Progressive building collapse occurs when failure of a structural component leads to the failure and collapse of surrounding members, possibly promoting additional collapse. Global system collapse will occur if the damaged system is unable to reach a new static equilibrium configuration. The objective of this research is to identify and investigate important issues related to collapse of seismically designed steel building systems using multi-scale computational models. Coupled multi-scale finite element simulations are first carried out to investigate the collapse response of moment resisting steel frame sub-assemblages. Simulation results suggest that for collapse resistant construction, designers should strive to use a larger number of smaller beam members rather than concentrate resistance in a few larger members and should specify ASTM A-992 steel rather than specifying generic steels. Improved behavior can also be achieved by increasing the shear tab thickness or directly welding the beam web to the column. Using information gleaned from the sub-assemblage simulations, computationally efficient structural scale models for progressive collapse analysis of seismically designed steel frames systems are developed. The models are calibrated and utilized within the context of the alternate path method to study the collapse resistance of multistory steel moment and braced frame building systems. A new analysis technique termed "pushdown analysis" is proposed and used to investigate collapse modes, failure loads and robustness of seismically designed frames. The collapse and pushdown analyses show that systems designed for high seismic risk are less vulnerable to gravity-induced progressive collapse and more robust than those designed for moderate seismic risk. Motivated by a number of deficiencies in existing ductile fracture models for steel, a new micro-mechanical constitutive model is proposed. Damage mechanics principles are used and a scalar damage variable is introduced to represent micro-structural evolution related to micro-void nucleation, growth and coalescence during the ductile fracture process in steels. Numerical implementation and parametric studies are presented and discussed. Calibration and validation studies show that the proposed model can successfully represent ductile fracture of steels. Although the system studies in this dissertation focused primarily on in-plane collapse response, the models and simulation methodologies developed herein can be extended in future work to address the collapse resistance of three-dimensional models.
A progressive collapse is initiated as a result of local structural damage and develops into a failure that is disproportionate to the initiating local damage. Structural collapse can be initiated by many hazards such as earthquakes, fires, or terrorist attacks. On 9/11, the World Trade Center (WTC) towers failed because the terrorist attack led to progressive collapse. Earthquake is a low probability/high consequence event. Therefore, it is very important to analyze how a progressive collapse caused by a seismic hazard event can unfold. In this study, the progressive collapse of a 4-story steel frame structure is analyzed under earthquake. Using equivalent base shear and alternative path methods, the conditional failure probability of a specified member and the probability of progressive collapse are both determined. Combining those results with the hazard curve of the seismic event, the progressive collapse probability of the entire structure due to earthquake can be determined. The risk assessment concept is used to evaluate the risk of a steel structure under earthquake. Based on risk analysis, the optimum size of members is obtained by using optimization under uncertainty. In this study, the procedure of estimating the probability of progressive collapse of a structure under earthquake is established. Risk estimation helps structural designer to identify critical members which have a substantial effect on structural reliability. The results of the optimal seismic design show that the expected total cost is mostly affected by the dimensions of critical members and the location of the structure.
Author: LAWRENCE E. KINSLER-AUSTIN R. FREY-ALAN B. COPPENS-JAMES V. SANDERS | Size: 19.7 MB | Format:PDF | Quality:Scanner | Publisher: John Wiley & Sons, Inc. | Year: 2000 | pages: 567 | ISBN: ISBN-10: 0471847895 | ISBN-13: 978-0471847892
The classic acoustics reference! This widely-used book offers a clear treatment of the fundamental principles underlying the generation, transmission, and reception of acoustic waves and their application to numerous fields. The authors analyze the various types of vibration of solid bodies and the propagation of sound waves through fluid media.
