Structural And System Reliability

Offers a modern, rigorous and comprehensive treatment of the subject using numerous well-designed examples and end-of-chapter problems.

Structural reliability theory is concerned with the rational treatment of uncertainties in struc tural engineering and with the methods for assessing the safety and serviceability of civil en gineering and other structures. It is a subject which has grown rapidly during the last decade and has evolved from being a topic for academic research to a set of well-developed or develop ing methodologies with a wide range of practical applications. Uncertainties exist in most areas of civil and structural engineeri'1.g and rational design decisions cannot be made without modelling them and taking them into account. Many structural en gineers are shielded from having to think about such problems, at least when designing simple structures, because of the prescriptive and essentially deterministic nature of most codes of practice. This is an undesirable situation. Most loads and other structural design parameters are rarely known with certainty and should be regarded as random variables or stochastic processes, even if in design calculations they are eventually treated as deterministic. Some problems such as the analysis of load combinations cannot even be formulated without recourse to probabilistic reasoning.

Publisher Description

This volume contains 28 papers by renowned international experts on the latest advances in structural reliability methods and applications, engineering risk analysis and decision making, new optimization techniques and various applications in civil engineering. Moreover, several contributions focus on the assessment and optimization of existing str

This book provides readers with an understanding of the fundamentals and applications of structural reliability, stochastic finite element method, reliability analysis via stochastic expansion, and optimization under uncertainty. It examines the use of stochastic expansions, including polynomial chaos expansion and Karhunen-Loeve expansion for the reliability analysis of practical engineering problems.

During the last two decades more and more universities offer courses on modern structural reliability theory. A course on structural reliability theory is now a natural part of the curri culum for mechanical and structural engineering students. As a result of this, a number of textbooks have been published in this decade. In PlOst of these books it is shown how the reliability of single structural members can be evaluated in a rational way. The methods used are usually so-called level 2 methods, i. e. methods involving certain approximate iter ative calculations to obtain an approximate value of the probability of failure of the struc tural members. In these methods the joint probability distribution of relevant variables (re sistance variables, loads, etc. ) is simplified and the failure criteria are idealized in such a way that the reliability calculations can be performed without an unreasonable amount of work. In spite of the approximations and idealizations made it is believed that a rational treatment of uncertainties in structural engineering can be obtained by level 2 methods. Usually, in sufficient data are at hand to make a more advanced estimate of the reliability of a struc tural member. It has been recognized for many years that a fully satisfactory estimate of the reliability of a structure must be based on a systems approach. In some situations it is sufficient to estimate the reliability of the individual structural members of a structural system.

This volume contains 28 papers by renowned international experts on the latest advances in structural reliability methods and applications, engineering risk analysis and decision making, new optimization techniques and various applications in civil engineering. Moreover, several contributions focus on the assessment and optimization of existing structural systems. All contributions were presented at the 15th Working Conference of the International Federation of Information Processing (IFIP) Working Group 7.5 on Reliability and Optimization of Structural Systems, held at the Oskar von Miller Forum in Munich, Germany, April 2010. Working Group 7.5’s purposes are to promote modern structural system reliability and optimization theory and its applications, to stimulate research, development and application of structural system reliability and optimization theory, to assist and advance research and development in these fields, to further the dissemination and exchange of information on reliability and optimization of structural systems, and to encourage education in structural system reliability and optimization theory. This volume is intended for structural and mechanical engineers working and researching in structural optimization and risk/reliability analysis, applied to structural and infrastructural systems.

This book addresses probabilistic methods for the evaluation of structural reliability, including the theoretical basis of these methods. Partial safety factor codes under current practice are briefly introduced and discussed. A probabilistic code format for obtaining a formal reliability evaluation system that catches the most essential features of the nature of the uncertainties and their interplay is then gradually developed. The concepts presented are illustrated by numerous examples throughout the text. The modular approach of the book allows the reader to navigate through the different stages of the methods.

Reliability of Structures enables both students and practising engineers to appreciate how to value and handle reliability as an important dimension of structural design. It discusses the concepts of limit states and limit state functions, and presents methodologies for calculating reliability indices and calibrating partial safety factors. It also supplies information on the probability distributions and parameters used to characterize both applied loads and member resistances. This revised and extended second edition contains more discussions of US and international codes and the issues underlying their development. There is significant revision and expansion of the discussion on Monte Carlo simulation, along with more examples. The book serves as a textbook for a one-semester course for advanced undergraduates or graduate students, or as a reference and guide to consulting structural engineers. Its emphasis is on the practical applications of structural reliability theory rather than the theory itself. Consequently, probability theory is treated as a tool, and enough is given to show the novice reader how to calculate reliability. Some background in structural engineering and structural mechanics is assumed. A solutions manual is available upon qualifying course adoption.

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.