The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Dan M Frangopol - One of the best experts on this subject based on the ideXlab platform.
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improved assessment of mass Concrete Dams using acoustic travel time tomography part ii application
Construction and Building Materials, 2000Co-Authors: William F Kepler, Leonard J Bond, Dan M FrangopolAbstract:Abstract The aging of key elements of our civil infrastructure, including Dams, is presenting new challenges for the development of methodology that will adequately predict remaining safe life, and identify those structures where remedial action is required. To meet this need, a new approach for non-destructive testing of large Concrete Dams has been developed. It combines aspects of ultrasonic non-destructive testing and seismic surveying in a new methodology ‘Acoustic Travel Time Tomography’ (ATTT). This is the second part of an investigation on improved assessment of mass Concrete Dams using ATTT. A companion paper [Bond LJ, Kepler WF, Frangopol, DM. Improved assessment of mass Concrete Dams using acoustic travel time tomography. Part I — Theory. Constr Build Mater 2000 Vol. 14, No. 3, pp. 133–146] focused on the background of the physics of ATTT. ATTT was tested in the laboratory, modified for large-scale testing, then evaluated for reliability. This study reports the application of the methodology, instrumentation, and data analysis techniques developed during the study. The research demonstrates that ATTT can locate and characterize cracks, voids and other anomalies deep within a mass Concrete dam. The results at each stage of the study have shown that ATTT is a potentially highly accurate testing procedure, and that it is uniquely suited to the evaluation of large Concrete Dams.
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improved assessment of mass Concrete Dams using acoustic travel time tomography part i theory
Construction and Building Materials, 2000Co-Authors: Leonard J Bond, William F Kepler, Dan M FrangopolAbstract:Abstract This is the first part of an investigation on improved assessment of mass Concrete Dams using Acoustic Travel Time Tomography (ATTT). It presents the concept and basic science for ATTT. ATTT combines aspects of ultrasonic measurements previously used for material characterization, ultrasonic methods applied to test Concrete and features of methods used in shallow seismic surveys. This science/technology is integrated into a system that records travel time data and applies tomography software. The resulting tomographs have the potential to provide cross-sectional images of the structure that can be used to locate cracks, identify regions of structural damage, and other anomalies deep inside a massive Concrete structure. Results from initial laboratory and field studies obtained with a system that embodies the approach presented in this paper and which provides proof-of-concept data, are presented in a companion paper (Kepler WF, Bond LJ, Frangopol DM. Improved assessment of mass Concrete Dams using acoustic travel time tomography. Part II — applications. Constr Build Mater, 2000; vol. 14, No. 3, pp. 147–156).
Leonard J Bond - One of the best experts on this subject based on the ideXlab platform.
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improved assessment of mass Concrete Dams using acoustic travel time tomography part ii application
Construction and Building Materials, 2000Co-Authors: William F Kepler, Leonard J Bond, Dan M FrangopolAbstract:Abstract The aging of key elements of our civil infrastructure, including Dams, is presenting new challenges for the development of methodology that will adequately predict remaining safe life, and identify those structures where remedial action is required. To meet this need, a new approach for non-destructive testing of large Concrete Dams has been developed. It combines aspects of ultrasonic non-destructive testing and seismic surveying in a new methodology ‘Acoustic Travel Time Tomography’ (ATTT). This is the second part of an investigation on improved assessment of mass Concrete Dams using ATTT. A companion paper [Bond LJ, Kepler WF, Frangopol, DM. Improved assessment of mass Concrete Dams using acoustic travel time tomography. Part I — Theory. Constr Build Mater 2000 Vol. 14, No. 3, pp. 133–146] focused on the background of the physics of ATTT. ATTT was tested in the laboratory, modified for large-scale testing, then evaluated for reliability. This study reports the application of the methodology, instrumentation, and data analysis techniques developed during the study. The research demonstrates that ATTT can locate and characterize cracks, voids and other anomalies deep within a mass Concrete dam. The results at each stage of the study have shown that ATTT is a potentially highly accurate testing procedure, and that it is uniquely suited to the evaluation of large Concrete Dams.
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improved assessment of mass Concrete Dams using acoustic travel time tomography part i theory
Construction and Building Materials, 2000Co-Authors: Leonard J Bond, William F Kepler, Dan M FrangopolAbstract:Abstract This is the first part of an investigation on improved assessment of mass Concrete Dams using Acoustic Travel Time Tomography (ATTT). It presents the concept and basic science for ATTT. ATTT combines aspects of ultrasonic measurements previously used for material characterization, ultrasonic methods applied to test Concrete and features of methods used in shallow seismic surveys. This science/technology is integrated into a system that records travel time data and applies tomography software. The resulting tomographs have the potential to provide cross-sectional images of the structure that can be used to locate cracks, identify regions of structural damage, and other anomalies deep inside a massive Concrete structure. Results from initial laboratory and field studies obtained with a system that embodies the approach presented in this paper and which provides proof-of-concept data, are presented in a companion paper (Kepler WF, Bond LJ, Frangopol DM. Improved assessment of mass Concrete Dams using acoustic travel time tomography. Part II — applications. Constr Build Mater, 2000; vol. 14, No. 3, pp. 147–156).
