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Brückendynamik : Winderregte Schwingungen von Seilbrücken
Citation Link: https://doi.org/10.15480/882.361
Publikationstyp
Book
Date Issued
1991
Sprache
German
Author(s)
Starossek, Uwe
Institut
TORE-DOI
Citation
Zugl.: Stuttgart, Univ., Diss., 1991 u.d.T.: Zum dynamischen Verhalten von Seilbrücken unter Windeinwirkung
ISBN
3-528-08881-8
The dynamic behavior of bridges is investigated, with special attention paid to the phenomenon of wind-induced flutter vibration and to the design family "cable-supported bridges". The aim is to understand the mechanisms of vibration, to verify and to improve known methods of calculation, to create new mechanical-mathematical tools where necessary and to make statements with regard to a dynamically advantageous design. The research method comprises comparative study of relevant publications, analytical and numerical calculation, and, based thereupon, clarifying discussion. Generally, small displacements are assumed (linear theory); calculations are effected in the frequency domain. Determination of aerodynamic forces proceeds from the assumption of plane instationary stream.
In the discussion of aerodynamic and aeroelastic basic relations, attention is focussed on the two-dimensional system. A review of the classical theory of flutter of a flat plate (aerofoil) is included, and a simplified arithmetical method for its execution is given. The applicability of the classical theory to bridges is investigated. An empirically modified theory of flutter makes use of measured aerodynamic coefficients (nonstationary derivatives). Available measuring methods are described and compared, and the applicability of the modified theory is investigated. Further discussion is dedicated to nonlinear aerodynamics and to dynamic-aeroelastic response behaviour.
Flutter calculation for more general systems, i.e. line-like three-dimensional systems, requires theoretical investigation of the aeroelastics of a beam with freedom to bend and twist. The approach by partial differential equations, as well as the finite-element concept, are applied. The latter leads to the development of two aeroelatic beam elements.
In order to account for the dynamic interaction between cables and other system elements (necessary for the calculation of composed systems), the dynamic stiffness matrix of a damped cable is derived. Its coefficients are analytical functions of the frequency of motion. They are subsequently represented by linear matrix polynomials, which facilitates the numerial solution of eigenvalue problems.
The acquired findings are applied to real bridge systems and, in particular, to cable-stayed bridges. In connection with the so-called system damping and alternatively proposed terms, a description of system inherent, dynamically advantageous mechanisms is given. By means of a numerical flutter study on a multi-cable system, the influence of non-affinity of mode shapes on the flutter behaviour is investigated.
In the discussion of aerodynamic and aeroelastic basic relations, attention is focussed on the two-dimensional system. A review of the classical theory of flutter of a flat plate (aerofoil) is included, and a simplified arithmetical method for its execution is given. The applicability of the classical theory to bridges is investigated. An empirically modified theory of flutter makes use of measured aerodynamic coefficients (nonstationary derivatives). Available measuring methods are described and compared, and the applicability of the modified theory is investigated. Further discussion is dedicated to nonlinear aerodynamics and to dynamic-aeroelastic response behaviour.
Flutter calculation for more general systems, i.e. line-like three-dimensional systems, requires theoretical investigation of the aeroelastics of a beam with freedom to bend and twist. The approach by partial differential equations, as well as the finite-element concept, are applied. The latter leads to the development of two aeroelatic beam elements.
In order to account for the dynamic interaction between cables and other system elements (necessary for the calculation of composed systems), the dynamic stiffness matrix of a damped cable is derived. Its coefficients are analytical functions of the frequency of motion. They are subsequently represented by linear matrix polynomials, which facilitates the numerial solution of eigenvalue problems.
The acquired findings are applied to real bridge systems and, in particular, to cable-stayed bridges. In connection with the so-called system damping and alternatively proposed terms, a description of system inherent, dynamically advantageous mechanisms is given. By means of a numerical flutter study on a multi-cable system, the influence of non-affinity of mode shapes on the flutter behaviour is investigated.
DDC Class
620: Ingenieurwissenschaften
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