• 한국구조물진단유지관리공학회 논문집
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• 제20권1호
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• pp.72-84
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• 2016

종래 브레이스시스템은 횡력저항 및 층변위제어에 효율적이며 골조물량 감소에 따른 경제성이 향상되어 일반적인 강구조 횡력저항시스템으로 적용되고 있다. 그러나 압축측에서 항복응력에 도달하기 전 가새의 좌굴이 발생하여 충분한 내력을 발휘하지 못하고, 내력열화형의 이력거동으로 불안정상태가 된다. 좌굴에 의한 내력저하 개선시스템으로 중심재를 구속하여 좌굴방지가 가능한 비좌굴가새는 심재의 항복 이후에도 안정적인 이력특성을 나타내어 종래 브레이스에 비하여 에너지흡수능력이 우수하다. 최근 10년간 미국, 일본 및 대만에서 매우 다양한 형상의 비좌굴가새가 제안되었으나, 기존의 실험연구에서는 그 형상이 매우 제한적인 경향을 보이고 있다. 본 연구에서는 조립형 Precast RC 보강재를 가지는 비좌굴가새를 제작하고 이력특성을 평가하기 위한 부재실험을 수행하였다. 또한 실험결과를 AISC(2005)의 요구조항과 비교하였다.

• 콘크리트학회논문집
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• 제12권6호
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• pp.119-126
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• 2000

Reinforced concrete structural walls are widely known to provide an efficient lateral load resistance and drift control. However, many reported researches on them are mostly limited to the RC structural walls reinforced according to seismic details. When the pushover analysis technique is used for the prediction of inelastic behavior of frame-wall structures for the seismic evaluation of existing buildings having non-seismic details, the reliability of this analysis method should be checked by the test results. The objective of this study is to verify the correlation between the experimental and analytical responses of a high-rise reinforced concrete frame-wall structure having non-seismic details by using DRAIN-2DX program[11] and the test results performed previously[1]. It is concluded that the behavior of the frame-wall model is mainly affected by the fixed-end rotation(uplift at base) and bending deformation of the wall and that the analysis with the LINKS model[10] in DRAIN-2DX describes them with good reliability.

• Wind and Structures
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• 제20권5호
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• pp.623-642
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• 2015

Several international codes have been developed for evaluating wind loads on structures; however, the wind structure interaction could not be accurately captured by these codes due to the gusty nature of wind and the dynamic behavior of structures. Therefore, the alternative wind tunnel testing was introduced. In this study, an introduction to the available approaches for wind load calculations for tall buildings was presented. Then, a comparative study between different codes: the Egyptian code, ECP 201-08, ASCE 7-05, BS 6399-2, and wind tunnel test results was conducted. An investigation has been carried out on two case studies tall buildings located within the Arabian Gulf region. Numerical models using (ETABS) software were produced to obtain the relation between codes analytical values and wind tunnel experimental test results for wind loads in the along and across wind directions. Results for the main structural responses including stories forces, shears, overturning moments, lateral displacements, and drifts were presented graphically in order to give clear comparison between the studied methods. The conclusions and recommendations for future works obtained from this research are finally presented to help improving Egyptian code provisions and show limitations for different cases.

• 한국전산구조공학회논문집
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• 제23권5호
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• pp.465-473
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• 2010

건물의 높이와 세장비가 증가함에 따라 건물의 최대 횡변위와 풍응답 가속도와 같은 사용성 요구조건을 만족시키는 것이 고층건물 구조설계에 있어서 중요한 설계요소가 되고 있다. 풍응답 가속도는 거주자에게 불쾌함을 유발시키는 직접적인 원인이 되지만, 초기 구조 설계단계에서 구조 설계자가 풍응답을 조절할 수 있는 실용적인 방법은 개발되어 있지 못하다. 본 연구에서는 재분배기법을 이용하여 건물의 강성을 조절함으로써 고층건물의 풍응답 가속도를 조절할 수 있는 방법을 제안하였다. ASCE 7-02, NBCC 95, ISO 6897 등의 설계 코드 및 기준에 의하면 고층건물의 풍응답 가속도는 1차 고유주기에 반비례한다는 사실에 근거하여 본 연구에서는 물량을 재분배하여 건물의 1차 고유주기를 조절함으로서 풍응답 가속도를 조절하는 실용적 풍응답 가속도 조절 설계법을 제안한다. 제안된 설계법은 42층 건물의 풍응답 가속도 조절 설계에 적용하여 그 적용성과 효율성을 평가하였다.

