Seismic Design and Retrofit of Bridges


Book Description

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













Resonance of Cable-Stayed Bridges Subjected to Delayed Time-Histories Using Multi-Support Excitation


Book Description

The requirement for the seismic analysis of cable-stayed bridges under spatially varying loads is not well defined in the bridge design codes around the world. The Canadian Highway Bridge Design Code briefly stipulates that it is the responsibility of the designer to check the effect of the spatially varying loads while no details are provided. Given this, the objective of this study is to evaluate the seismic performance of cable-stayed bridges using multi-support excitation. For the purpose of the study, Quincy Bayview Bridge located in Illinois, USA is selected for the analysis. Ten ground motion acceleration time-histories obtained from earthquakes in the US, Japan, and Taiwan are used as initial seismic excitation to be applied on the bridge. They are then converted to displacement time-histories and applied at each support by considering the phase delay of the wave traveling from one support to another. The seismic analysis using multi-support excitation shows that significant vertical deck displacement is produced, which is generally ignored in the analysis of cable-stayed bridges under uniform excitation. The response curve for the vertical deck displacement vs wave velocity demonstrates that a resonance-like condition is triggered at relatively low velocity. A mathematical formula is developed to account for the potential of resonance for the displacement of the deck in the vertical direction. Furthermore, a time delay factor of 0.72 is proposed to estimate the critical seismic wave velocity that would trigger the resonance. In addition, the results from this study indicate that attention is required for the bridge response in the direction orthogonal (e.g., vertical direction) to the direction of the seismic loading (e.g., horizontal direction), while multi-support excitation should be considered for this purpose.




Bridge Engineering


Book Description

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




Innovative Bridge Design Handbook


Book Description

Innovative Bridge Design Handbook: Construction, Rehabilitation, and Maintenance, Second Edition, brings together the essentials of bridge engineering across design, assessment, research and construction. Written by an international group of experts, each chapter is divided into two parts: the first covers design issues, while the second presents current research into the innovative design approaches used across the world. This new edition includes new topics such as foot bridges, new materials in bridge engineering and soil-foundation structure interaction. All chapters have been updated to include the latest concepts in design, construction, and maintenance to reduce project cost, increase structural safety, and maximize durability. Code and standard references have been updated. - Completely revised and updated with the latest in bridge engineering and design - Provides detailed design procedures for specific bridges with solved examples - Presents structural analysis including numerical methods (FEM), dynamics, risk and reliability, and innovative structural typologies







Seismic Retrofitting and Design of Highway Bridges in New Jersey


Book Description

This report presents the results of the second phase of a comprehensive analytical study on the seismic response of highway bridges in New Jersey. Most bridges in New Jersey are multi-span simply supported (MSSS) where due to impact at the joints the seismic response is highly nonlinear. Therefore, detailed seismic analysis of essential bridges should employ nonlinear computer models that consider the important behavioral characteristics. Among these are: behavior of steel bearings, impact between adjacent spans and between the end-span and the abutment, soil-structure interaction, frictional characteristics following bearing failure, plastic hinges and/or shear failure at the columns, and combined effect of horizontal and transverse ground motion excitations. In light of these, the overall objective of this phase of the study was to evaluate the nonlinear seismic response of actual bridges with emphasis on soil-structure interaction and three-dimensional effect of ground motion. Furthermore, capacity/demand ratios for various components were determined based on the Federal Highway Administration's seismic retrofitting manual for highway bridges.