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Author: Alireza Mohebbi
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 178
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Book Description
Previous research and experience demonstrates that post-earthquake downtime can cripple the transportation network, damage the economic viability of the region, and possibly have more far-reaching consequences due to the trickle down effects. Thus, the current bridge research addresses not only life safety, but also continued operation after earthquakes. A new strategy for seismic protection of bridge piers is proposed that uses sliding bearings as structural fuses that can capacity protect the pier columns and limit their response to the linear elastic range. The strategy was applicable to bridges with dropped bent cap, and integral and semi-integral abutments. In this study, the influence of the structural fuses on the seismic response of a representative 3-span highway bridge with 3 column piers and integral abutments was investigated. Utilizing OpenSees software, the bridge was modeled with and without structural fuses, and the model included the effect of soil interaction at the abutments. Two different types of analysis were applied to the model: (1) static pushover analysis to determine the elastic capacity and the nonlinear behavior of bridge components such as columns, piles, and abutments in both the longitudinal and transverse directions, and (2) nonlinear response history analysis to compare the seismic responses of the bridge components with and without structural fuses. Nonlinear response history analysis was performed on the model for a suite of 20 ground motions scaled to 100%, 150%, and 200% of the design spectrum. Six different friction coefficients (2%, 6%, 9%, 14%, 18%, and 22%) of the structural fuses were considered to evaluate the influence of friction coefficient on the bridge and abutment responses. Results showed that the structural fuses constrained the columns to linear elastic response in both the longitudinal and transverse direction. Furthermore, the abutment ductility demand in the fused bridge was nearly identical to that of the conventional bridge and insensitive to the friction coefficient in both the longitudinal and transverse directions. This case study demonstrated that structural fuses have the potential to improve the seismic performance of bridges by eliminating plastic hinging and associated damage in pier columns without significant changes to the abutment displacement demands.
Author: Alireza Mohebbi
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 178
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Book Description
Previous research and experience demonstrates that post-earthquake downtime can cripple the transportation network, damage the economic viability of the region, and possibly have more far-reaching consequences due to the trickle down effects. Thus, the current bridge research addresses not only life safety, but also continued operation after earthquakes. A new strategy for seismic protection of bridge piers is proposed that uses sliding bearings as structural fuses that can capacity protect the pier columns and limit their response to the linear elastic range. The strategy was applicable to bridges with dropped bent cap, and integral and semi-integral abutments. In this study, the influence of the structural fuses on the seismic response of a representative 3-span highway bridge with 3 column piers and integral abutments was investigated. Utilizing OpenSees software, the bridge was modeled with and without structural fuses, and the model included the effect of soil interaction at the abutments. Two different types of analysis were applied to the model: (1) static pushover analysis to determine the elastic capacity and the nonlinear behavior of bridge components such as columns, piles, and abutments in both the longitudinal and transverse directions, and (2) nonlinear response history analysis to compare the seismic responses of the bridge components with and without structural fuses. Nonlinear response history analysis was performed on the model for a suite of 20 ground motions scaled to 100%, 150%, and 200% of the design spectrum. Six different friction coefficients (2%, 6%, 9%, 14%, 18%, and 22%) of the structural fuses were considered to evaluate the influence of friction coefficient on the bridge and abutment responses. Results showed that the structural fuses constrained the columns to linear elastic response in both the longitudinal and transverse direction. Furthermore, the abutment ductility demand in the fused bridge was nearly identical to that of the conventional bridge and insensitive to the friction coefficient in both the longitudinal and transverse directions. This case study demonstrated that structural fuses have the potential to improve the seismic performance of bridges by eliminating plastic hinging and associated damage in pier columns without significant changes to the abutment displacement demands.
Author: Mark Yashinsky
Publisher: National Information Centre of Earthquake Engineering
ISBN:
Category : Bridges
Languages : en
Pages : 204
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Book Description
With special reference to United States.
