The aim of this volume is to present to researchers and engineers working on problems concerned with the mechanics of solids and structures, the current state of the development and application to procedures for assessing the reliability of a system. Particular attention is paid to their use in the analysis of complex engineering systems. The topics covered reflect the need to integrate, within the overall methodology, statistical methods for dealing with uncertain parameters and random excitation with the development of a suitable safety indexes and design codes. The basic principles of reliability theory, together with current standard methodology, including a consideration of the operational, economic and legal aspects of reliability assurance, is reviewed, together with an introduction to new developments, such as the application of expert systems technology. Damage accumulation predictions, with applications in seismic engineering are also covered.
The aim of this volume is to present to researchers and engineers working on problems concerned with the mechanics of solids and structures, the current state of the development and application to procedures for assessing the reliability of a system. Particular attention is paid to their use in the analysis of complex engineering systems. The topics covered reflect the need to integrate, within the overall methodology, statistical methods for dealing with uncertain parameters and random excitation with the development of a suitable safety indexes and design codes. The basic principles of reliability theory, together with current standard methodology, including a consideration of the operational, economic and legal aspects of reliability assurance, is reviewed, together with an introduction to new developments, such as the application of expert systems technology. Damage accumulation predictions, with applications in seismic engineering are also covered.
The last decades have witnessed the development of methods for solving struc tural reliability problems, which emerged from the efforts of numerous re searchers all over the world. For the specific and most common problem of determining the probability of failure of a structural system in which the limit state function g( x) = 0 is only implicitly known, the proposed methods can be grouped into two main categories: • Methods based on the Taylor expansion of the performance function g(x) about the most likely failure point (the design point), which is determined in the solution process. These methods are known as FORM and SORM (First- and Second Order Reliability Methods, respectively). • Monte Carlo methods, which require repeated calls of the numerical (nor mally finite element) solver of the structural model using a random real ization of the basic variable set x each time. In the first category of methods only SORM can be considered of a wide applicability. However, it requires the knowledge of the first and second deriva tives of the performance function, whose calculation in several dimensions either implies a high computational effort when faced with finite difference techniques or special programs when using perturbation techniques, which nevertheless require the use of large matrices in their computations. In or der to simplify this task, use has been proposed of techniques that can be regarded as variants of the Response Surface Method.
Uncertainty is certain to be found in structural engineering, making it crucial to structure design. This book covers three competing philosophies behind structural safety and reliability: probabilistic analysis, fuzzy set-based treatments, and the convex approach. Explaining the theory behind probabilistic analysis, fuzzy set-based treatments, and the convex approach in detail, alongside their implementation, use, and benefits, the book compares and contrasts these methods, enabling the reader to solve problems associated with uncertainty. These uncertainty issues can be seen in civil engineering structures, risk of earthquakes, impact of rough seas on ships, and turbulence affecting aerospace vehicles. Building on the authors’ many years of experience in the field, Philosophies of Structural Safety and Reliability is an essential guide to structural uncertainty. Topics covered in the book include properties of materials and their structural deterioration, safety factor and reliability, risk evaluation and loads, and their combinations. This book will be of interest to students and professionals in the fields of aerospace, civil, mechanical, marine, and ocean engineering.
Have you ever wondered where the safety factors come from? Why is it that deterministic analysis has reached a very sophisticated level, but in the end empirical factors are still needed? Is there a way to select them, rather than assigning them arbitrarily as is often done? This book clearly shows that safety factors are closely related with the reliability of structures, giving yet another demonstration of Albert Einstein's maxim that "It is incomprehensible that Nature is comprehensible". The book shows that the safety factors are much more comprehensible if they are seen in a probabilistic context. Several definitions of the safety factors are given, analytical results on insightful numbers are presented, nonprobabilistic safety factors are shown, as well as their estimates derived by the inequalities of Bienayme, Markov, Chebushev and Camp-Meidell. A special chapter is devoted to important contributions by Japanese experts. This volume will help to critically re-think the issue of safety factors, which can create a false feeling of security. The deterministic paradigm can be enhanced by incorporating probabilistic concepts wisely where they are needed without treating all variables as probabilistic ones. The book shows that there is a need of their integration rather than separation. This book is intended for engineers, graduate students, lecturers and researchers.
