• Wind and Structures
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• 제14권2호
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• pp.113-131
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• 2011

Excessive wind-induced motion in tall buildings can cause discomfort, affect health, and disrupt the daily activities of the occupants of a building. Dynamic vibration absorbers such as the tuned mass dampers (TMDs) can be used to reduce the wind-induced motion below a specified tolerable serviceability limit state (SLS) criterion. This study investigates whether the same probability of not exceeding specified wind-induced motion levels can be achieved by torsionally sensitive structures without/with linear/nonlinear TMDs subjected to partially correlated wind forces, if they are designed to just meet the same SLS criterion. For the analyses, different structures and the uncertainty in the response, wind load and perception of motion is considered. Numerical results indicate that for structures that are designed or retrofitted without or with optimum linear TMDs and satisfying the same SLS criterion, their probability of exceeding the considered criterion is very consistent, if the inherent correlation between the wind forces is considered in design. However, this consistency deteriorates if nonlinear TMDs are employed. Furthermore, if the correlation is ignored in the design, in many cases a slightly unconservative design, as compared to the designed by considering correlation, is achieved.

• Geomechanics and Engineering
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• 제10권2호
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• pp.175-188
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• 2016

The construction of a new cavern modifies the state of stresses and displacements in a zone around the existing cavern. For multiple caverns, the size of this influence zone depends on the ground type, the in situ stress, the cavern span and shape, the width of the pillar separating the caverns, and the excavation sequence. Performances of underground twin caverns can be unsatisfactory as a result of either instability (collapse) or excessive displacements. These two distinct failures should be prevented in design. This study simulated the ultimate and serviceability performances of underground twin rock caverns of various sizes and shapes. The global factor of safety is used as the criterion for determining the ultimate limit state and the calculated maximum displacement around the cavern opening is adopted as the serviceability limit state criterion. Based on the results of a series of numerical simulations, simple regression models were developed for estimating the global factor of safety and the maximum displacement, respectively. It was proposed that a proper pillar width can be determined based on the threshold influence factor value. In addition, design charts with regard to the selection of the pillar width for underground twin rock caverns under similar ground conditions were also developed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.478-483
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• 2006

In this study, as a part of research which is to make 50kg NSI turnout of PC sleeper, the main objective of this study is the optimization of PC sleeper's section, the number of PS tension wire. For this purpose, the finite element analysis was conducted to evaluate the serviceability and the safety of NSI PC sleeper developed. Analytical results showed that PC sleeper adapted in this study satisfied not only serviceability criterion but also safety criterion.

• 한국경영과학회지
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• 제16권2호
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• pp.51-51
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• 1991

Recently financial institutions in Korea are experiencing an unfamiliar challenge in terms of their operational risk management due to the volatility of global financial market and the incessant development of new financial products. In this paper, we present an AHP(Analytic Hierarchy Process) model to evaluate the effectiveness of commercial softwares for risk management in banking. The AHP model considers software's performance. utility, serviceability and durability as major evaluation criteria. The weight of each criterion is generated by the questionnaire survey given to practitioners in risk management in domestic commercial banks.

• 경영과학
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• 제16권2호
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• pp.51-59
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• 1999

Recently financial institutions in Korea are experiencing an unfamiliar challenge in terms of their operational risk management due to the volatility of global financial market and the incessant development of new financial products. In this paper, we present an AHP(Analytic Hierarchy Process) model to evaluate the effectiveness of commercial softwares for risk management in banking. The AHP model considers software's performance. utility, serviceability and durability as major evaluation criteria. The weight of each criterion is generated by the questionnaire survey given to practitioners in risk management in domestic commercial banks.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.741-748
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• 2006

Seismic performance evaluation was conducted for four wind-designed concentrically braced steel highrise buildings in order to check the feasibility of designing steel highrise buildings per elastic seismic design criterion (or strength and stiffness solution) in the regions of strong wind and moderate seismicity. The pushover analysis results revealed that the wind-designed highrise buildings possess significantly increased elastic seismic capacity due to the overstrength resulting from the wind serviceability criterion. The strength demand-to-capacity study showed that, due to the wind-induced overstrength, highrise buildings with a slenderness ratio of larger than four or five can withstand elastically even the maximum considered earthquake at the performance level of immediate occupancy. Based on the analytical results of this study, practical elastic seismic design procedure for steel highrise buildings in the regions of moderate seismicity is proposed.

