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D_Trein_Cristiano_Augusto.pdfDissertation_全文24.12 MBAdobe PDF見る/開く
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タイトル: Study on the Unsteady Pressure Characteristics of Bluff Bodies focusing on Flutter Stabilization of Long-Span Bridges
その他のタイトル: 長大橋のフラッター安定化に着目した非流線型物体の非定常圧力特性に関する研究
著者: Cristiano Augusto Trein
キーワード: 長大橋
フラッター
非定常圧力
非定常空気力
耐風安定性
発行日: 24-Sep-2009
出版者: Kyoto University
抄録: With the increase of the spans in the last decades, new concepts of projects and perceptions about bridges around the world have imposed the need of the development of new design techniques. Aerodynamic instabilities, which were not being of concern not long time ago, started to demand special care during all phases of the projects. Among them, coupledflutter instability has gained remarkable importance, due to its catastrophic consequences and impacts on the safety of the structure. Concerning coupled-flutter, aerodynamic derivatives have been regarded as fundamental components for the assessment of the stability of long-span bridges, resulting in that the focus during the proposition of the bridge deck geometry has been put essentially on the control of those empirical indices. The relationships between bridge deck geometric characteristics and the values assumed by those indices are recognized to be non-linear and straightforward approaches for their prompt evaluation are still not available. Because of that, trial and error experimental techniques based on wind tunnel tests have been regarded as main tools in the search of geometric configurations of bridge decks that satisfy the flutter stability requirements from the aerodynamic derivatives point of view. Since aerodynamic derivatives are resultant from the unsteady pressure characteristics developed along the bridge deck, it must be more rational to search for relationships between deck geometry and flutter stabilization from the unsteady pressure characteristics point of view. However, the complex geometric characteristics associated to modern longspan bridges may impose difficulties on the pressure measurements in wind tunnel tests, becoming counter-productive. So, the direct evaluation of the aerodynamic derivatives through alternative methods has been preferred in wind tunnel tests. In this research, the impacts of the deck geometric characteristics on the aerodynamic derivatives and, consequently, on flutter stabilization are assessed from the unsteady pressure characteristics point of view. Rectangular cross-sections arranged in single box and twobox configurations are used as base geometries and the influences of different geometric singularities (geometric modifications as leading edges, vertical plates and slots) on the unsteady pressure characteristics of those cylinders are systematized through the proposition of semi-empirical formulations. The knowledge generated herein may serve as a base for the development of a design framework based on the direct manipulation of the unsteady pressure characteristics of the deck through the use of geometric singularities, aiming the flutter stabilization by controlling indirectly the aerodynamic derivatives. Such a framework is to be used in substitution of some stages of wind tunnel test campaigns, and its feasibility is evaluated along the study. It was concluded that the relationships of geometric singularities with the unsteady pressure characteristics are much more linear and predictable than their relationships with the aerodynamic derivatives, opening a new methodology for the proposition of geometric improvements. Data regarding the geometries studied herein are also provided along the study, as reference for future development.
学位授与大学: Kyoto University (京都大学)
学位の種類: 新制・課程博士
取得分野: 博士(工学)
報告番号: 甲第14914号
学位記番号: 工博第3141号
請求記号: 新制/工/1471
整理番号: 27352
研究科・専攻: 京都大学大学院工学研究科社会基盤工学専攻
論文調査委員: (主査)教授 白土 博通, 教授 杉浦 邦征, 教授 河井 宏允
学位授与の要件: 学位規則第4条第1項該当
著作権等: 許諾条件により本文は2010-03-01に公開
DOI: 10.14989/doctor.k14914
URI: http://hdl.handle.net/2433/85380
出現コレクション:博士(工学)

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