Because of their structural simplicity, bridges tend to beparticularly vulnerable to damage and even collapse when subjectedto earthquakes or other forms of seismic activity. Recentearthquakes, such as the ones in Kobe, Japan, and Oakland,California, have led to a heightened awareness of seismic risk andhave revolutionized bridge design and retrofit philosophies. In Seismic Design and Retrofit of Bridges, three of the world's topauthorities on the subject have collaborated to produce the mostexhaustive reference on seismic bridge design currently available.Following a detailed examination of the seismic effects of actualearthquakes on local area bridges, the authors demonstrate designstrategies that will make these and similar structures optimallyresistant to the damaging effects of future seismicdisturbances. Relying heavily on worldwide research associated with recentquakes, Seismic Design and Retrofit of Bridges begins with anin-depth treatment of seismic design philosophy as it applies tobridges. The authors then describe the various geotechnicalconsiderations specific to bridge design, such as soil-structureinteraction and traveling wave effects. Subsequent chapters coverconceptual and actual design of various bridge superstructures, andmodeling and analysis of these structures. As the basis for their design strategies, the authors' focus is onthe widely accepted capacity design approach, in which particularlyvulnerable locations of potentially inelastic flexural deformationare identified and strengthened to accommodate a greater degree ofstress. The text illustrates how accurate application of thecapacity design philosophy to the design of new bridges results instructures that can be expected to survive most earthquakes withonly minor, repairable damage. Because the majority of today's bridges were built before thecapacity design approach was understood, the authors also devoteseveral chapters to the seismic assessment of existing bridges,with the aim of designing and implementing retrofit measures toprotect them against the damaging effects of future earthquakes.These retrofitting techniques, though not considered appropriate inthe design of new bridges, are given considerable emphasis, sincethey currently offer the best solution for the preservation ofthese vital and often historically valued thoroughfares. Practical and applications-oriented, Seismic Design and Retrofit ofBridges is enhanced with over 300 photos and line drawings toillustrate key concepts and detailed design procedures. As the onlytext currently available on the vital topic of seismic bridgedesign, it provides an indispensable reference for civil,structural, and geotechnical engineers, as well as students inrelated engineering courses. A state-of-the-art text on earthquake-proof design and retrofit ofbridges Seismic Design and Retrofit of Bridges fills the urgent need for acomprehensive and up-to-date text on seismic-ally resistant bridgedesign. The authors, all recognized leaders in the field,systematically cover all aspects of bridge design related toseismic resistance for both new and existing bridges. * A complete overview of current design philosophy for bridges,with related seismic and geotechnical considerations * Coverage of conceptual design constraints and their relationshipto current design alternatives * Modeling and analysis of bridge structures * An exhaustive look at common building materials and theirresponse to seismic activity * A hands-on approach to the capacity design process * Use of isolation and dissipation devices in bridge design * Important coverage of seismic assessment and retrofit design ofexisting bridges
Bridge structures can give the impression that they are rather simple structural systems, whose seismic responses can be easily predicted. On the contrary, however, many bridges did not perform well in recent earthquakes, showing a need for increased research to understand various potential problems and collapse mechanisms. Indeed, progress has been made lately in design and assessment procedures around the world, and consequently many practices have changed. In this context, the objective of fib Bulletin 39 is to present, discuss and critically compare structural solutions for bridge seismic design and retrofit that have been developed and are now used all over the world, ten years after the publication of the last comprehensive manual on the subject. It is the result of the work of an international team of experts that collaborated intensively for over three years. The first four chapters of the Bulletin present a regional review of design choices, compare and discuss international design practices, and indicate their relative merits and potential problems. Current developments are treated in the next three chapters, with particular emphasis on design for enhanced damage control, for spatial variation of ground motion and for fault crossing. The last part presents a summary of current issues related to existing bridges. Extensive technical developments have been taking place in the last two decades with the goal of making bridges an important transportation infrastructure with limited damage during earthquakes. Realising this goal depends on regional seismicity, transportation systems, seismic performance goals, local cultures, and a wide range of design and construction practices, which are presented and discussed in this Bulletin.
Mitigating the effects of earthquakes is crucial to bridge design. With chapters culled from the best-selling Bridge Engineering Handbook, this volume sets forth the principles and applications of seismic design, from the necessary geotechnical and dynamic analysis background to seismic isolation and energy dissipation, active control, and retrofit technology. In-depth discussions contributed by bridge and earthquake engineers from around the world cover the types and effects of earthquake damage and structural performance criteria. The book also includes an overview of seismic design practices in Japan, including a study of the damage to highway bridges caused by the Hyogo-ken Nanbu earthquake and the changes in retrofit practices precipitated by that earthquake.