Author: M. J. N. Priestley
Publisher: John Wiley & Sons
ISBN: 9780471579984
Category : Technology & Engineering
Languages : en
Pages : 704
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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
Author: W.F. Chen
Publisher: CRC Press
ISBN: 1420039784
Category : Technology & Engineering
Languages : en
Pages : 479
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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
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 28
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Book Description
This executive summary gives an overview of the results of FHWA Contract DTFH61 92 C 00112, Seismic Research Program, which performed a series of special studies addressing the seismic design of new construction. The objectives of this project were to perform a series of special studies pertaining to the seismic vulnerability of highway structures, and to develop technical information on which future specifications for the seismic design of bridges could be based. This project divided work into 5 areas and 13 tasks, focusing on the following elements: review of current seismic design criteria, the seismic hazard exposure of the American highway system, foundation design and soil behavior, structural design, structural analysis and response, the relative importance of specific bridges and an assessment of the impact of current and recently completed research. The Seismic Research Program had a national focus, and aimed in part to address the differences in seismicity, bridge types, and typical design details between the central and eastern United States (CEUS) and those previously studied in California and the western United States. In many cases, west coast design practices required considerable modification before implementation in the CEUS. The project resulted in 34 research reports, of which 31 are summarized in this document. Seventeen of the reports have been published as National Center for Earthquake Engineering Research (NCEER) or Multidisciplinary Center for Earthquake Engineering Research (MCEER) reports. The research agencies final reports for the other taks are available from MCEER upon request.
Author: Yazhou Xie
Publisher:
ISBN:
Category :
Languages : en
Pages : 232
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Book Description
This dissertation systematically addresses the modeling, quantifying, and protection of highway bridges against earthquake hazards. Firstly, the research substantially improves the p-y spring based simulation method to predict the seismic responses of highway bridges that accounts for various soil-structure interaction effects. Closed-form formulae are provided for the p-y spring input parameters to capture the bridge-embankment interaction effects, based on which an integrated step-by-step modeling procedure is developed. The procedure is applied to simulate the seismic responses of a well instrumented highway overcrossing and validated against the recorded responses during the 1992 Petrolia earthquake. Secondly, the study derives a response modification factor to quantify the relative impact of liquefaction induced lateral spreading with respect to seismic shaking on column drifts for highway bridges. The column drift response under lateral spreading is correlated to the crust layer energy imposed on the pile foundation at bridge piers. Under seismic shaking, the column drift ratio is directly related to the peak ground acceleration. By normalizing the column drift under the lateral spreading to that of under the seismic shaking, the proposed modification factor captures key features of how columns respond under both lateral spreading and seismic shaking, and offers reliable column drift demand predictions. Thirdly, this study investigates the effectiveness and optimal design of seismic protective devices for highway bridges. Component-level fragility functions are developed by using the probabilistic seismic demand analysis. To transparently quantify the bridge performance at the system level, seismic repair cost ratios are derived to combine damage probabilities, damage ratios and replacement costs of critical bridge components. Thereafter, a multi-objective genetic optimization method with the Pareto optimal concept is employed to identify the optimal design parameters of protective devices. Subsequently, the research derives a consistent performance index to facilitate the performance-based design and optimization of seismic protective devices. By converting the system-level repair cost ratio to be a function of median-level engineering demand parameters, a uniform design surface is generated for various protection designs. The derived surface can be easily implemented in the performance-based seismic protection design and optimization without iteratively updating the design goal when a new group of design parameters are considered. The robustness of the proposed method is examined in a case study to identify the optimal protection designs by using a genetic optimization scheme. Lastly, the study derives the seismic demand models for bridge rocking columns with foundation on rigid supports when subject to horizontal near-fault strong motions. The system equations of motion are derived and solved to incorporate the column flexibility and the rocking impact mechanism. By representing the near-fault ground motions with corresponding pulses, dimensional analyses are carried out to regress the closed-form expressions of system's drift and uplift demands. A rigorous validation process is implemented to demonstrate that the proposed models can be used with confidence to predict the seismic demands of the rocking system directly from structural and ground motion characteristics.
Author: National Cooperative Highway Research Program
Publisher: Transportation Research Board
ISBN: 0309067537
Category : Bridges
Languages : en
Pages : 55
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Book Description
Author: United States. Federal Highway Administration. Structures and Applied Mechanics Division
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 56
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Book Description
Author: M. Lee Marsh
Publisher: Transportation Research Board
ISBN: 0309223806
Category : Technology & Engineering
Languages : en
Pages : 138
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Book Description
"TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 440, Performance-Based Seismic Bridge Design (PBSD) summarizes the current state of knowledge and practice for PBSD. PBSD is the process that links decision making for facility design with seismic input, facility response, and potential facility damage. The goal of PBSD is to provide decision makers and stakeholders with data that will enable them to allocate resources for construction based on levels of desired seismic performance"--Publisher's description.
Author: Kosalram Krishnan
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 392
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Book Description