• Earthquakes and Structures
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• 제15권5호
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• pp.529-540
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• 2018

The influences of initial damage paths and aftershock (AS) spectral shape on the assessment of AS collapse fragility are investigated. To do this, a four-story ductile reinforced concrete (RC) frame structure is employed as the study case. The far-field earthquake records recommended by FEMA P695 are used as AS ground motions. The AS incremental dynamic analyses are performed for the damaged structure. To examine the effect of initial damage paths, a total of six kinds of initial damage paths are adopted to simulate different initial damage states of the structure by pushover analysis and dynamic analysis. For the pushover-based initial damage paths, the structure is "pushed" using either uniform or triangle lateral load pattern to a specified damage state quantified by the maximum inter-story drift ratio. Among the dynamic initial damage paths, one single mainshock ground motion or a suite of mainshock ground motions are used in the incremental dynamic analyses to generate a specified initial damage state to the structure. The results show that the structure collapse capacity is reduced as the increase of initial damage, and the initial damage paths show a significant effect on the calculated collapse capacities of the damaged structure (especially at severe damage states). To account for the effect of AS spectral shape, the AS collapse fragility can be adjusted at different target values of ${\varepsilon}$ by using the linear correlation model between the collapse capacity (in term of spectral intensity) and the AS ${\varepsilon}$ values, and coefficients of this linear model is found to be associated with the initial damage states.

• 국제초고층학회논문집
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• 제7권1호
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• pp.17-32
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• 2018

This paper explores the function of a structural skin with an embossed surface applicable to use for tall building structures. The major diagrid system with a secondary embossed surface structure provides an enhanced perimeter structural system by increasing tube section areas and reduces aerodynamic loads by disorienting major organized structure of winds. A parametric study used to investigate an optimized configuration of the embossed structure revealed that the embossed structure has a structural advantage in stiffening the structure, reducing lateral drift to 90% compared to a non-embossed diagrid baseline model, and results of wind load analysis using computational fluid dynamics, demonstrated the proposed embossed system can reduce. The resulting undulating embossed skin geometry presents both opportunities for incorporating versatile interior environments as well as unique challenges for daylighting and thermal control of the envelope. Solar and thermal control requires multiple daylighting solutions to address each local façade surface condition in order to reduce energy loads and meet occupant comfort standards. These findings illustrate that although more complex in geometry, architects and engineers can produce tall buildings that have less impact on our environment by utilizing structural forms that reduce structural steel needed for stiffening, thus reducing embodied $CO^2$, while positively affecting indoor quality and energy performance, all possible while creating a unique urban iconography derived from the performance of building skin.

• International Journal of Automotive Technology
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• 제6권2호
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• pp.183-190
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• 2005

During normal operating conditions, a motor vehicle is constantly subjected to a variety of forces, which can adversely affect its straight-ahead motion performance. These forces can originate both from external sources such as wind and road and from on-board sources such as tires, suspension, and chassis configuration. One of the effects of these disturbances is the phenomenon of vehicle lateral-drift during straight-ahead motion. This paper examines the effects of road crown, tires, and suspension on vehicle straight-ahead motion. The results of experimental studies into the effects of these on-board and external disturbances are extremely sensitive to small changes in test conditions and are therefore difficult to guarantee repeatability. This study was therefore conducted by means of computer simulation using a full vehicle model. The purpose of this paper is to gain further understanding of the straight-ahead maneuver from simulation results, some aspects of which may not be obtainable from experimental study. This paper also aims to clarify some of the disputable arguments on the theories of vehicle straight-ahead motion found in the literature. Tire residual aligning torque, road crown angle, scrub radius and caster angle in suspension geometry, were selected as the study variables. The effects of these variables on straight-ahead motion were evaluated from the straight-ahead motion simulation results during a 100m run in free control mode. Examination of vehicle behavior during straight-ahead motion under a fixed control mode was also carried out in order to evaluate the validity of several disputable arguments on vehicle pull theory, found in the literature. Finally, qualitative comparisons between the simulation results and the test results were made to support the validity of the simulation results.

