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Author: Reihaneh Sarraf Shirazi
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 642
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Book Description
Curved bridges are constructed to conform to geometric constraints resulting from traffic and structural restrictions. They are different from their straight counterparts since the response coupling in the longitudinal and transverse directions and rotation of the superstructure may lead to significantly different seismic response. Observations from past earthquakes highlighted the seismic vulnerability of these bridges due to this coupled response. The consequence of bridge damage on the performance of transportation system is commonly assessed through Seismic Risk Assessment (SRA) of lifeline systems. Thus, seismic fragility curves are essential input to SRA to estimate damage to highway bridges and consequently to the network. The literature review shows shortcomings in fragility studies on the effect of horizontal curvature of bridges, specifically concrete box-girder bridges. This study aims to fill in the gap on the current state-of-the-knowledge in the seismic response and vulnerability of curved concrete box-girder bridges. Since this bridge type is common in California, the modern details adopted by CALTRANS along with the current seismic design considerations from SDC (2013) are used to select the representative benchmark bridges. To incorporate the uncertainty in geometrical, structural, and material properties of bridges into the analytical models, five sets of statistical bridge samples (each includes 160 bridges) with various subtended angles are developed. These bridge models are subjected to four sets of ground motions representing different site soil conditions and spectral characteristics. A total of 800 response history analyses are performed and the results are used to develop analytical component and system fragility functions for a range of subtended angles. A comprehensive study on the effect of horizontal curvature on the bridge dynamic characteristics and component seismic response is conducted. The median of system (bridge) fragility curves are proposed as a function of the subtended angle for each ground motion set. These functions can be used as input into SRA tools. The fragility analysis shows that the seismic vulnerability of bridges depends on the soil condition of the site and ground motion characteristics as well as the horizontal curvature of the bridge. Columns are found to have the most significant contribution to the system fragility curves. The analyses confirm that the current seismic details including PTFE/spherical bearings and isolated shear keys, suggested by CALTRANS, achieve the objectives of capacity-protected design of piles. Since the dynamic characteristics of bridges are sensitive to the curvature, curved bridges with subtended angles greater than 30 degrees require explicit modeling of curved geometry. In curved bridges, the coupling of transverse and longitudinal modes reduces the dominance of the fundamental mode in the bridge response and leads to the contribution of higher modes. The statistical evaluation of structural demands indicates that the curvature and the torsion demands on columns are amplified in curved bridges.
Author: Reihaneh Sarraf Shirazi
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 642
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Book Description
Curved bridges are constructed to conform to geometric constraints resulting from traffic and structural restrictions. They are different from their straight counterparts since the response coupling in the longitudinal and transverse directions and rotation of the superstructure may lead to significantly different seismic response. Observations from past earthquakes highlighted the seismic vulnerability of these bridges due to this coupled response. The consequence of bridge damage on the performance of transportation system is commonly assessed through Seismic Risk Assessment (SRA) of lifeline systems. Thus, seismic fragility curves are essential input to SRA to estimate damage to highway bridges and consequently to the network. The literature review shows shortcomings in fragility studies on the effect of horizontal curvature of bridges, specifically concrete box-girder bridges. This study aims to fill in the gap on the current state-of-the-knowledge in the seismic response and vulnerability of curved concrete box-girder bridges. Since this bridge type is common in California, the modern details adopted by CALTRANS along with the current seismic design considerations from SDC (2013) are used to select the representative benchmark bridges. To incorporate the uncertainty in geometrical, structural, and material properties of bridges into the analytical models, five sets of statistical bridge samples (each includes 160 bridges) with various subtended angles are developed. These bridge models are subjected to four sets of ground motions representing different site soil conditions and spectral characteristics. A total of 800 response history analyses are performed and the results are used to develop analytical component and system fragility functions for a range of subtended angles. A comprehensive study on the effect of horizontal curvature on the bridge dynamic characteristics and component seismic response is conducted. The median of system (bridge) fragility curves are proposed as a function of the subtended angle for each ground motion set. These functions can be used as input into SRA tools. The fragility analysis shows that the seismic vulnerability of bridges depends on the soil condition of the site and ground motion characteristics as well as the horizontal curvature of the bridge. Columns are found to have the most significant contribution to the system fragility curves. The analyses confirm that the current seismic details including PTFE/spherical bearings and isolated shear keys, suggested by CALTRANS, achieve the objectives of capacity-protected design of piles. Since the dynamic characteristics of bridges are sensitive to the curvature, curved bridges with subtended angles greater than 30 degrees require explicit modeling of curved geometry. In curved bridges, the coupling of transverse and longitudinal modes reduces the dominance of the fundamental mode in the bridge response and leads to the contribution of higher modes. The statistical evaluation of structural demands indicates that the curvature and the torsion demands on columns are amplified in curved bridges.
