• Wind and Structures
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• 제24권1호
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• pp.59-78
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• 2017

Non-stationarity and non-Gaussian property are two of the most important characteristics of wind. These two features are studied in this study based on wind speed records measured at different heights from a 325 m high meteorological tower during the synoptic wind storms. By using the time-frequency analysis tools, it is found that after removing the low frequency trend of the longitudinal wind, the retained fluctuating wind speeds remain to be asymmetrically non-Gaussian distributed. Results show that such non-Gaussianity is due to the weak-stationarity of the detrended fluctuating wind speed. The low frequency components of the fluctuating wind speeds mainly contribute to the non-zero skewness, while distribution of the high frequency component is found to have high kurtosis values. By further studying the decomposed wind speed, the mechanisms of the non-Gaussian distribution are examined from the phase, turbulence energy point of view.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.183-194
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• 2017

This paper presents the experimental investigation into a new type of steel-concrete hybrid outrigger system developed for the high-rise building structure. The steel truss is embedded into the reinforced concrete outrigger wall, and both the steel truss and concrete outrigger wall work compositely to enhance the overall structural performance of the tower structures under extreme loads. Meanwhile, metal dampers of low-yield steel material were also adopted as a 'fuse' device between the hybrid outrigger and the column. The damper is engineered to be 'scarified' and yielded first under moderate to severe earthquakes in order to protect the structural integrity of important structural components of the hybrid outrigger system. As such, not brittle failure is likely to happen due to the severe cracking in the concrete outrigger wall. A comprehensive experimental research program was conducted into the structural performance of this new type of hybrid outrigger system. Studies on both the key component and overall system tests were conducted, which reveal the detailed structural response under various levels of applied static and cyclic loads. It was demonstrated that both the steel bracing and concrete outrigger wall are able to work compositely with the low-yield steel damper and exhibits both good load carrying capacities and energy dispersing performance through the test program. It has the potential to be applied and enhance the overall structural performance of the high-rise structures over 300 m under extreme levels of loads.

• 국제초고층학회논문집
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• 제4권2호
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• pp.117-125
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• 2015

A vertical city with multifunctional land use turns out to be the most viable solution for an urban condition characterized by increasing density due to population expansion, topographical limitation of buildable land, economic development and the pursuit for collective sustainable living, such as in Hong Kong. This paper presents initial research results from a study on the chronological and typological evolution of tall buildings in the city, from the climate-responsive verandah typology to the mixed-use hyper-commercial podium and residential tower typologies that predominate today, to the ultimate formation of a vertical city. Case studies and surveys have focused on the development of this building typology throughout the decades since the 1920s, substantiating a discussion on the subjective and objective factors contributing to a genesis of the vertical city phenomenon in Hong Kong. The discussion will engage, under the notion of the vertical city, on how residents and visitors adapt to the growing density of the city, and how they accustom themselves to the changing urban morphology over time. Advantages such as high efficiency, spaces savings, time convenience, etc.; and disadvantages such as deficiency in livability, incompatibility of uses, environmental health deficiencies, etc.; serve as a reference for other cities in need of high-density planning due to population and economic growth.

• 한국물환경학회지
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• 제18권2호
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• pp.221-228
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• 2002

Abundant growth of algae in raw water sources caused by eutrophication brings about significant side effects on water supply, such as taste and order problem, oxygen depletion, toxic material secretion, and filter clogging problem in water treatment process, etc. The purpose of this research is to remove the algae and phosphorus compounds in the Pal-dang reservoir promptly by using the upflow filtration system with coagulant addition. The filter tower consisted of sand media and sieve filter with air back-washing process. By using coagulation and filtration with $132{\mu}m$ pore size filter, about 55% and 70% of algae and phosphorus compounds were removed respectively. The experimental conditions were as follows; head loss of 0.2m, linear velocity of 200m/day, and filtration flux of 1000($L/m^2/day$). In the case of filtration with cartridge type filter of $25{\mu}m$ pore size, the filtration flux was about 7800 LMH, and the removal ratios of COD, SS, T-P, and Chlo-a. were 61%, 99%, 54%, and 98%, respectively. However, high pressure air back-washing process with should be required for the maintenance of such high filtration flux.

• Wind and Structures
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• 제36권4호
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• pp.263-275
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• 2023

As a new kind of construction facility for high rise buildings, the integral steel platform scaffold system (ISPS) consisting of the steel skeleton and suspended scaffold faces high wind during the construction procedure. The lattice structure type and existence of core tubes both make it difficult to estimate the wind load and calculate the wind-induced responses. In this study, an aeroelastic model with a geometry scale ratio of 1:25 based on the ISPS for Shanghai Tower, with the representative square profile, is manufactured and then tested in a wind tunnel. The first mode of the prototype ISPS is a torsional one with a frequency of only 0.68 Hz, and the model survives under extreme wind speed up to 50 m/s. The static wind load and wind vibration factors are derived based on the test result and supplementary finite element analysis, offering a reference for the following ISPS design. The spacer at the bottom of the suspended scaffold is suggested to be long enough to touch the core tube in the initial status to prevent the collision. Besides, aerodynamic wind loads and cross-wind loads are suggested to be included in the structural design of the ISPS.

