• 국제초고층학회논문집
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• 제3권1호
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• pp.73-79
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• 2014

In recent years, the performance requested for which an ultra-high rise buildings is diversified. Large spans are designed in order to gain wide workspace. Column positions are shifted in middle stories to provide space different from neighboring floors. Moreover, in the bottom layers of the building, it is becoming more important to expand freedom to plan flexibility such as creating publically opened wide atria that gives attractive free space. Earthquake-proof criteria is also changing not only human life protection deign but also a design that allows functional continuity. In order to achieve thee needs, as one of technology, we have developed ultra-high strength concrete filled tubular (CFT) columns of the box section that combine ultra-high strength concrete with specified strength of $150N/mm^2$ and ultra-high strength steel material with tensile strength of $780N/mm^2$. In this paper, the outline of development of an ultra-high strength CFT column is reported. Also, the structural design of the ultra-high-rise building using the CFT columns is reported.

• Steel and Composite Structures
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• 제32권5호
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• pp.583-594
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• 2019

In recent years, composite concrete-filled steel tubular (CFST) members have been widely utilized in framed building structures like beams, columns, and beam-columns since they have significant advantages such as reducing construction time, improving the seismic performance, and possessing high ductility, strength, and energy absorbing capacity. This paper presents a new composite joint - the composite CFST beam-column joint in which the CFST member is used as the beam. The main components of the proposed composite joint are steel H-beams, CFST beams welded with the steel H-column, and a reinforced concrete slab. The steel H-beams and CFST beams are connected with the concrete slab using shear connectors to ensure composite action between them. The structural performance of the proposed composite joint was evaluated through an experimental investigation. A three-dimensional (3D) finite element (FE) model was developed to simulate this composite joint using the ABAQUS/Explicit software, and the accuracy of the FE model was verified with the relevant experimental results. In addition, a number of parametric studies were made to examine the effects of the steel box beam thickness, concrete compressive strength, steel yield strength, and reinforcement ratio in the concrete slab on the proposed joint performance.

• 국제초고층학회논문집
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• 제7권4호
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• pp.397-408
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• 2018

In a recent tragic fire incident, the Plasco Tower collapsed after an intense outburst of fire lasting for three and a half hours and claiming the lives of 16 firefighters and 6 civilians. This paper will present continuing collaborative work between Hong Kong Polytechnic University and Queen's University in Canada to model the progressive collapse of the tower. The fire started at the 10th floor and was observed to have travelled along the floor horizontally and through the staircase and windows vertically. Plasco Tower was steel structure and all the steel sections were fabricated by welding standard European channel or angle profiles and no fire protection was applied. Four internal columns carried the loads transferred by the primary beams, and box columns were constructed along the perimeter of the building as a braced tube for resisting seismic loading. OpenSees fibre-based sections and displacement-based beam-column elements are used to model the frames, while shell elements are used for the reinforced concrete floor slabs. The thermal properties and elevated temperature mechanical properties are as recommended in the Eurocodes. The results in this preliminarily analysis are based on rough estimations of the structure's configuration. The ongoing work looks at modeling the Plasco Tower based on the most accurate findings from reviewing many photographs and collected data.

• 한국강구조학회 논문집
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• 제26권4호
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• pp.289-297
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• 2014

본 연구에서는 고강도강재(HSA800)의 단주 편심압축실험을 통해 휨-압축 부재의 강도를 평가하였다. 편심압축실험은 축력비에 따라 휨-압축의 조합력을 받는 부재의 P-M 상관관계를 알아보기 위해 HSA800강재의 각형강관과 H형강을 대상으로 실험을 수행하였으며, 가력 편심거리를 조정하여 다양한 P-M 조합에 대해 강도평가 실험을 수행하였다. 실험결과 실험최대 평균응력은 국부좌굴에 의한 최대내력이 결정된 실험체에 대해서는 판폭두께비가 증가함에 따라 감소하는 경향을 보였다. 발현강도의 여유는 축력이 낮을수록 상대적으로 휨강도에 대해 큰 마진을 보이고 있었고, 실험체 모두 현행 설계기준의 P-M 상관관계를 안전측으로 충족하였다.

• International Journal of Concrete Structures and Materials
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• 제2권2호
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• pp.91-98
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• 2008

Curved bridges are important components of a highway transportation network for connecting local roads and highways, but very few data have been collected in terms of their field performance. This paper presents two-years monitoring and system identification results of a curved concrete box-girder bridge, the West St. On-Ramp, under ambient traffic excitations. The authors permanently installed accelerometers on the bridge from the beginning of the bridge life. From the ambient vibration data sets collected over the two years, the element stiffness correction factors for the columns, the girder, and boundary springs were identified using the back-propagation neural network. The results showed that the element stiffness values were nearly 10% different from the initial design values. It was also observed that the traffic conditions heavily influence the dynamic characteristics of this curved bridge. Furthermore, a probability distribution model of the element stiffness was established for long-term monitoring and analysis of the bridge stiffness change.