Earthquake engineering is the ultimate challenge for structural engineers. Even if natural phenomena involve great uncertainties, structural engineers need to design buildings, bridges, and dams capable of resisting the destructive forces produced by them. These disasters have created a new awareness about the disaster preparedness and mitigation. Before a building, utility system, or transportation structure is built, engineers spend a great deal of time analyzing those structures to make sure they will perform reliably under seismic and other loads. The purpose of this book is to provide structural engineers with tools and information to improve current building and bridge design and construction practices and enhance their sustainability during and after seismic events. In this book, Khan explains the latest theory, design applications and Code Provisions. Earthquake-Resistant Structures features seismic design and retrofitting techniques for low and high raise buildings, single and multi-span bridges, dams and nuclear facilities. The author also compares and contrasts various seismic resistant techniques in USA, Russia, Japan, Turkey, India, China, New Zealand, and Pakistan. Written by a world renowned author and educator Seismic design and retrofitting techniques for all structures Tools improve current building and bridge designs Latest methods for building earthquake-resistant structures Combines physical and geophysical science with structural engineering
The Washington State Department of Transportation (WSDOT) began a bridge seismic retrofit program in 1991 in order to address the earthquake risks associated with state-owned bridges. The majority of these bridges were constructed in the 1960s, prior to the development of modern seismic design standards during the 1970s and 1980s, and one class of bridges built during that era represents a particular cause for concern. In that class of bridges, circular, hollow-core precast, prestressed concrete piles were driven into the ground, with sufficient length left projecting above ground level to form the columns. Hence, they are referred to in this thesis as "pile-columns." Cap beams were then cast in place on the pile-columns and were connected to them by means of concrete plugs with longitudinal reinforcement cast into the tops of the columns. Many of these hollow pile-column bridges form part of the state's "Lifeline Routes" for seismic events and are consequently slated for retrofit in the near future. Previous, but limited, experimental research have shown that hollow, prestressed concrete specimens show minimal ductility under cyclic lateral loading and fail suddenly, because the wall of the column spalls both inwards and outwards. However, cyclic lateral loading performed during an earlier phase of this research program on an as-built scaled model specimen of the column-to-cap-beam connection showed better ductility than expected. In this portion of the research program, reported in this thesis, experiments were conducted to better understand the behavior of the hollow core pile-columns under pure bending (relevant in the pile region below-grade) as well as combined bending and shear (relevant in the column region above-grade). Finally, a column-to-cap-beam connection retrofitted with a carbon fiber jacket was tested under cyclic lateral loading. Under elastic conditions, the peak moment demand in the pile-column occurs at column-to-cap-beam connection; the moments below-grade are approximately half as large. As a result, the retrofit concept for these bridges is concentrated on that connection. The tested retrofit option involved jacketing the as-built plug region in a carbon fiber wrap on the basis that that procedure is simple and reliable, it slightly lowers the peak moments below-grade, and, if a fiber jacket could be used over only the upper part of the column, it would avoid invoking environmental restrictions for bridges over waterways. Concerns with this, and any other retrofit option, include vulnerability to combined bending and shear failure of the hollow cross section just beyond the end of the plug, as well as susceptibility to pure bending failure of the hollow pile below-grade. Three experimental programs were conducting during this investigation. The first and second were conducted to determine the pure bending, and combined shear and bending, strengths of a hollow pile-column section. The results of these tests aided in calibrating the transverse load capacity of hollow prestressed concrete specimens under two separate load configurations. The third experiment was conducted on a scaled cantilever column-to-cap beam connection, retrofitted with a fiber jacket around the plug region, under reversed cyclic displacement. The results of the third experiment showed that the retrofitted pile-column performed slightly better than the as-built specimen, and that the critical mode of failure was not internal spalling, as suggested by previous researchers, but rather by column cracking, followed by strand debonding. Review of the test results from the as-built specimen concluded that that specimen, too, had failed by strand debonding. Debonding failure proved to be non-ductile, because the strands buckled during the half-cycle following debonding, then fractured as they re-straightened. It was further concluded that the fiber jacket had provided little benefit because strand debonding, and not concrete confinement, was the primary failure mechanism. A third retrofit option was then developed, but limitations on resources prevented it from being tested. Strand debonding can occur only after the column wall cracks, which requires high net tension stress, due primarily to bending. A thick steel jacket, made composite with the concrete components, would increase the flexural stiffness of the region and reduce the bending stress in the concrete column wall, thereby preventing cracking. A methodology for selecting the jacket thickness was developed, and it is recommended that this retrofit option be tested and, if the test is successful, it should be adopted.
The primary objectives of the report are to (1) provide current information on the theory and techniques for seismic analysis of highway bridges, including background material on basic structural dynamics, (2) identify the appropriate criteria necessary to decide if a bridge needs retrofitting and the type of retrofit measures to employ, and (3) demonstrate design details and installation specifications for retrofitting existing highway bridges to minimize earthquake damage. This report is in two volumes: Vol 1 "Earthquake and Structrural Analysis" Vol. 2 "Design Manual". Volume two is a design manual and contains illustrations of various retrofit concepts and specific design procedures which can be applied to existing bridges.
