Flutter vulnerability assessment of flexible bridges [Elektronische Ressource] / by Claudio Mannini

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• Publié par: technische_universitat_carolo-wilhelmina_zu_braunschweig
• Publié le: 01 janvier 2007
• Nombre de lectures: 14
• Langue: English
• Poids de l'ouvrage: 11 Mo

Extrait

Flutter Vulnerability Assessment
of Flexible Bridges
Dissertation
submitted to, and approved by,
the Department of Architecture, Civil Engineering and Environmental Sciences
of the Technische Universit˜at
Carolo-Wilhelmina
zu Braunschweig
and
the Faculty of Engineering
Department of Civil
of the University of Florence
in candidacy for the degree of a
Doktor-Ingenieur (Dr.-Ing.)/
Dottore di Ricerca in Risk Management on the Built Environment*)
by
Claudio Mannini
from Florence, Italy
Submitted on 31 March 2006
Oral examination on 19 May 2006
Professoral advisor Prof. Udo Peil
Prof. Gianni Bartoli
2006
*) Either the German or the Italian form of the title may be used.The dissertation is published in an electronic form by the Braunschweig university
library at the address
http://www.biblio.tu-bs.de/ediss/data/Tutors
Prof. Dr.-Ing. Gianni Bartoli University of Florence Udo Peil Technical University of Braunschweig
Doctoral course coordinators
Prof. Dr.-Ing. Claudio Borri University of Florence Udo Peil Technical University of Braunschweig
Examining Committee
Prof. Dr.-Ing. Gianni Bartoli University of Florence Reinhard Leithner Technical University of Braunschweig
Prof. Dr. Giorgia Giovannetti University of Florence
Prof. Dr.-Ing. Herald Budelmann Technical University of Braunschweig Claudio Borri University of Florence
Prof. Dr.-Ing. Hocine Oumeraci Technical University of Braunschweig Enrica Caporali University of Florence
Prof. Dr.-Ing. Udo Peil Technical University of Braunschweig Marcello Ciampoli University of Rome \La Sapienza"
Prof. Dr. rer. nat. Heinz Antes Technical University of Braunschweig Dr.-Ing. Andrea Vignoli University of Florence
Prof. J˜orn Pachl Technical University of Braunschweig Dr.-Ing. Renzo Ciu– University of Florence
Prof. Joachim Stahlmann Technical University of BraunschweigThis thesis is dedicated to my familyAbstract
Risk management is a modern concept concerning the way to cope with natural and
maninduced catastrophic events. Deflnitions of risk are reported and discussed and the particular
relevance of Aeolian risk for a built environment is highlighted. Due to their strategic and
neuralgicrole, theimportanceofbridgestructuresas\elementsatrisk" isclear. Itisalsowell
known that uid-structure interaction (aeroelasticity) can give rise to phenomena of major
concernforthedesignof exiblebridges. Inparticular uttercaninducedivergingoscillations
and consequently bring to the collapse of the structure. This doctoral work focuses on the
vulnerability assessment of exible bridges with respect to utter and two main contributions
can be remarked.
First, the Performance-Based Design approach is applied to the collapse limit state due to
utter, following the Paciflc Earthquake Engineering Research Center (PEER) formulation.
This risk-consistent design philosophy has been developed in the seismic engineering fleld and
only recently some attempts have been made to adapt it to wind applications
but never taking into account aeroelastic phenomena. For the flrst time utter derivatives
are considered as random variables and the utter problem is approached in a probabilistic
way via Monte-Carlo simulations. A single-box girder deck is experimentally studied in the
CRIACIV wind tunnel in order to make available data for this particular analysis. Interesting
results are obtained both for this section model and for two rectangular cylinders.
The second main contribution of this work is a sort of \pre-normative"study concerning
utter assessment, which could be useful to enhance the codes, as a measure of risk
mitigation. The flnal goal is the set-up of a simplifled method to estimate the utter critical wind
speed without performing wind-tunnel tests. Such a tool could be very useful for bridge
engineers, especially concerning medium-span exible bridges and/or pre-design stages. As a
matter of fact, deep wind-tunnel investigations are expensive and time-consuming and, albeit
absolutely necessary over all the design steps for long-span suspension bridges, they could be
sometimes avoided or limited to the flnal validation stage for less important structures, for
which aeroelastic phenomena are less concerning, even though they cannot be excluded a
priori. In this context, the relationship between multimodal and bimodal approach to utter is
carefully analyzed and discussed, also with the support of two case studies, and then
approximateformulasretainingonlythreeaeroelasticfunctionsarederived. Thisstrongsimpliflcation
is validated on the basis of a wide range of structural and aerodynamic data, showing its
extensive applicability. Finally, a relatively large number of utter derivative sets are compared
accordingtothedeflnitionofafewclassesofdeckcross-sectionalgeometry. Thesedatainclude
the trapezoidal single-box deck section with lateral cantilevers, whose experimental tests in
the CRIACIV wind tunnel are described in details. The previously mentioned simplifled
formulas, reducing to three the utter derivatives to be accounted for, make possible an attempt
of generalization. Although this is only a flrst step towards this ambitious goal, it shows all
the di–culties which have to be overcome but also highlights some interesting and promising
results.
viiAcknowledgements
First of all I would like to thank my tutors, Prof. Gianni Bartoli and Prof. Udo Peil, for their
support and advice. I feel particularly grateful to Prof. Gianni Bartoli for the enthusiasm
for scientiflc research that he has always transmitted to me, as well as for the continuous
supervision of the progress of my work. A special thanks to Prof. Claudio Borri for the strong
support and encouragement he has given me during the entire period of study and to Prof.
Francesco Ricciardelli, who extensively reviewed this dissertation, for his useful remarks and
suggestions. All my gratitude to Lorenzo Procino for his constant and indispensable help
during the long wind-tunnel test campaign and to Serena Cartei who has friendly supported
me in all the bureaucratic issues. I sincerely also have to thank all the colleagues of the
International Doctoral Course for the help I have often received during these three years and
for their friendly companionship. Then a special thanks to Carlotta Costa, Stefano Past o and
Luca Salvatori for the extremely fruitful scientiflc discussions and exchange of ideas.
A grateful acknowledgement to CSTB-Nantes, and in particular to Olivier Flamand and
G¶erard Grillaud, for the large quantity of data they made available for this research work. It
is also impossible to forget the warm welcome I received at DLR-G˜ottingen and the precious
scientiflcenrichmentIgotmeetingDr. Gun˜ terSchewe,Dr. RalphVo…andAnteSoda. Finally
I would like to thank Prof. Masaru Matsumoto and Prof. Partha Sarkar for the data they
kindly sent me.
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