Seismic Vulnerability Assessment of Retrofitted Bridges Using Probabilistic Methods

Seismic Vulnerability Assessment of Retrofitted Bridges Using Probabilistic Methods
Author: Jamie Ellen Padgett
Publisher:
Total Pages: 270
Release: 2007
Genre:
ISBN: 9780549008798

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There is an urgent need for the development of fragility curves for retrofitted bridges, particularly for the CSUS. These fragility curves are conditional probability statements of potential levels of damage over a range of earthquake intensities. The development of reliable retrofitted bridge fragility curves would allow for assessment of the effects of various retrofit measures on the performance of different CSUS bridge types. Therefore, a primary objective of this work is to develop a methodology for fragility assessment of bridge retrofit, in order to support seismic risk mitigation efforts in the region.

Seismic Vulnerability Assessment of Bridges for Retrofitting and New Design

Seismic Vulnerability Assessment of Bridges for Retrofitting and New Design
Author: Pedram Farokh
Publisher:
Total Pages: 96
Release: 2017
Genre: Bridges
ISBN:

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Many bridges in North Eastern region of U.S. were designed prior to the adoption of the AASHTO LRFD Guide Specifications for seismic design and may be vulnerable to damage during an earthquake event. This study evaluates the seismic vulnerabilities of those bridges and the structural factors that could affect their performance during a seismic event. The effects of load demands and age deteriorations were also studied. Aging of certain bridge components such as bearings, columns, and bent caps can affect the capacity and demands of these components and accordingly might affect the global behavior and capacity of a bridge during an earthquake event. The concept of fragility curves was studied as a potential tool for evaluating the seismic performance of new bridges, existing bridges and retrofitted bridges for various bridge types subjected to different peak ground acceleration levels. Fragility curves represent the probability of a structure to experience damage levels higher than specific damage state at different peak ground acceleration. Possible retrofit measures for various bridge components were reviewed, and analyzed for their effectiveness. These include superstructure restrainers, stoppers, shear keys, isolation bearings, bent cap strengthening and column jacketing. Existing research shows that the concept of fragility curves can be used to identify bridge vulnerability and level of damage. They can also be used to identify performance and level of damage of various retrofit measures. The effect of aging of certain components such as stiffening and locking of bearings and corrosion of confining steel in columns need to be included when evaluating bridge load demands and capacities. Different types of concrete bridges (typical in North Eastern United States) were analyzed using elastic response spectrum and nonlinear push-over analysis for low, medium-to-high, and high seismicity levels. The effects of pier configuration, continuity between the superstructure and the substructure, and the number of spans were investigated. Analysis results showed that in the longitudinal direction, the displacement demand increased for multi-column bents compared to single-column bents. However, the overall D/C ratio dropped in both transverse and longitudinal directions. The results also showed that in the longitudinal direction the benefit of having multi-column bent over single-column bents in integral bridges is dependent on the seismicity levels. The D/C (demand/capacity) ratio for single column bents in the longitudinal direction was much lower for integral (monolithic) bents compared to non-integral bents. In the transverse directions, the difference in the D/C ratio was not significant. For multi-column bents, the percent change by having integral bents over non-integral bents was dependent on the seismicity levels. For high seismicity zones, the benefits of having Integral bents becomes more significant. This investigation presents guidance on incorporating the effects of aging and retrofitting in the finite element modeling of bridges subjected to various levels of earthquake ground motions.

Bridge Maintenance, Safety, Management, Resilience and Sustainability

Bridge Maintenance, Safety, Management, Resilience and Sustainability
Author: Fabio Biondini
Publisher: CRC Press
Total Pages: 4119
Release: 2012-06-21
Genre: Technology & Engineering
ISBN: 0203103386

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Bridge Maintenance, Safety, Management, Resilience and Sustainability contains the lectures and papers presented at The Sixth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2012), held in Stresa, Lake Maggiore, Italy, 8-12 July, 2012. This volume consists of a book of extended abstracts (800 pp) Extensive collection of revised expert papers on recent advances in bridge maintenance, safety, management and life-cycle performance, representing a major contribution to the knowledge base of all areas of the field.

Seismic Vulnerability Assessment and Retrofit Recommendations for State Highway Bridges

Seismic Vulnerability Assessment and Retrofit Recommendations for State Highway Bridges
Author:
Publisher:
Total Pages: 204
Release: 2009
Genre: Bridges
ISBN:

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Much of Utah's population dwells in a seismically active region, and many of the bridges connecting transportation lifelines predate the rigorous seismic design standards that have been developed in the past 10-20 years. Other states in the west have instituted seismic retrofit programs in response to damage to transportation networks in past California earthquakes. In a parallel report, seismic retrofit guidelines were developed for Utah based on the Seismic Retrofitting Manual for Highway Structures published by FHWA. In this report, representative case study bridges are evaluated in detail using the guidelines. The case study evaluations include the following for each bridge: (1) selection and presentation of analysis method, (2) development of numerical model in LARSA 4D and/or additional programs as needed, (3) evaluation of the seismic response of the unretrofitted bridge, (4) design of a possible retrofit scheme. The bridges evaluated include a four-span simply supported prestressed concrete girder bridge, a four-span continuous concrete T-beam, and an eight-span curved steel girder bridge with in-span pin and hanger joints. A variety of different evaluation methods are presented including linear response spectrum analysis for demand assessment, capacity spectrum method and pushover analysis for capacity assessment, and nonlinear response history analysis. A variety of retrofit techniques are presented including column jacketing, cable restrainers, selectively closing pin and hanger joints, and seismic isolation. The varied examples and techniques presented in this report are meant to be representative of assessment and applicable retrofit approaches for many of the bridges in the state inventory that may be seismically deficient.

