Bridge Aerodynamic Stability Civil Engineering

114 Pages·2014·2.39 MB·English

Bridge Aerodynamic Stability
Instability Phenomena and Simplified Models

André Miguel da Silva Rebelo de Campos

Dissertation for the degree of Master of Science
Civil Engineering

President: Professor Luís Manuel Coelho Guerreiro
Internal examiner: Professor Pedro António Martins Mendes
Supervisor: Professor António José Luís dos Reis

NOVEMBER 2014
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Abstract
With the collapse of the Tacoma Narrows Bridge a new area of study was born within the branch of
Civil Engineering. This area, called Aeroelasticity, considers the effects of a bridge deck immerse in a
wind flow. This has become more and more important due to the ever increasing length of spans in
cable supported bridges.
Even though this is a new subject within Civil Engineering, Aeroelasticity had already been studied for
some time by the Aeronautical Industry. Because of this, most theories applied nowadays to deck
cross sections have been adapted from aerofoils and flat plates’ behaviour.
Aeroelasticity provides answers for what kind of displacements and forces occur when a bridge deck
is subjected to a flow of air. It also defines what instability phenomena can occur in this situation.
Furthermore, experimental procedures and simplified models have been developed to help with the
evaluation of the stability of bridge decks. These are presented in this dissertation and are applied to
practical cases to evaluate their validity.

Keywords:
Aeroelasticity, Instability Phenomena, Wind Tunnel Testing, Approximated Formulas, Bidimensional
Models

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Resumo
Com o colapso da ponte de Tacoma Narrows, surgiu, na Engenharia Civil, uma nova area de estudo
chamada Aeroelasticidade. Esta área considera os efeitos provocados num tabuleiro de uma ponte
imerso num escoamento de vento. Estes fenómenos são cada vez mais importantes devido ao
comprimento cada vez maior dos vãos de pontes suspensas e atirantadas.
Apesar de ser uma nova disciplina na área da Engenharia Civil, a Aeroelasticidade já era objecto de
estudo da Industria Aeronautica há algum tempo. Isto traduziu-se na adaptação das teorias usadas
para prever o comportamento de “aerofólios” e placas finas para os tabuleiros das pontes.
A aeroelasticidade explica quais os movimentos e forças que surgem nestes tabuleiros quando são
sujeitos a um escoamento de vento. Também identifica quais os fenómenos de instabilidade passiveis
de ocorrer.
Além disso, existem procedimentos experimentais e modelos simplificados que têm sido
desenvolvidos de modo a verificar a estabilidade deste tipo de estruturas. Neste relatório, estes são
apresentados e aplicados a casos práticos para avaliar a sua validade.

Palavras-chave:
Aeroelasticidade, Fenómenos de Instabilidade, Ensaios em Túneis de Vento, Formulas Aproximadas,
Modelos Bidimensionais

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Acknowledgements
To professor António José Luís dos Reis, for his availability and readiness in providing references as
well as help with any obstacle that crossed the way.
To my friends, whose support I couldn’t have done without.
To my parents, for their unconditional support and for all the help and care they provided.
To my brother and sister, for all the help and stress relief moments.
And especially to my friend Ana Raquel Crespo, for her love and all the hours spent supporting me no
matter what.

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