• KCI Concrete Journal
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• 제12권1호
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• pp.101-111
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• 2000

It has been a well known fact that buildings having inappropriate expansion joints in their spacings may be subject to exterior damages due to extensive cracks on the outer walls under service loads and structural damages due to excessive moment induced by temperature changes at ultimate load conditions. Unfortunately, consistent code provisions are unavailable regarding spacings of expansion joints from different foreign structural codes. And a more serious problem is that no quantitative measurements on spacings is given in our codes for building structures. In order to establish a rational guideline on the spacing of expansion joints, theoretical approaches are taken in this study. The developed theoretical formula is, then, converted to a design chart for structural designers' convenience in its use. The chart considers both service and ultimate load stages.

• 한국지반환경공학회 논문집
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• 제15권1호
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• pp.43-51
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• 2014

부등침하로 인한 각변위는 구조물의 안정성과 사용성에 영향을 미치는 중요한 요소 중 하나이다. 실무에서는 현재 Bjerrum이 제안한 각변위기준이 널리 사용되고 있다. 하지만 현재 도로 성토 현장에서 적용하고 있는 계측시스템은 구조물의 각변위를 적합하게 나타내지 못하고 있다. 이와 같은 문제는 충분하지 못한 계측 수, 부정확한 계측기 설치, 계측된 자료의 해석에 있어 각변위 기본개념의 잘못된 이해 등과 관련이 된다. 본 연구에서 도로 성토 현장에서 얻어진 데이터의 분석을 통해 이와 같은 문제점을 규명하였다. 도로 성토 현장에서 적용할 수 있는 자동화된 상대변위 계측시스템이라는 개선된 계측시스템을 제안하였다.

• Structural Engineering and Mechanics
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• 제77권1호
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• pp.89-102
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• 2021

Rapid construction of prefabricated bridges requires minimizing the field work of precast members and ensuring structural stability and constructability. In this study, we conducted experimental and analytical investigations of transverse joints of prefabricated T-girder bridge superstructures to verify the flexural performance and serviceability. In addition, we conducted parametric studies to identify the joint parameters. The results showed that both the segmented and continuous specimens satisfied the ultimate flexural strength criterion, and the segmented specimen exhibited unified behavior, with the flexural strength corresponding to that of the continuous specimen. The segmented specimens exhibited elastic behavior under service load conditions, and the maximum crack width satisfied the acceptance criteria. The reliability of the finite element model of the joint was verified, and parametric analysis of the convexity of the joint section and the compressive strength of the filler concrete showed that the minimum deflection and crack width occurred at a specific angle. As the strength of the filler concrete increased, the deflection and crack width decreased. However, we confirmed that the reduction in the crack width was hardly observed above a specific strength. Therefore, a design suitable for prefabricated bridges and accelerated construction can be achieved by improving the joint specifications based on the required criteria.

• Wind and Structures
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• 제32권4호
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• pp.283-292
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• 2021

Performance-based seismic design (PBSD) is currently used for retrofitting of older buildings and the design of new buildings. Whereas, application of performance-based design for wind load is still under development. The tendency has been in the codes to increase wind hazard based on recent recorded events. Since tall buildings are highly susceptible to wind load, necessity for developing a framework for performance-based wind design (PBWD) has intensified. Only a few guidelines such as ASCE (2019) provide information on using PBWD as an alternative for code prescriptive wind design. Though wind hazards, performance objectives, analysis techniques, and acceptance criteria are explained, no recommendations are provided for several aspects like how to select a proper level of wind hazard for each target performance criterion. This paper is an attempt to explain current design philosophy for wind and seismic loads and inherent connection between the components of PBSD for development of a framework for PBWD of tall buildings. Recognizing this connection, a framework for PBWD based on limits set for serviceability and strength is also proposed. Also, the potential for carrying out PBWD in line with ASCE 7-16 is investigated and proposed in this paper.