Routledge Handbook of Sustainable and Resilient Infrastructure

Routledge Handbook of Sustainable and Resilient Infrastructure
Author: Paolo Gardoni
Publisher: Routledge
Total Pages: 951
Release: 2018-12-17
Genre: Business & Economics
ISBN: 1351392778

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To best serve current and future generations, infrastructure needs to be resilient to the changing world while using limited resources in a sustainable manner. Research on and funding towards sustainability and resilience are growing rapidly, and significant research is being carried out at a number of institutions and centers worldwide. This handbook brings together current research on sustainable and resilient infrastructure and, in particular, stresses the fundamental nexus between sustainability and resilience. It aims to coalesce work from a large and diverse group of contributors across a wide range of disciplines including engineering, technology and informatics, urban planning, public policy, economics, and finance. Not only does it present a theoretical formulation of sustainability and resilience but it also demonstrates how these ideals can be realized in practice. This work will provide a reference text to students and scholars of a number of disciplines.

Seismic Design and Retrofit of Bridges

Seismic Design and Retrofit of Bridges
Author: M. J. N. Priestley
Publisher: John Wiley & Sons
Total Pages: 704
Release: 1996-04-12
Genre: Technology & Engineering
ISBN: 9780471579984

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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

Life Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision

Life Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision
Author: Robby Caspeele
Publisher: CRC Press
Total Pages: 3160
Release: 2018-10-31
Genre: Technology & Engineering
ISBN: 1351857576

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This volume contains the papers presented at IALCCE2018, the Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE2018), held in Ghent, Belgium, October 28-31, 2018. It consists of a book of extended abstracts and a USB device with full papers including the Fazlur R. Khan lecture, 8 keynote lectures, and 390 technical papers from all over the world. Contributions relate to design, inspection, assessment, maintenance or optimization in the framework of life-cycle analysis of civil engineering structures and infrastructure systems. Life-cycle aspects that are developed and discussed range from structural safety and durability to sustainability, serviceability, robustness and resilience. Applications relate to buildings, bridges and viaducts, highways and runways, tunnels and underground structures, off-shore and marine structures, dams and hydraulic structures, prefabricated design, infrastructure systems, etc. During the IALCCE2018 conference a particular focus is put on the cross-fertilization between different sub-areas of expertise and the development of an overall vision for life-cycle analysis in civil engineering. The aim of the editors is to provide a valuable source of cutting edge information for anyone interested in life-cycle analysis and assessment in civil engineering, including researchers, practising engineers, consultants, contractors, decision makers and representatives from local authorities.

Seismic Fragility Assessment of Highway Bridges

Seismic Fragility Assessment of Highway Bridges
Author: Seyyed Nima Mahmoudi
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

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"Fragility curves are useful tools for reliability evaluation of structures as well as for identifying the most vulnerable components. This study focuses on the seismic fragility analysis of highway bridges. Two main approaches are used for this purpose: component-based and system-based fragility analyses. The seismic vulnerability of two existing bridges located in Montreal are assessed as case studies.The main goal of this study is to develop reliable seismic fragility curves for highway bridge structures considering all significant uncertainties involved. Uncertainties include those associated with modelling structural behavior, seismic inputs and definition of component capacities. The procedures are implemented for the fragility assessment of two existing bridges as case studies. For this purpose, deterioration due to corrosion of reinforcing steel and its effects on structural behavior are included, as well as validation of the Finite Element Model using dynamic properties obtained from ambient noise measurements. Proposed methods for the selection of appropriate set of ground motion records, the type of model analysis and probabilistic modeling of component capacities are presented and illustrated for the two case studies.Two stochastic methods are proposed for validating the Finite Element Model of a bridge. The first method is based on classical hypothesis testing procedures while the second uses a Bayesian updating approach. The stochastic methods are also used to update the input parameters, detect probable major damage in the bridges and determine the confidence interval on model responses as a function of laboratory test data and field observations.In order to limit the uncertainties involved in seismic inputs, a state-of-the-art ground motion record selection procedure based on Conditional Mean Spectrum (CMS) is used. Incremental Dynamic Analysis (IDA) is performed to evaluate the record to record variability in seismic responses and to capture the nonlinearity in structural component behaviors.The first part of the thesis describes the application of component-based fragility analysis for the seismic vulnerability assessment of highway bridge structures. IDA is performed on the validated Finite Element model of the structure using an appropriate set of ground motion records. The results are used for estimating the relationships between ground motion intensity measures and component demands. A Joint Probabilistic Seismic Demand Model (JPSDM) is fitted to the results in order to develop component and system fragility curves of the structure.Since the component based fragility analysis of complex structures comprising a large number of components requires enormous computational efforts, in the second part of this study, a system-based approach for developing seismic system fragility curves is proposed which uses Support Vector Machines (SVM). SVM is a state-of-the-art machine learning technique which is used to discover patterns in highly dimensional and complex data sets. In this application, SVM is used to determine the relationship between ground motion intensity measures and peak structural responses. Seismic fragility curves are developed using Probabilistic SVM (PSVM). Finally, the efficiency of the proposed PSVM method for its application to vector-valued ground motion Intensity Measures (IM) as well as traditional single-valued IM are investigated." --