• Earthquakes and Structures
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• 제4권6호
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• pp.629-647
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• 2013

Loading protocols have been developed for quasi-static cyclic testing of structures and components. However, it is uncertain if protocols developed for conditions of intense ground shaking in regions of high seismicity would also be applicable to regions of low-moderate seismicity that are remote from the tectonic plate boundaries. This study presents a methodology for developing a quasi-static cyclic displacement loading protocol for experimental bracing evaluation of cold-formed steel stud shear walls. Simulations presented in the paper were based on conditions of moderate ground shaking (in Australia). The methodologies presented are generic in nature and can be applied to other regions of similar seismicity conditions (which include many parts of China, Korea, India and Malaysia). Numerous response time histories including both linear and nonlinear analyses have been generated for selected earthquake scenarios and site classes. Rain-flow cycle counting method has been used for determining the number of cycles at various ranges of normalized displacement amplitude. It is found that the number of displacement cycles of the loading protocol increases with increasing intensity of ground shaking (associated with a longer return period).

• 한국구조물진단유지관리공학회 논문집
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• 제17권5호
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• pp.13-20
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• 2013

구조물의 지진응답을 저감시키기 위하여 추가적인 감쇠기나 진동제어장치가 일반적으로 사용된다. 이때, 추가적인 감쇠장치의 제어성능은 대상구조물 특성의 변화 없이 검토된다. 본 연구에서는 구조물과 스마트 제어장치의 다목적 통합최적화를 수행하였고 스마트 최상층 면진시스템이 설치된 구조물의 구조물량 저감의 가능성을 분석하였다. 이를 위하여 20층 예제구조물이 사용되었으며 MR 감쇠기와 저감쇠 탄성베어링을 사용하여 스마트 면진시스템을 구성하였다. 중약진지역의 설계스펙트럼을 바탕으로 생성된 인공지진하중을 사용하여 구조해석을 수행하였다. 수치해석결과, 스마트 최상층 면진시스템이 중약진지역에 있는 구조물의 응답과 면진층 변위를 동시에 효과적으로 줄일 수 있는 것을 확인하였다. 본 연구에서 제안된 통합최적설계기법으로 구조물량 및 감쇠기 용량을 적절하게 줄이면서도 우수한 제어성능을 발휘하는 다양한 설계 대안을 제공할 수 있었다.

• Steel and Composite Structures
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• 제14권2호
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• pp.155-171
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• 2013

This study analytically evaluated the seismic performance of wind-designed diagrid tall steel buildings in regions of moderate/low seismicity and strong winds. To this end, diagrid tall steel buildings with varying wind exposure and slenderness ratio (building height-to-width ratio) conditions were designed to satisfy the wind serviceability criteria specified in the Korean Building Code and the National Building Code of Canada. A series of seismic analyses were then performed for earthquakes having 43- and 2475- year return periods utilizing the design guidelines of tall buildings. The analyses demonstrated the good seismic performance of these wind-designed diagrid tall steel buildings, which arises because significant overstrength of the diagrid system occurs in the wind design procedure. Also, analysis showed that the elastic seismic design process of diagrid tall steel buildings might be accepted based on some wind exposures and slenderness ratios.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.101-104
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• 2005

This study is to develop detailing guidelines based on ductility demand for reinforced concrete bridge columns in areas of low to moderate seismicity. The current seismic design criteria of the Korea Design Specifications for Highway Bridge (KDSHB 2005) adopted the seismic design concept and requirements of the AASHTO specifications. In order to obtain full ductile behavior under seismic loads, i.e. when applied seismic force is larger than design flexural strength of column section, a response modification factor (R=3 or 5) is used. In moderate seismicity regions, however, adopting the full ductility design concept sometimes results in construction problems due to reinforcement congestion. The objective of this paper is to suggest a new simplified seismic design of reinforced concrete bridge columns for moderate seismicity regions.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.155-162
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• 2002

A technique for the seismic reliability evaluation of electric power transmission systems(EPTS) adapted to ground motion characteristics of Korea has been developed to evaluate reliability indices corresponding to the whole system and to each node within. A network model with nodes and links for EPTS has been established, and a seismic substation-fragility curve obtained from seismic fragilities of power system facilities has been derived. A point source model, the doubly truncated Gutenberg-Richter relationship, and earthquake intensity attenuation formula have been applied to simulate seismic events. Using Monte-Carlo simulation method, the seismic reliability of EPTS is evaluated and, it appeared that seismic effect on EPTS in low and moderate seismicity regions has to be considered.

