• Wind and Structures
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• 제13권4호
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• pp.327-346
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• 2010

During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on the assessment of the dynamic behaviour of the line conductors under downburst loading. A non-linear numerical model, accounting for large deformations and the effect of pretension loading, is developed and used to predict the natural frequencies and mode shapes of conductors at various loading stages. A turbulence signal is extracted from a set of full-scale data. It is added to the mean component of the downburst wind field previously evaluated from a CFD analysis. Dynamic analysis is performed using various downburst configurations. The study reveals that the response is affected by the background component, while the resonant component turns to be negligible due large aerodynamic damping of the conductors.

• Wind and Structures
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• 제14권5호
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• pp.481-498
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• 2011

During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on assessing the behaviour of self supported transmission line towers under downburst loading. A parametric study is performed to determine the critical downburst configurations causing maximum axial forces for various members of a tower. The sensitivity of the internal forces developing in the tower's members to changes in the downburst size and location was studied. The structural behaviour associated with the critical downburst configurations is described and compared to the behaviour under 'normal' wind loads.

• 한국항행학회논문지
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• 제14권6호
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• pp.975-983
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• 2010

본 논문에서는 하노이의 탑 (Tower of Hanoi; ToH) 문제를 확장한 문제들을 소개하고, ToH 문제의 상태 공간을 그래프로 표현하기 위한 새로운 방안을 제시하고자 한다. 확장한 문제들로는 기둥의 수를 늘린 경우, 디스크 스택의 수를 늘린 경우, 그리고 일반 상태 간의 이동에 대한 세 가지를 소개하고, 다른 변종 문제들을 소개하고자 한다. 우리가 본 논문에서 제시한 새로운 표현 방안은 기존의 하노이 그래프 표현에 대해 확장된 방식의 그래프 표현을 제시하는 것이다. 제안된 표현에서는 각 디스크마다 하나의 직교좌표를 부여해 줌으로써 링크의 표시와 상태의 변화가 디스크가 어느 기둥에 배치되어 있는가와 시각적으로 일치된 시각화를 가능하게 해 준다. 제안된 표현을 기존의 하노이 그래프와 비교해 보면, 제안된 표현에서 디스크를 옮길 수 없는 링크를 제거하면 기존의 하노이 그래프와 isomorphic하다. 따라서, 제안된 표현은 기존의 하노이 그래프를 확장하여 표현력을 고도화한 것임을 알 수 있다. 제안된 표현에 대한 독자들의 이해를 돕기 위해, 우리는 본 논문에서 디스크의 개수가 2와 3인 경우에 대한 제안된 표현의 시각화 예를 제시하였다.

• Steel and Composite Structures
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• 제3권2호
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• pp.141-152
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• 2003

The ski jump in Innsbruck known for the famous annual New Year "Four-ski-jump-tournament" has been fully renewed. The original jumping tower (built for the 1976 Olympic winter games) was fully pulled down and a new landmark similar to a lighthouse has been erected located on a small hill at the border of the city. Zaha Hadid(London) won the international architectural competition for this significant building. The constructional realisation has been ordered from Aste Konstruktion and has been finally honoured with the Austrian state award for consulting 2002. After a very strict timetable the building was already handed restaurant at the top.

• Wind and Structures
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• 제25권1호
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• pp.79-100
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• 2017

The use of wind energy resources is developing rapidly in recent decades. There is an increasing number of wind farms in high wind-velocity areas such as the Pacific Rim regions. Wind turbine towers are vulnerable to tropical cyclones and tower failures have been reported in an increasing number in these regions. Existing post-disaster failure case studies were mostly performed through forensic investigations and there are few numerical studies that address the collapse mode simulation of wind turbine towers under strong wind loads. In this paper, the wind-induced failure analysis of a conventional 65 m hub high 1.5-MW wind turbine was carried out by means of nonlinear response time-history analyses in a detailed finite element model of the structure. The wind loading was generated based on the wind field parameters adapted from the cyclone boundary layer flow. The analysis results indicate that this particular tower fails due to the formation of a full-section plastic hinge at locations that are consistent with those reported from field investigations, which suggests the validity of the proposed numerical analysis in the assessment of the performance of wind-farms under cyclonic winds. Furthermore, the numerical simulation allows to distinguish different failure stages before the dynamic collapse occurs in the proposed wind turbine tower, opening the door to future research on the control of these intermediate collapse phases.

• 국제초고층학회논문집
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• 제5권4호
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• pp.293-304
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• 2016

The diagrid structural system for constructing tall buildings is a recent invention. Debuting in 2004 with the construction of the Swiss Re Tower in London, this aesthetically driven structural system has centered the perfecting of its technology on the development of the nodes that form its innovative deviation from standard steel tall framing methods. The paper examines variations in node design, understanding the linked dependence the modularity and the choice to expose the steel in the building, as well as on advances in digital modelling that allow an increasingly seamless line of communication from the engineering design through to the actual fabrication of the nodes. This advanced design and fabrication technology will be seen to have resulted in the expanded use of the technical term "node" to inform the design and construction of a range of other applications in the structuring of tall buildings, including the use of steel castings.