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PREFACE
Credit for the longevity of this work belongs to the original two authors, Lawrence Kinsler and Austin Frey, both of whom have now passed away. When Austin entrusted us with the preparation of the third edition, our goal was to update the text while maintaining the spirit of the first two editions. The continued acceptance of this book in advanced undergraduate and introductory graduate courses suggests that this goal was met. For this fourth edition, we have continued this updating and have added new material. Considerable effort has been made to provide more homework problems. The total number has been increased from about 300 in the previous editions to over 700 in this edition. The availability of desktop computers now makes it possible for students to investigate many acoustic problems that were previously too tedious and time consuming for classroom use. Included in this category are investigations of the limits of validity of approximate solutions and numerically based studies of the effects of varying the various parameters in a problem. To take advantage of this new tool, we have added a great number of problems (usually marked with a suffix "c" )where the student may be expected to use or write computer programs. Any convenient programming language should work, but one with good graphing software will make things easier. Doing these problems should develop a greater appreciation of acoustics and its applications while also enhancing computer skills.
The following additional changes have been made in the fourth edition:
(1) As an organizational aid to the student, and to save instructors some time, equations, figures, tables, and homework problems are all now numbered by chapter and section. Although appearing somewhat more cumbersome, we believe the organizational advantages far outweigh the disadvantages.
(2) The discussion of transmitter and receiver sensitivity has been moved to Chapter 5 to facilitate early incorporation of microphones in any accompanying laboratory.
(3) The chapters on absorption and sources have been interchanged so that the discussion of beam patterns precedes the more sophisticated discussion of absorption effects.
(4) Derivations from the diffusion equation of the effects of thermal conductivity on the attenuation of waves in the free field and in pipes have been added to the chapter on absorption.
(5) The discussions of normal modes and waveguideshave been collected into a single chapter and have been expanded to include normal modes in cylindrical and spherical cavities and propagation in layers.
(6) Considerations of transient excitations and orthonormality have been enhanced.
(7) Two new chapters have been added to illustrate how the principles of acoustics can be applied to topics that are not normally covered in an undergraduate course. These chapters, on finite-amplitude acoustics and shock waves, are not meant to survey developments in these fields. They are intended to introduce the relevant underlying acoustic principles and to demonstratehow the fundamentals of acoustics can be extended to certain more complicated problems. We have selected these examples from our own areas of teaching and research.
(8) The appendixes have been enhanced to provide more information on physical constants, elementary transcendental functions (equations, tables, and figures), elements of thermodynamics, and elasticity and viscosity.
New materials are frequently at a somewhat more advanced level. As in the third edition, we have indicated with asterisks in the Contents those sections in each chapter that can be eliminated in a lower-level introductory course. Such a course can be based on the first five or six chapters with selected topics from the seventh and eighth. Beyond these, the remaining chapters are independent of each other (with only a couple of exceptions that can be dealt with quite easily), so that topics of interest can be chosen at will. With the advent of the handheld calculator, it was no longer necessary for textbooks to include tables for trigonometric, exponential, and logarithmic functions. While the availability of desktop calculators and current mathematical software makes it unnecessary to include tables of more complicated functions (Bessel functions, etc.), until handheld calculators have these functions programmed into them, tables are still useful. However, students are encouraged to use their desktop calculators to make fine-grained tables for the functions found in the appendixes. In addition, they will find it useful to create tables for such things as the shock parameters in Chapter 17.
