control inelastic torsion during preliminary seismic design of multi-story building of irregular plans.

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

• Earthquakes and Structures
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• 제12권5호
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• pp.543-557
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• 2017

Results of an extensive study aiming to properly extend the well known pushover analysis into 3-D problems of asymmetric buildings are presented in this paper. The proposed procedure uses simple, 3 DOF, one-story models with shear-beam type elements in order to quantify the effects of inelastic torsional response of such buildings. Correction coefficients for the response quantities at the "stiff" and "flexible" sides are calculated using results from non-linear time history analyses of the simple models. Their values are then applied to the results of a simple, plane pushover analysis of the detailed building models. Results from the application of the new method for a set of three, conventionally designed, five-story buildings with high values of uniaxial eccentricities are compared with those obtained from multiple non-linear dynamic time history analyses, as well as from similar pushover methods addressing the same problem. This initial evaluation indicates that the proposed procedure is a clear improvement over the simple (conventional) pushover method and, in most cases, more accurate and reliable than the other methods considered. The accuracy, however, of all these methods is reduced substantially when they are applied to torsionally flexible buildings. Thus, for such challenging problems, use of inelastic dynamic analyses for a set of two component earthquake motions appears to be the preferable solution.

• 한국안전학회지
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• 제37권3호
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• pp.45-51
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• 2022

This paper focuses on a recently proposed asymmetric base-isolation coupling control system (ABiCS) for the vibration control of adjacent twin buildings. The ABiCS consists of inter-story diagonal dampers, a connecting damper between the two buildings, and a seismic isolation device at the base floor of one building. To investigate the control characteristics of ABiCS, a parametric study was performed by numerically simulating the 20-story twin buildings. In the parametric study, the control capacities of the inter-story diagonal dampers, connecting damper, and seismic isolation device were considered as varying parameters. The parametric study results indicate that the connecting damper between the two buildings reduces the responses of both buildings only at optimal or near-optimal capacity. In addition, adjusting the stiffness of the base isolation is found to be the most effective method for improving seismic performance and achieving cost-effectiveness. Accordingly, we presented a scenario-based performance improvement approach in which reducing the stiffness of the base isolation device could be an effective technique to improve the seismic performance of both buildings. However, note that checking the maximum allowable displacement of the base isolation device is essential.

• Structural Engineering and Mechanics
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• 제26권3호
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• pp.297-313
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• 2007

A preliminary performance-based seismic design methodology is proposed. The top yield displacement of the system is computed from these of the components, which are assumed constant. Besides, a simple procedure to evaluate the top yield displacement of frames is developed. Seismic demands are represented in the form of yield point spectra. The methodology is general, conceptually transparent, uses simple calculations based on first principles and is applicable to asymmetric systems. To consider a specific situation two earthquake levels, occasional and rare are considered. The advantage of an arbitrary assignment of strength to the different components to reduce eccentricities and improved the torsional response of the system is addressed. The methodology is applied to an asymmetric five story building, and the results are verified by push-over analysis and non linear dynamic analysis.

• Earthquakes and Structures
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• 제1권2호
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• pp.163-175
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• 2010

The vertical axis through the modal center of rigidity (m-CR) is used for interpreting the code torsional provisions in the design of eccentric multi-story building structures. The concept of m-CR has been demonstrated by the author in an earlier paper and the particular feature of this point is that when the vertical line of the centers of mass at the floor levels is passing through m-CR, minimum base torsion is developed. For this reason the aforesaid axis is used as reference axis for implementing the code provisions required by the equivalent static analysis. The study examines uniform mixed-bent-type multistory buildings with simple eccentricity, ranging from torsionally stiff to torsionally flexible systems. Using the results of a dynamic response spectrum analysis as a basis for comparisons, it is shown that the results of the code static design are on the safe side in torsionally stiff buildings, but unable to predict the required strength of bents on the stiff side of systems with a predominantly torsional response. Suggestions are made for improving the code provisions in such cases.