• 한국지진공학회논문집
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• 제22권2호
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• pp.77-86
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• 2018

This study develops an empirical prediction equation of spectral acceleration responses of earthquakes which can induce structural damages. Ground motion records representing hazards of low-to-moderate seismic regions were selected and organized with several influential factors affecting the response spectra. The empirical equation and estimator coefficients for acceleration response spectra were then proposed using a robust nonlinear optimization coupled with a regression analysis. For analytical verification of the prediction equation, response spectra used for low-to-moderate seismic regions were estimated and the predicted results were comparatively evaluated with measured response spectra. As a result, the predicted shapes of response spectra can simulate the graphical shapes of measured data with high accuracy and most of predicted results are distributed inside range of correlation of variation (COV) of 30% from perfectly correlated lines.

• Structural Engineering and Mechanics
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• 제39권4호
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• pp.559-578
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• 2011

In regions of high seismic risk, high-strength concrete (HSC) columns of tall buildings are designed to be fully ductile during earthquake attack by providing substantial amount of confining steel within the critical region. However. in areas of low to moderate seismic risk, the same provision of confining steel is too conservative because of the reduced seismic demand. More critically, it causes problematic steel congestion in the beam-column joints and column critical region. This will eventually affect the quality of concrete placing owing to blockage. To relieve the problem, the confining steel in the critical region of HSC columns located in low to moderate seismicity regions can be suitably reduced, while maintaining a limited ductility level. Despite the advantage, there are still no guidelines developed for designing limited ductility HSC columns. In this paper, a formula for designing limited ductility HSC columns is presented. The validity of the formula was verified by testing half-scale HSC columns subjected to combined high-axial load and flexure, in which the confining steel was provided as per the proposed formula. From the test results, it is evident that the curvature ductility factors obtained for all these columns were about 10, which is the generally accepted level of limited ductility.

• 한국지진공학회논문집
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• 제19권5호
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• pp.247-256
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• 2015

This paper briefly introduces the design seismic loads in Korea (KBC 2009). Then, over 10,000 recorded earthquake ground accelerograms, with their magnitude ranging from 4.0 to 8.0 and their epicentral distance ranging from 0 to 200 km, were used to examine the appropriateness of seismic load defined in Korea known as a low-to-moderate seismicity region. The following conclusions are drawn based on the results: (1) The effective peak ground accelerations (EPA) of recorded earthquake accelerograms under $M{\leq}6.0$ and $R{\geq}15km$ appear to be less than that of MCE in Korea for all site conditions defined in KBC 2009. (2) The design spectrum (two-thirds of the intensity of MCE) in KBC 2009 is comparable to those of earthquake records in the magnitude 6 - 7 and the epicentral distance less than 50 km. Therefore, (3) the intensity of Korean design earthquake is considered to be overly high since the Korea peninsula is generally conceived to be a low-seismicity region.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.305-312
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• 1999

A four-story reinforced concrete frame building model is designed for the gravity loads. only Static nonlinear pushover analyses are performed in two orthogonal horizontal directions. The overall capacity curves are converted into ADRS spectra and compared with demand spectra. At several points the deformed shape moment and shear distribution are calculated. It is observed that the seismic capacity may not meet the design requirements in soft soil condition and may collapse in MCE. It is concluded that limited but adequate amount of ductility need be provided in the seismic design in low to moderate seismicity regions.

• Steel and Composite Structures
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• 제18권1호
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• pp.121-134
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• 2015

This paper is to investigate the potentials of the elastic seismic design of twisted high-rise steel diagrid frame buildings in the strong wind and moderate/low seismicity regions. First, the prototypes of high-rise steel diagrid frames with architectural plans that have a twist angle of 0 (regular-shaped), 1, and 2 degrees were designed to resist wind. Then, the effects of the twist angle on the estimated quantities and structural redundancies of the diagrid frames were examined. Second, the seismic performance of the wind-designed prototype buildings under a low seismicity was evaluated. The response spectrum analysis was conducted for the service level earthquake (SLE) having 43-year return period and the maximum considered earthquake (MCE) having 2475-year return period. The evaluation resulted that the twisted high-rise steel diagrid frames resisted the service level earthquake elastically and most of their diagrid members remained elastic even under the maximum considered earthquake.