• 한국강구조학회 논문집
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• 제26권4호
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• pp.299-309
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• 2014

HSA800은 건축구조용 고성능 강재로서 KS규격에 항복강도 650MPa-770MPa, 인장강도 800MPa-950MPa를 가지며 항복비(항복강도/인장강도) 또한 0.85이하로 제한되어있으며 TMCP 기법으로 제조되어 뛰어난 용접성을 나타내는 특징이 있다. 본 연구에서는 국내 최초의 초고층 빌딩인 롯데월드타워의 메가 구조부재를 대상으로 고강도 강재 적용시 구조물 안전성의 변동사항 및 시공성 개선 등을 검토하여 경제적 설계를 위한 대안을 제시하는 것을 목적으로 한다. 대상 부재로는 아웃리거 코어월 매립부 상/하현재, 벨트트러스, 외곽 철골기둥이 선정되었다. 원설계 단면을 등가 도강도 강재 단면으로 환산하여 두께를 결정한 후 중력저항모델, 횡력저항모델, 연쇄붕괴 모델을 구조해 석시뮬레이션을 통하여 성능을 비교 평가하였다. 그 결과 횡강성에 영향을 주지 않는 부재는 고강도 강재 적용이 가능하며 원설계 대비 약 1100톤의 물량 절감 효과가 있었다. 따라서, 고강도 강재를 사용하면 부재 두께를 줄일 수 있으므로 부재 제작성 및 시공성이 향상될 수 있을 것으로 기대된다.

• Earthquakes and Structures
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• 제19권5호
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• pp.331-345
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• 2020

The multi-story timber structure with high platform base is one of the important architectural types in the traditional Chinese buildings. To study the dynamic characteristics and seismic responses on this kind of traditional structure, the 3-D finite element models of Xi'an drum tower which included the high platform base, upper timber structure and whole structure was established considering the structural form and material performance parameters of the structure in this study. By the modal analysis, the main frequencies and mode shapes of this kind of traditional building were obtained and investigated. The three kinds of earthquake excitations included El-Centro wave, Taft wave and Lanzhou wave were separately imposed on the upper timber structure model and the overall structure model, and the seismic responses on the tops of columns were analyzed. The results of time history analysis show that the seismic response of the upper timber structure is obviously amplified by high platform base. After considering the effect of high platform base, the mean value on the lateral displacement increments of the top column in the overall structure is more than 20.478% and the increase of dynamic coefficients was all above 0.818 under the above three different earthquake excitations. Obviously, it shows that the existence of high platform base has a negative influence on the seismic responses of upper timber structure. And the high platform base will directly affect the safety of the upper timber structure. Therefore, the influence of high platform base on the dynamic response of its upper timber structure cannot be neglected.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.703-715
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• 2002

타워팰리스 3차 현장은 국내에서 현존하는 건축물로서 가장 높은 63빌딩보다 약 30m 정도 더 높은 초고층 주상 복합건물이다. 초고층 건축현장에는 일반현장과는 다른 시공기술과 기법이 적용되는 바, 당 현장에는 기존의 타워팰리스 1차와 2차에 적용되었던 초고층 시공기술을 기반으로 좀 더 발전된 시공기술과 공정관리기법을 적용하여 선진국에 버금가는 속도로 공사가 추진되고 있다. 당 현장에 적용된 여러 시공기술 중에서 콘크리트와 관련된 주요 기술은 1) Mat 기초에 적용된 무다짐(또는 고유동화)콘크리트, 2) Mat 기초에 적용된 Closed Pipe Cooling System, 3) Core ACS Form에 적용된 고강도 콘크리트, 4) 기둥에 적용한 800 kg/$m^2$ 초고강도 콘크리트, 5) 스포츠동 기둥에 적용될 CFT용 고유동화 콘크리트, 6) 주차램프 바닥의 조면처리용 섬유보강콘크리트 등이다.

• 한국유체기계학회 논문집
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• 제19권6호
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• pp.14-18
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• 2016

Multi-MW wind turbines have very large blades over 40~50 m in length. Some factors like wind shear and tower shadow make an effect on asymmetric loads on the blades. Larger asymmetric loads are produced as the length of blade is getting longer. In this paper, a 2 MW on-shore wind turbine is considered and variations of thrust on 3 blades and rotor hub under wind shear are calculated by using a commercial Bladed S/W and dynamic properties of the thrust variations are investigated. It is shown that the amplitude of the asymmetric thrust on each blade under wind shear is getting larger as the wind speed increases, the frequency of the thrust variation on each blade is same as the one of rotor speed, and the frequency of the thrust variation at rotor hub is 3 times as high as the one of rotor speed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.486-490
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• 2009

In order to investigate the offshore wind resources, the "QuikSCAT Level 3" data by the QuikSCAT satellite was analyzed from Jan 2000 to Dec 2008. QuikSCAT satellite is a specialized device for a microwave scatterometer that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed measured at 10 m above from the sea surface as extrapolated to the hub height by using the power law model. It has been found that the high wind energy prevailing in the south sea and the east sea of the Korean peninsula. From the limitation of seawater depth for piling the tower and archipelagic environment around the south sea, the west and the south-west sea are favorable to construct the large scale wind farm. Wind map and monthly variation of wind speed are investigate at the positions.