Author: Masanobu Shinozuka
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 222
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Book Description
Author: Yifan Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
"Curved concrete box-girder bridges are widely applied in highway systems to enable traffic to move from one highway to another. The Akşemsettin Viaduct (termed A Viaduct in the current study) in Istanbul, Turkey, is a typical 11-span curved continuous bridge with a total length of 596.8 m. Located in the high seismicity zone, the A Viaduct exhibits complex seismic behaviour because varying ground motion inputs are expected to excite the bridge at different column/abutment foundations. This study investigates the seismic responses of the A Viaduct under different ground motion scenarios using nonlinear time history analyses (NTHAs). In particular, the software of OpenSees is used to develop a high-fidelity finite element model for the A Viaduct, from which seismic responses of multiple critical components are compared under uniform versus multiple support excitations. To supplement such comparisons, a literature survey is conducted regarding seismic damage to curved bridges, their soil-structure interaction effect, and the multi-support excitation scheme. Moreover, modelling considerations of key components are presented for the A Viaduct, and 6 representative groups of simulated ground motions are selected to capture the effects of site-specific surface topography and soil stratigraphy at the bridge site"--
Author: Andreas J Kappos
Publisher: Springer Science & Business Media
ISBN: 9400739435
Category : Technology & Engineering
Languages : en
Pages : 233
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Book Description
The book focuses on the use of inelastic analysis methods for the seismic assessment and design of bridges, for which the work carried out so far, albeit interesting and useful, is nevertheless clearly less than that for buildings. Although some valuable literature on the subject is currently available, the most advanced inelastic analysis methods that emerged during the last decade are currently found only in the specialised research-oriented literature, such as technical journals and conference proceedings. Hence the key objective of this book is two-fold, first to present all important methods belonging to the aforementioned category in a uniform and sufficient for their understanding and implementation length, and to provide also a critical perspective on them by including selected case-studies wherein more than one methods are applied to a specific bridge and by offering some critical comments on the limitations of the individual methods and on their relative efficiency. The book should be a valuable tool for both researchers and practicing engineers dealing with seismic design and assessment of bridges, by both making the methods and the analytical tools available for their implementation, and by assisting them to select the method that best suits the individual bridge projects that each engineer and/or researcher faces.
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: Bryant G. Nielson
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :
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Book Description
Historical seismic events such as the San Fernando earthquake of 1971 and the Loma Prieta earthquake of 1989 did much to highlight the vulnerabilities in many existing highway bridges. However, it was not until 1990 that this awareness extended to the moderate seismic regions such as the Central and Southeastern United States (CSUS). This relatively long neglect of seismic issues pertaining to bridges in these moderate seismic zones has resulted in a portfolio of existing bridges with seismic deficiencies which must be assessed and addressed. An emerging decision tool, whose use is becoming ever increasingly popular in the assessment of this seismic risk, is that of seismic fragility curves. Fragility curves are conditional probability statements which give the probability of a bridge reaching or exceeding a particular damage level for an earthquake of a given intensity level. As much research has been devoted to the implementation of fragility curves in risk assessment packages, a great need has arisen for bridge fragility curves which are reliable, particularly for those in moderate seismic zones. The purpose of this study is to use analytical methods to generate fragility curves for nine bridge classes which are most common to the CSUS. This is accomplished by first considering the existing bridge inventory and assessing typical characteristics and details from which detailed 3-D analytical models are created. The bridges are subjected to a suite of synthetic ground motions which were developed explicitly for the region. Probabilistic seismic demand models (PSDM) are then generated using these analyses. From these PSD models, fragility curves are generated by considering specific levels of damage which may be of interest. The fragility curves show that the most vulnerable of all the bridge nine bridge classes considered are those utilizing steel girders. Concrete girder bridges appear to be the next most vulnerable followed by single span bridges of all types. Various sources of uncertainty are considered and tracked throughout this study, which allows for their direct implementation into existing seismic risk assessment packages.
Author: Fabio Biondini
Publisher: CRC Press
ISBN: 1000997308
Category : Technology & Engineering
Languages : en
Pages : 6293
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Book Description
Life-Cycle of Structures and Infrastructure Systems contains the lectures and papers presented at IALCCE 2023- The Eighth International Symposium on Life-Cycle Civil Engineering, held at Politecnico di Milano, Milan, Italy, 2-6 July, 2023. This book contains the full papers of 514 contributions presented at IALCCE 2023, including the Fazlur R. Khan Plenary Lecture, nine Keynote Lectures, and 504 technical papers from 45 countries. The papers cover recent advances and cutting-edge research in the field of life-cycle civil engineering, including emerging concepts and innovative applications related to life-cycle design, assessment, inspection, monitoring, repair, maintenance, rehabilitation, and management of structures and infrastructure systems under uncertainty. Major topics covered include life-cycle safety, reliability, risk, resilience and sustainability, life-cycle damaging processes, life-cycle design and assessment, life-cycle inspection and monitoring, life-cycle maintenance and management, life-cycle performance of special structures, life-cycle cost of structures and infrastructure systems, and life-cycle-oriented computational tools, among others. This Open Access Book provides both an up-to-date overview of the field of life-cycle civil engineering and significant contributions to the process of making more rational decisions to mitigate the life-cycle risk and improve the life-cycle reliability, resilience, and sustainability of structures and infrastructure systems exposed to multiple natural and human-made hazards in a changing climate. It will serve as a valuable reference to all concerned with life-cycle of civil engineering systems, including students, researchers, practicioners, consultants, contractors, decision makers, and representatives of managing bodies and public authorities from all branches of civil engineering.
Author: Jeffrey Ger
Publisher: CRC Press
ISBN: 1439837759
Category : Technology & Engineering
Languages : en
Pages : 396
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Book Description
Nonlinear static monotonic (pushover) analysis has become a common practice in performance-based bridge seismic design. The popularity of pushover analysis is due to its ability to identify the failure modes and the design limit states of bridge piers and to provide the progressive collapse sequence of damaged bridges when subjected to major earthq
Author: Bruce M. Douglas
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 96
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Book Description
Author: Mohamed Nabeel Abdel-Salam
Publisher:
ISBN:
Category : Box girder bridges
Languages : en
Pages : 770
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Book Description