Alan B. Coppens
Black Mountain, NC
James V. Sanders
Monterey, CA
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As a result of the increasing number of terrorist attacks registered against American facilities in the United States or abroad, United States government agencies continue to improve the design of their buildings to make them safer and less vulnerable to terrorist attacks. One of the factors typically considered in designing safer buildings and structures, is their ability to prevent total collapse after the loss of load-carrying components (Progressive Collapse) resulting from a terrorist attack. The consequences of not having a building capable of reducing the potential for progressive collapse could be catastrophic, as it was the case of the Oklahoma City bombing in 1995 where 42% of the Alfred P. Murrah Federal Building was destroyed by progressive collapse and only 4% by the explosion or blast. This attack claimed 168 lives and left over 800 injured. Over the last 10 years, two United States government agencies have developed guidelines for the design of their structures to resist progressive collapse: (1) The General Services Administration, "Progressive Collapse Analysis and Design Guidelines," (GSA Guidelines) and (2) The Department of Defense Unified Facilities Criteria 4-023-03 "Design of Buildings to Resist Progressive Collapse" (UFC 4-023-03). Within both approaches, the main direct design procedure is the Alternate Path (AP) method, in which a structure is analyzed for collapse potential after the removal of a column or section of wall. Different analytical procedures may be used, including Linear Static (LS), Nonlinear Static (NLS), and Nonlinear Dynamic (NLD). Typically, NLD procedures give better and more accurate results, but are more complicated and expensive. As a result, designers often choose static procedures, which tend to be simpler, requiring less labor. As progressive collapse is a dynamic and nonlinear event, the load cases for the static procedures require the use of factors to account for inertial and nonlinear effects, similar to the approach used in ASCE Standard 41 "Seismic Rehabilitation of Existing Buildings" (ASCE 41). A number of inconsistencies have been indentified in the way the existing guidelines applied dynamic and non-linear load factors to their static approaches. As part of an existing effort to update the existing guidelines, this study used SAP2000 to perform several AP analyses on a variety of Reinforced Concrete and Steel Moment Frame buildings to investigate the magnitude and variation of the dynamic and non-linear load increase factors. The study concluded that the factors in the existing guidelines tend to yield overly conservative results, which often translate into expensive design and retrofits. This study indentified new load increase factors and proposes a new approach to utilize these factors when performing AP analyses for Progressive Collapse.
Author: R. Ivan Skinner , William H. Robinson,and Graeme H. McVerry | Size: 43.6 MB | Format:PDF | Quality:Scanner | Publisher: John Wiley & Sons | Year: 1993 | pages: 376 | ISBN: 047193433X-978-0471934332
i don't think this book needs to be introduced,but:
Editorial Reviews
Book Description
These authors present much sought after information on the design procedures for seismically isolated structures. Using a logical progression, they describe seismic isolation along with the concepts of earthquake structural dynamics underlying the isolation theory. Methods discussed will provide the basis for continuing development and refinement.
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From the Publisher
These authors present much sought after information on the design procedures for seismically isolated structures. Using a logical progression, they describe seismic isolation along with the concepts of earthquake structural dynamics underlying the isolation theory. Methods discussed will provide the basis for continuing development and refinement.
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Skinner et al. book on seismic isolation is much more than an introduction, is a must to anyone interested on the subjects of seismic isolation and passive energy dissipation. The book is quite complete, and it is easy to read (if you do not mind NZ English), both for students or experienced professionals or professors. All chapters have basic and advanced material. The book is not married with a single base isolation system, a difference with other books available on this topic. I am looking forward to a second edition of this book that may add some new material on the development of other isolation devices and design methods that have been proposed during the last seven years.
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Written by the precursors of modern seismic isolation technology, "An Introduction to seismic isolation" is one of the most challenging treatments in structural dynamics so far. Skinner et al first introduce the reader to the concept of seismic isolation as a whole, explaining the philosophy behind this technique, followed by a brief review of the structural dynamics theory needed for the basic understanding of the more specifically mathematical explanations in chapter 4, where the equations of motion for the theoretical models are explicitly derived. Here, the authors make the difference, providing a good treatment in which a high mathematical understanding level is required. Chapter 3 is a complete description of the different seismic isolation systems available, describing their controlling parameters, composition, tested performance and analytical models for design. Chapter 5 is an excellent guide for analysis and design, from a more practical point of view. Chapter 6 is simply a description of some of the more prominent seismic isolation projects worldwide. Until now, the best reference, sophisticated yet understandable bibliography about seismic isolation.
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This File is dedicated to dear mybest for his supports to me.
This book presents, in a unified manner, a variety of topics in Continuum and Fracture Mechanics: energy methods, conservation laws, mathematical methods to solve two-dimensional and three-dimensional crack problems. Moreover, a series of new subjects is presented in a straightforward manner, accessible to under-graduate students. Emphasizing physical or experimental back-grounds, then analysis and theoretical results, this monograph is intended for use by students and researchers in solid mechanics, mechanical engineering and applied mathematics.
Paperback (Reprint September 8, 2011)
ISBN-10: 9048172071
ISBN-13: 978-9048172078
Note:
Each chapter is single pdf file
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