A quarter of the century has elapsed since I gave my first course in structural reliability to graduate students at the University of Waterloo in Canada. Since that time on I have given many courses and seminars to students, researchers, designers, and site engineers interested in reliability. I also participated in and was responsible for numerous projects where reliability solutions were required. During that period, the scope of structural reliability gradually enlarged to become a substantial part of the general reliability theory. First, it is apparent that bearing structures should not be isolated objectives of interest, and, consequently, that constntCted facilities should be studied. Second, a new engineering branch has emerged -reliability engineering. These two facts have highlighted new aspects and asked for new approaches to the theory and applications. I always state in my lectures that the reliability theory is nothing more than mathematized engineering judgment. In fact, thanks mainly to probability and statistics, and also to computers, the empirical knowledge gained by Humankind's construction experience could have been transposed into a pattern of logic thinking, able to produce conclusions and to forecast the behavior of engineering entities. This manner of thinking has developed into an intricate network linked by certain rules, which, in a way, can be considered a type of reliability grammar. We can discern many grammatical concepts in the general structure of the reliability theory.
Smart (intelligent) structures have been the focus of a great deal of recent research interest. In this book, leading researchers report the state of the art and discuss new ideas, results and trends in 43 contributions, covering fundamental research issues, the role of intelligent monitoring in structural identification and damage assessment, the potential of automatic control systems in achieving a desired structural behaviour, and a number of practical issues in the analysis and design of smart structures in mechanical and civil engineering applications. Audience: A multidisciplinary reference for materials scientists and engineers in such areas as mechanical, civil, aeronautical, electrical, control, and computer engineering.
Les ponts en arc font actuellement face au double défi de protéger leur patrimoine et de rivaliser avec d'autres formes plus récentes de structures. La conservation des ponts en arc implique de multiples impératifs : une politique saine d'inspection et de suivi, des méthodes précises d'investigation, une évaluation fiable et un éventuel diagnostic, des moyens efficaces de maintenance, de réparation, de renforcement et d'élargissement. Pendant que des ouvrages existants sont réparés et revalorisés, de nouveaux ponts en arc, de -nies traditionnelles et à " l'échelle humaine ", continuent à se construire, en utilisant des matériaux et procédés améliorés et rentables, assurant longévité et respect de l'environnement. Au premier plan de cette continuité, les concepteurs des ponts en béton, dans les hémisphères Nord et Sud, s'efforcent avec succès de réaliser des portées en arc de plus en plus longues, frôlant les 400 mètres dans les années 1980. Récemment, sur d'autres sites spectaculaires, des records de portées ont été battus par trois ponts en arc respectivement en pierre, en béton, en tubes d'acier remplis de béton. Une telle avancée ne manquera pas d'inciter les ingénieurs à rechercher des formes d'arc encore plus audacieuses et élégantes. Sur le large éventail des thèmes proposés, de nombreux auteurs, de plus de vingt-cinq pays, ont apporté des contributions majeures rappelant que les ponts en arc n'ont rien perdu de leur actualité et que, malgré les leçons assimilées de leur prestigieux héritage, leur conception stimule toujours la créativité des ingénieurs et des architectes. Ces contributions sont réunies dans le présent volume édité à l'occasion de la Troisième Conférence internationale sur les Ponts en Arc, tenue à Paris en septembre 2001. Arch bridges face at present the double challenge of protecting their heritage and competing with other more recent structural forms. The conservation of the arch bridge heritage successively requires sound inspection and monitoring policies, accurate investigative methods, reliable assessment and eventual diagnosis, efficient means for maintenance, repair, strengthening and widening. While existing structures are being repaired and upgraded, new arch bridges, of traditional forms and on a "human scale", continue to be constructed, using improved and cost-effective materials and procedures, ensuring longevity and respect for the environment. In the forefront of this continuity, concrete bridge designers, in the northern and southern hemispheres, have successfully been striving for ever larger arch spans, closely approaching 400 m in the 1980's. Lately, at other spectacular sites, span records were beaten in three arch bridges respectively using stone, concrete and slender concrete-filled steel tubes. This breakthrough may encourage engineers to seek more daring and elegant forms of arch. On the broad spectrum of the suggested topics, numerous authors, from more than twenty-five countries, have recently offered major contributions, reminding that arch bridges have nothing lost of their appeal and that, for all the lessons learnt from their prestigious heritage, their design still simulates the creativity of engineers and architects. These contributions are put together in the present volume edited on the occasion of the Third International Arch Bridge Conference held in Paris in September 2001.
