Walter Lacarbonara Dipartimento di Ingegneria Strutturale e Geotecnica Università degli Studi di Roma "La Sapienza" Via Eudossiana, 18 - 00184 Roma e-mail: [email protected]
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Walter Lacarbonara
Dipartimento di Ingegneria Strutturale e GeotecnicaUniversità degli Studi di Roma "La Sapienza"
Via Eudossiana, 18 - 00184 Roma
e-mail: [email protected]
Tacoma Narrows Bridge
Tacoma Narrows, USA, 11.1940 U=18.6 m/s
Volgograd Bridge
Volgograd, Russia, 20.5.2010 U=18 m/s
Aeroelastic phenomena
Aerodynamic wind loads
Loss of stability: divergence or Hopf
Outline
•
Suspension bridges
l = 888 m
l = 1490 m
Nonlinear model of suspension bridges
Nonlinear model of suspension bridges
1.
2.
3.
Nonlinear model of suspension bridges
Nonlinear model of suspension bridges
Nonlinear model of suspension bridges
Nonlinear model of suspension bridges
Discretization (PDE mode)
Suspension bridges: equilibrium paths
Suspension bridges: torsional divergence
Suspension bridges: torsional divergence
Ponte della Musica
Ponte della Musica
Ponte della Musica
Arch bridges: kinematics
Arch bridges: kinematics
Arch bridges: Equations of motion
Ponte della Musica: softening behavior
÷
Ponte della Musica: modal properties
Ponte della Musica: frequencies
Ponte della Musica: flutter
Ponte della Musica: flutter
Ponte della Musica: flutter
Ponte della Musica: flutter mode
Ponte della Musica: sensitivity analyses
Ponte della Musica: sensitivity analyses
On-going work: indicial functions theory
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Indicial functions theory
Linear theory
o Aerodynamic coefficients linearized with respect to the state
variables if their variations are smooth functions of those
states.
o The linear step-change response can be convoluted with the
input to predict the output of a linear system, the nonlinear
indicial theory is a generalization of this concept.
Nonlinear theory
o Linear formalism in the form of a generalized superposition
integral, states evolution depends on the entire history of the
motion.
o The aeroelastic response to an arbitrary input can be
constructed by integrating a nonlinear functional, that
involves the knowledge of the time-dependent input and the
indicial response.
Indicial functions theory
Linear/nonlinear indicial functions
CFD calculations
U wind upstream 8m/s ; Re = 1.65 107
Wide range of CFD
results in literature
Unsteady aerodynamics lag states
Numerical approaches
Summary
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Solar tracker: flutter and passive control
Rome, December, 2009
U=23.65 m/s
Acknowledgments
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