More than a third of America's bridges are considered substandard--either structurally deficient, functionally obsolete or both. Offers first-rate, practical guidance regarding the inspection and rehabilitation of aging bridge infrastructure including all elements involving structure, various materials and design types. Features seismic retrofit and coverage of environmental issues. Each chapter is written by an authority on the subject. Contains top-quality, detailed line illustrations plus photographs of actual rehab projects.
In most parts of the developed world, the building stock and the civil infrastructure are ageing and in constant need of maintenance, repair and upgrading. Moreover, in the light of our current knowledge and of modern codes, the majority of buildings stock and other types of structures in many parts of the world are substandard and deficient. This is especially so in earthquake-prone regions, as, even there, seismic design of structures is relatively recent. In those regions the major part of the seismic threat to human life and property comes from old buildings. Due to the infrastructure's increasing decay, frequently combined with the need for structural upgrading to meet more stringent design requirements (especially against seismic loads), structural retrofitting is becoming more and more important and receives today considerable emphasis throughout the world. In response to this need, a major part of the fib Model Code 2005, currently under development, is being devoted to structural conservation and maintenance. More importantly, in recognition of the importance of the seismic threat arising from existing substandard buildings, the first standards for structural upgrading to be promoted by the international engineering community and by regulatory authorities alike are for seismic rehabilitation of buildings. This is the case, for example, of Part 3: Strengthening and Repair of Buildings of Eurocode 8 (i. e. of the draft European Standard for earthquake-resistant design), and which is the only one among the current (2003) set of 58 Eurocodes attempting to address the problem of structural upgrading. It is also the case of the recent (2001) ASCE draft standard on Seismic evaluation of existing buildings and of the 1996 Law for promotion of seismic strengthening of existing reinforced concrete structures in Japan. As noted in Chapter 1 of this Bulletin, fib - as CEB and FIP did before - has placed considerable emphasis on assessment and rehabilitation of existing structures. The present Bulletin is a culmination of this effort in the special but very important field of seismic assessment and rehabilitation. It has been elaborated over a period of 4 years by Task Group 7.1 Assessment and retrofit of existing structures of fib Commission 7 Seismic design, a truly international team of experts, representing the expertise and experience of all the important seismic regions of the world. In the course of its work the team had six plenary two-day meetings: in January 1999 in Pavia, Italy; in August 1999 in Raleigh, North Carolina; in February 2000 in Queenstown, New Zealand; in July 2000 in Patras, Greece; in March 2001 in Lausanne, Switzerland; and in August 2001 in Seattle, Washington. In October 2002 the final draft of the Bulletin was presented to public during the 1st fib Congress in Osaka. It was also there that it was approved by fib Commission 7 Seismic Design. The contents is structured into main chapters as follows: 1 Introduction - 2 Performance objectives and system considerations - 3 Review of seismic assessment procedures - 4 Strength and deformation capacity of non-seismically detailed components - 5 Seismic retrofitting techniques - 6 Probabilistic concepts and methods - 7 Case studies
Over 140 experts, 14 countries, and 89 chapters are represented in the second edition of the Bridge Engineering Handbook. This extensive collection highlights bridge engineering specimens from around the world, contains detailed information on bridge engineering, and thoroughly explains the concepts and practical applications surrounding the subject. Published in five books: Fundamentals, Superstructure Design, Substructure Design, Seismic Design, and Construction and Maintenance, this new edition provides numerous worked-out examples that give readers step-by-step design procedures, includes contributions by leading experts from around the world in their respective areas of bridge engineering, contains 26 completely new chapters, and updates most other chapters. It offers design concepts, specifications, and practice, as well as the various types of bridges. The text includes over 2,500 tables, charts, illustrations, and photos. The book covers new, innovative and traditional methods and practices; explores rehabilitation, retrofit, and maintenance; and examines seismic design and building materials. The fourth book, Seismic Design contains 18 chapters, and covers seismic bridge analysis and design. What’s New in the Second Edition: Includes seven new chapters: Seismic Random Response Analysis, Displacement-Based Seismic Design of Bridges, Seismic Design of Thin-Walled Steel and CFT Piers, Seismic Design of Cable-Supported Bridges, and three chapters covering Seismic Design Practice in California, China, and Italy Combines Seismic Retrofit Practice and Seismic Retrofit Technology into one chapter called Seismic Retrofit Technology Rewrites Earthquake Damage to Bridges and Seismic Design of Concrete Bridges chapters Rewrites Seismic Design Philosophies and Performance-Based Design Criteria chapter and retitles it as Seismic Bridge Design Specifications for the United States Revamps Seismic Isolation and Supplemental Energy Dissipation chapter and retitles it as Seismic Isolation Design for Bridges This text is an ideal reference for practicing bridge engineers and consultants (design, construction, maintenance), and can also be used as a reference for students in bridge engineering courses.