vibration control with shape-memory alloys

300 Pages·2011·9.31 MB·English

VIBRATION CONTROL WITH
SHAPE-MEMORY ALLOYS
IN CIVIL ENGINEERING STRUCTURES
Filipe Pimentel Amarante dos Santos
Mestre em Engenharia de Estruturas
Dissertac¸a˜o apresentada `a Faculdade de Ciˆencias e
Tecnologia da Universidade Nova de Lisboa para obtenc¸a˜o
do grau de Doutor em Engenharia Civil
Orientador: Professor Doutor Corneliu Cisma¸siu
Ju´ri:
Presidente: Professor Doutor Manuel Am´erico Gonc¸alves da Silva
´
Arguente: Professor Doutor Alvaro Alberto de Matos Ferreira da Cunha
Arguente: Professor Doutor Lu´ıs Manuel Coelho Guerreiro
Vogal: Professor Doutor Anto´nio Jos´e Lu´ıs dos Reis
Vogal: Professor Doutor Jo˜ao Carlos Gomes Rocha de Almeida
Marc¸o 2011

“Copyright” Filipe Pimentel Amarante dos Santos, FCT/UNL e UNL
AFaculdadedeCiˆencias eTecnologia eaUniversidade Nova deLisboatˆem odireito,
perp´etuo e sem limites geogr´aficos, de arquivar e publicar esta disserta¸c˜ao atrav´es
de exemplares impressos reproduzidos em papel ou de forma digital, ou por qual-
quer outro meio conhecido ou que venha a ser inventado, e de a divulgar atrav´es de
reposito´rios cient´ıficos e de admitir a sua c´opia e distribuic¸˜ao com objectivos edu-
cacionais ou de investiga¸c˜ao, n˜ao comerciais, desde que seja dado cr´edito ao autor e
editor.

To my wife Inˆes and our son Afonso

Acknowledgments
This dissertation would not have been accomplished without the support and assis-
tance from many people in many different ways.
I would like to express my deepest and heartfelt recognition to my adviser, Prof.
Corneliu Cisma¸siu. I cannot thank him enough for his priceless scientific teachings,
for his invaluable guidance and commitment, for his inestimable encouragement,
confidence and utmost support, and last but not the least, for his enormous gen-
erosity and kind friendship, which have made this graduation experience so positive
and so meaningful. To work with him was a great pleasure and a privilege.
I am truly and forever grateful to Prof. J. Pamies Teixeira for his incalculable help
during the design and construction phases of the physical prototype. Without his
inspired input and thoughtful dedication the interdisciplinary nature of this study
could not have been achieved.
I would like to show my true appreciation to Prof. F. M. Bra´s Fernandes, who first
brought me into the shape-memory world and with whom I had so many fruitful
and delightful discussions, and to K.K. Mahesh for his precious help during the DSC
tests.
I would like to thank Prof. Fernando Coito for his availability and for his insightful
explanations about modern control engineering.
I am also indebted to Prof. J. C. G. Rocha de Almeida and I profoundly thank him
for his unconditional support in overcoming all the bureaucratic perils that have
appeared along the way.
I thank Prof. M. Gon¸calves da Silva for his warm welcome to the Civil Enginnering
Department and for his relentless efforts in providing me with the necessary logistic
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conditions to pursuit this work.
I kindly acknowledge Prof. F. Henriques for the use of the infrared camera, during
the study of the transformation fronts.
I thank Prof. Ant´onio Reis for introducing me to scientific investigation, for inciting
my natural curiosity in the pursuit of further knowledge and for motivating me to
continue my academic studies. I am also grateful to him for the technical data
regarding the S. Martinho viaduct.
To my colleagues and friends I thank for all the good disposition and support.
I specially would like to thank my good friend M´ario Silva for his priceless technical
support with Linux, always managing to solve the innumerable helpless situations I
foundmyself into during thecoarseofthis work. Ialso thankhimandJos´eVarandas
for all the waves I had the pleasure of sharing with them and for all the laughter.
I thank my parents for all their love and everlasting devotion.
Finally, all my love goes to Inˆes and Afonso as they are the bright sunshine of my
life.
I acknowledge the financial support of Fundac¸˜ao Calouste Gulbenkian (bolsa de
curta dura¸c˜ao) and of Fundac¸˜ao para a Ciˆencia e Tecnologia (FCT/MCTES grant
SFRH/BD/37653/2007).
Abstract
The superelastic behavior exhibited by shape-memory alloys shows a vast potential
for technological applications in the field of seismic hazard mitigation, for civil engi-
neering structures. Due to this property, the material is able to totally recover from
large cyclic deformations, while developing a hysteretic loop. This is translated into
a high inherent damping, combined with repeatable re-centering capabilities, two
fundamental features of vibration control devices.
Anextensive experimental programprovidesavaluableinsightintotheidentification
of the main variables influencing superelastic damping in Nitinol while exploring the
feasibility and optimal behavior of SMAs when used in seismic vibration control.
The knowledge yielded from the experimental program, together with an extensive
bibliographic research, allows for the development of an efficient numerical frame-
work for the mathematical modeling of the complex thermo-mechanical behavior of
SMAs. These models couple the mechanical and kinetic transformation constitutive
laws with a heat balance equation describing the convective heat problem. The seis-
mic behavior of a superelastic restraining bridge system is successfully simulated,
being one of the most promising applications regarding the use of SMAs in civil
engineering structures.
A small-scale physical prototype of a novel superelastic restraining device is built.
The device is able to dissipate a considerable amount of energy, while minimizing
a set of adverse effects, related with cyclic loading and aging effects, that hinder
the dynamic performances of vibration control devices based on passive superelastic
wires.
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