• 한국지진공학회논문집
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• 제27권5호
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• pp.203-211
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• 2023

For fast-built and safe precast concrete (PC) construction, the dry mechanical splicing method is a critical technique that enables a self-sustaining system (SSS) during construction with no temporary support and minimizes onsite jobs. However, due to limited experimental evidence, traditional wet splicing methods are still dominantly adopted in the domestic precast industry. For PC beam-column connections, the current design code requires achieving emulative connection performances and corresponding structural integrity to be comparable with typical reinforced concrete (RC) systems with monolithic connections. To this end, this study conducted the standard material tests on mechanical splices to check their satisfactory performance as the Type 2 mechanical splice specified in the ACI 318 code. Two PC beam-column connection specimens with dry mechanical splices and an RC control specimen as the special moment frame were subsequently fabricated and tested under lateral reversed cyclic loadings. Test results showed that the seismic performances of all the PC specimens were fully comparable to the RC specimen in terms of strength, stiffness, energy dissipation, drift capacity, and failure mode, and their hysteresis responses showed a mitigated pinching effect compared to the control RC specimen. The seismic performances of the PC and RC specimens were evaluated quantitatively based on the ACI 374 report, and it appeared that all the test specimens fully satisfied the seismic performance criteria as a code-compliant special moment frame system.

• 콘크리트학회논문집
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• 제26권2호
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• pp.125-133
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• 2014

이 연구에서는 볼트접합 및 프리스트레스를 적용한 프리캐스트 콘크리트 보-기둥 외부접합부의 내진 및 구조적 성능을 평가하였다. 총 5개의 보-기둥 외부접합부 실험체를 제작하고 보 단부에 변위제어 방식으로 반복하중을 가하며 실험을 수행하였다. 이 연구의 결과를 근거로 다음과 같은 결론을 얻을 수 있었다. 완전 건식공법이 적용된 PC 접합부는 완전 습식공법이 적용된 RC 접합부보다 에너지소산이나 핀칭현상에 있어서 불리한 거동을 보였지만 이는 설계과정에서 의도된 현상이며, 횡변형 능력에 있어서는 우수한 결과를 보였다. 또한 층간변위비 4%까지 횡하중 저항성능의 손실이 발생하지 않았고 매설용너트에 항복이 집중되는 메커니즘을 보이는 점으로 미루어 볼 때 개발된 접합부는 외부접합부 횡저항시스템으로서 적합한 것으로 사료된다. 추가적인 프리스트레스는 PC 접합부의 과도한 핀칭현상 방지 및 접합부 균열제어에 효과적이었으며 PC 접합부의 전체적인 내진성능을 향상시켰다.

• 한국강구조학회 논문집
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• 제26권6호
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• pp.571-579
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• 2014

고층건축물의 수평변위 제어에 필요한 브레이스는 구조물의 경제성 확보를 위해 주로 새장한 부재를 설치하여 인장하중에 저항하도록 하는 경우가 많다. 하지만, 브레이스에 압축하증이 작용할 경우에는 부재가 하중에 저항하지 않는 부재로 상정하여 설계되고 있다. 이는 브레이스에 압축하중이 작용할 경우 부재의 탄성좌굴이 발생하게 되어 급격히 내하력을 잃어버리게 되기 때문이다. 이러한 문제를 해결하기 위해 많은 연구가 이루어져 왔으며, 그중 대표적인 것이 응력제한장치라 할 수 있다. 응력제한장치는 세장한 부재가 압축하중에 의해 탄성좌굴이 발생하기 전에 부재가 항복하여 안정적인 거동을 유도하는 것을 목적으로 하고 있다. 본 논문에서는 응력제한장치로서 절판방식을 제안하고 실험과 유한요소 해석을 수행하였다. 실험은 절판단면의 경사각을 변수로 하여, FLD장치 및 FLD를 장착한 부재에 대한 압축실험 및 해석을 진행하였다. 그 결과 절판방식의 실험체는 항복 후 소성영역에서 내력의 큰 저하 없이 안정적인 거동을 나타내고 있어 응력제한방식으로서 유효함이 확인되었다.