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CONTENTS
Volume 3, Number 4, December 2000
 

Abstract
Structural dynamics usually applies modal transformation rules aimed at de-coupling and/orrnminimizing the equations of motion. Proper orthogonal decomposition provides mathematical andrnconceptual tools to define suitable transformed spaces where a multi-variate and/or multi-dimensionalrnrandom process is represented as a linear combination of one-variate and one-dimensional uncorrelatedrnprocesses. Double modal transformation is the joint application of modal analysis and proper orthogonalrndecomposition applied to the loading process. By adopting this method the structural response is expressed as arndouble series expansion in which structural and loading mode contributions are superimposed. Thernsimultaneous use of the structural modal truncation, the loading modal truncation and the cross-modalrnorthogonality property leads to efficient solutions that take into account only a few structural and loadingrnmodes. In addition the physical mechanisms of the dynamic response are clarified and interpreted.

Key Words
double modal transformation; modal analysis; proper orthogonal decomposition; structural dynamics; wind engineering.

Address
Giovanni Solari and Luigi Carassale, DISEG, Department of Structural and Geotechnical Engineering, University of Genova, Via Montallegro, 1-16145 Genova, Italy

Abstract
To develop galloping suppression devices, it is important to understand the effects of windrnturbulence on galloping and to establish an evaluation method which takes

Key Words
galloping; overhead transmission lines; wind turbulence; numerical simulation.

Address
Takeshi Ohkuma, Department of Architecture, Kanagawa University, 3-27-1 Rokkaku-bashi, Kanagawa-ku, Yokohama 221-0802, JapanrnHisao Marukawa, Urban Environment Research Center, Izumi Sohken Engineering Co., Ltd. 51 Minami-sode, Sodegaura, Chiba 299-0268, Japan

Abstract
Wind-induced interference effects on a building are the result of one or more adjacentrnbuildings modifying the flow of wind around it, which may result in a significant increase or decrease inrnwind loads on the building. Wind loading standards and codes of practice offer little guidance to therndesigner for assessing the effects of interference. Experimental results on interference effects indicate thatrncode recommendations may be significantly low (unsafe) or uneconomically conservative. The paper presentsrnresults of an extensive experimental program to study the wind flow mechanisms and to quantify thernextent of wind load modifications on buildings due to interference effects. These results have beenrnsimplified and presented from the point-of-view of design and codification for the case of two buildings.rnBased on these results, general guidelines and limiting conditions defining wind interference are formulatedrnand discussed.

Key Words
buildings; design; interference effects; shielding; wind loads; wind tunnel experiments.

Address
Atul C. Khanduri, Risk Management Solutions Inc., 149 Commonwealth Drive, Menlo Park, CA 94025, USArnTheodore Stathopoulos and Claude Bedard, Centre for Building Studies, Concordia University, 1455 de Maisonneuve West, Montreal H3G 1M8, Canada

Abstract
This paper aims to describe the aerodynamic vibrations of various structural elements ofrnbridges, which are particular issues at present. The aerodynamic countermeasures for those vibrations arernalso discussed considering the generation mechanisms of the aerodynamic instabilities. In this paper, anrnexample of vortex-induced oscillation of bridge deck and its lesson are discussed. Next, the wind-inducedrncable vibration and its aerodynamic countermeasures are reviewed. Then, the aerodynamic characteristicsrnon two edge girders and their feasibility for application to long span cable-stayed bridges are considered.rnFurthermore, the bridge decks for future long span bridges are proposed and their aerodynamic characteristicsrnare also discussed.

Key Words
bridge aerodynamics; vortex-induced vibration; cable vibration; flutter; two-edge girders; super long span bridges.

Address
Masaru Matsumoto, Hiromichi Shirato, Tomomi Yagi, Department of Global Environment Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501, Japan

Abstract
The main purpose of this paper is to demonstrate the necessity of considering wind loadrncombinations even for low-rise buildings. It first discusses the overall quasi-static wind load effects andrntheir combinations to be considered in structural design of low-rise buildings. It was found that the maximumrntorsional moment closely correlates with the maximum along-wind base shear. It was also found that therninstantaneous pressure distribution causing the maximum along-wind base shear was quite similar to thatrncausing the maximum torsional moment, and that this asymmetric pressure pattern simultaneously accompaniesrnconsiderable across-wind and torsional components. Secondly, the actual wind pressure distributions causingrnmaximum quasi-static internal forces in the structural frames are conditionally sampled and their typical pressurernpatterns are presented.

Key Words
wind load combination; low-rise buildings; quasi-static wind load; pressure distrubution; along-wind base shear; across-wind base shear; torsional moment.

Address
Yukio Tamura, Department of Architectural Engineering, TIP, 1583 Iiyama, Astugi, JapanrnHirotoshi Kikuchi and Kazuki Hibi, RIT, Shimizu Corporation, Etchujima 3-4-17, Koto-ku, Tokyo, Japan

Abstract
A new finite element technique to solve the problem of wind and structure interactions isrnpresented. Conventionally, wind analysis is performed on the Eulerian description in which the finiternelement mesh would not move in accordance with the wind flow. However, it is not the case in wind-structurerninteraction problems because nodes attached to the surface of structure should move with therndisplacement of structure. The arbitrary Lagrangian-Eulerian (ALE) method treats the mesh and flowrnindependently, and allow the mesh to move. In this study, the analysis domain is divided into regions ofrnthe structure, air around the structure and the interface of two regions. To satisfy the compatibility andrnequilibrium conditions between separated regions and to carry out the efficient analysis, the rigid link isrnused. Also the equation of wind and that of structure are arranged in a single matrix equation.

Key Words
 

Address
Chang-Koon Choi and Won-Jin Yu, Department of Civil Engineering, KAIST, Taejon 305-701, Korea


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