• 한국지진공학회논문집
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• 제22권5호
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• pp.271-280
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• 2018

This paper presents a framework for developing aftershock fragility curves for reinforced concrete bridges initially damaged by mainshocks. The presented aftershock fragility is a damage-dependent fragility function, which is conditioned on an initial damage state resulting from mainshocks. The presented framework can capture the cumulative damage of as-built bridges due to mainshock-aftershock sequences as well as the reduced vulnerability of bridges repaired with CFRP pier jackets. To achieve this goal, the numerical model of column jackets is firstly presented and then validated using existing experimental data available in literature. A four-span concrete box-girder bridge is selected as a case study to examine the application of the presented framework. The aftershock fragility curves are derived using response data from back-to-back nonlinear dynamic analyses under mainshock-aftershock sequences. The aftershock fragility curves for as-built bridge columns are firstly compared with different levels of initial damage state, and then the post-repair effect of FRP pier jacket is examined through the comparison of aftershock fragility curves for as-built and repaired piers.

• BMB Reports
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• 제40권6호
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• pp.845-852
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• 2007

The highly evolved flowers of orchids have colorful sepals and fused columns that offer an opportunity to discover new genes involved in floral development in monocotyledon species. In this investigation, we cloned and characterized the homologous PISTALLATA-like (PI-like) gene PhPI15 ($\underline{Ph}alaenopsis$ $\underline{PI}$ STILLATA # $\underline{15}$), from the Phalaenopsis hybrid cultivar. The protein sequence encoded by PhPI15 contains a typical PI-motif. Its sequence also formed a subclade with other monocot PI-type genes in phylogenetic analysis. Southern analysis showed that PhPI15 was present in the Phalaenopsis orchid genome as a single copy. Furthermore, it was expressed in all the whorls of the Phalaenopsis flower, while no expression was detected in vegetative organs. The flowers of transgenic tobacco plants ectopically expressing PhPI15 showed male-sterile phenotypes. Thus, as a Class-B MADS-box gene, PhPI15 specifies floral organ identity in orchids.

• Steel and Composite Structures
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• 제10권6호
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• pp.489-500
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• 2010

The rigid connections of I-beams to Rectangular Hollow Sections (RHS) in steel structures usually behave as semi-rigid connection. This behavior is directly related to the column face deformation. The deformation in the wall of RHS column in the connection zone causes a relative rotation between beam end and column axis, which consequently reduces the rigidity of beam-column connection. In the present paper, the percentages of connection rigidity reduction for serviceability conditions are evaluated by using the finite element analysis. Such percentages for RHS columns without internal stiffeners are considerable, and can be calculated from presented graphs.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.169-170
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• 2009

CFT 구조는 강재 또는 철근콘크리트로 이루어진 일반 구조용 부재와 비교해서 많은 이점을 가진다. 강재 박스와 콘크리트의 구속효과에 의한 전체구조물의 연성도, 강성 및 하중지지능력의 증가 때문에 CFT 구조는 기둥 부재에 광범위하게 적용되고 있다. 이러한 CFT 구조의 장점들 때문에 최근들어 CFT 부재는 거더부재로 교량구조물에 확대 적용되고 있다. 본 연구의 목적은 CFT 구조, 아치형상 및 긴장재로 이루어진 CFTA 거더교의 해석모델을 개발하고 이를 적용한 설계법을 제안하기 위함이다.

• 한국건설관리학회논문집
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• 제5권5호
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• pp.183-192
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• 2004

현재 국내에도 건물의 특성에 알맞은 가변적이며 대공간 확보가 가능하고 사용부재의 두께가 수mm에서 100mm에 이르는 극후판 두께의 건축 철골구조의 건축물 및 Box형 강재교량으로 구축되는 사례가 증가하면서 철골부재의 제작 및 가공기술이 예전보다 더욱 향상되고 구조물로서의 품질관리에 대한 신뢰성의 요구도 증가되고 있는 실정이다, 그러나 국내의 철골조 건축부재의 구조설계는 설계사대로 각기 이루어지고 해당 부재는 공장별로 제작진행되어 그 기술수준에는 보이지 않는 상당한 격차가 있다고 보여지며 업체별로 경제성 등을 고려하여 기본적이며 일반적 철골제작기법을 간결하게 적용하는 것에 머물러 고도한 선진적인 기술의 채용은 대부분 주저할 수 밖에 없는 상황이다 또한, 중소규모의 빌딩 건축물들의 철골조 설계적용을 고려해볼 때 수많은 접합부의 표준화를 비롯하여 구조체 전체의 표준화 및 내$\cdot$외장재까지 포함된 시스템건축의 건축물설계와 부재의 제작 및 설치기술 개발경향도 엿보이고 있는 가운데 특히, 철골부재의 공장제작과 현장설치의 보다 경제적이고 짧은 공기내에 완전한 품질을 확보할 수 있는 부재간의 접합부 설계에 대한 연구검토는 철골분야에 종사하는 업계는 물론 현장 관계자에게도 의미있는 일일 것이다. 본 논문에서는 철골조 건축물의 특성을 알아보고 철골구조물 공장제작 및 현장설치공기를 최대한 단축할 수 있는 철골기둥과 기둥, 기둥과 큰보부재 접합부 변경사례 및 Box Column의 용접자동화, 로봇화에 의한 철골기둥 부재제작사례와 금후 철골구조물 제작상의 문제점과 대응방안에 대하여 서술하고자 한다.