William F Kepler - One of the best experts on this subject based on the ideXlab platform.
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improved assessment of mass Concrete Dams using acoustic travel time tomography part ii application
Construction and Building Materials, 2000Co-Authors: William F Kepler, Leonard J Bond, Dan M FrangopolAbstract:Abstract The aging of key elements of our civil infrastructure, including Dams, is presenting new challenges for the development of methodology that will adequately predict remaining safe life, and identify those structures where remedial action is required. To meet this need, a new approach for non-destructive testing of large Concrete Dams has been developed. It combines aspects of ultrasonic non-destructive testing and seismic surveying in a new methodology ‘Acoustic Travel Time Tomography’ (ATTT). This is the second part of an investigation on improved assessment of mass Concrete Dams using ATTT. A companion paper [Bond LJ, Kepler WF, Frangopol, DM. Improved assessment of mass Concrete Dams using acoustic travel time tomography. Part I — Theory. Constr Build Mater 2000 Vol. 14, No. 3, pp. 133–146] focused on the background of the physics of ATTT. ATTT was tested in the laboratory, modified for large-scale testing, then evaluated for reliability. This study reports the application of the methodology, instrumentation, and data analysis techniques developed during the study. The research demonstrates that ATTT can locate and characterize cracks, voids and other anomalies deep within a mass Concrete dam. The results at each stage of the study have shown that ATTT is a potentially highly accurate testing procedure, and that it is uniquely suited to the evaluation of large Concrete Dams.
-
improved assessment of mass Concrete Dams using acoustic travel time tomography part i theory
Construction and Building Materials, 2000Co-Authors: Leonard J Bond, William F Kepler, Dan M FrangopolAbstract:Abstract This is the first part of an investigation on improved assessment of mass Concrete Dams using Acoustic Travel Time Tomography (ATTT). It presents the concept and basic science for ATTT. ATTT combines aspects of ultrasonic measurements previously used for material characterization, ultrasonic methods applied to test Concrete and features of methods used in shallow seismic surveys. This science/technology is integrated into a system that records travel time data and applies tomography software. The resulting tomographs have the potential to provide cross-sectional images of the structure that can be used to locate cracks, identify regions of structural damage, and other anomalies deep inside a massive Concrete structure. Results from initial laboratory and field studies obtained with a system that embodies the approach presented in this paper and which provides proof-of-concept data, are presented in a companion paper (Kepler WF, Bond LJ, Frangopol DM. Improved assessment of mass Concrete Dams using acoustic travel time tomography. Part II — applications. Constr Build Mater, 2000; vol. 14, No. 3, pp. 147–156).
Victor E Saouma - One of the best experts on this subject based on the ideXlab platform.
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stochastic analysis of Concrete Dams with alkali aggregate reaction
Cement and Concrete Research, 2020Co-Authors: Victor E Saouma, M A Haririardebili, Lori GrahambradyAbstract:Abstract Following a comprehensive literature survey, this paper will first address the theoretical underpinnings of stochastic modeling. An algorithm to model arch dam inhomogeneity in terms of characteristic length is presented next and is applied to assess the impact of Concrete's elastic modulus and volumetric AAR expansion. Results are contrasted with both a single deterministic analysis, and a series of classical Monte Carlo simulations in which non-Gaussian stochastically varying properties are used. The impact of randomness in material properties on displacements, joint openings, and stresses are investigated. It is found that whereas mean values of these responses are for the most part little impacted, standard deviations exhibit a greater variation vis a vis simple Monte Carlo simulations. Furthermore, the safety is assessed through fragility surfaces, and meta-modeling. This study determined that whereas randomness may affect local results e.g. stresses, their impact may be neglected for globally averaged responses e.g. displacements.
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single and multi hazard capacity functions for Concrete Dams
Soil Dynamics and Earthquake Engineering, 2017Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:Abstract In the context of performance-based engineering (PBE), it is essential to determine a functional relationship for the response in terms of externally (such as hydraulic or seismic) or internally (such as alkali silica reaction)-imposed stressors. The importance of nonlinear analyses for each of the critical load cases (or stressors) or combinations thereof, as well as the final safety assessment are discussed. This extensive survey paper reviews an extensive body of literature in multiple disciplines. This article aims to present all relevant methods (specially those not tailored for Dams) in a more palpable way to dam engineers. Finally as a result of this extensive study new multi hazard capacity functions are introduced.
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seismic fragility analysis of Concrete Dams a state of the art review
Engineering Structures, 2016Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:Abstract Given the recent impetus for probabilistic based analyses of Dams, and the limited previous attempts to address this timely question, there is a need for a comprehensive assessment of the disparate previous work. Hence, this paper provides a comprehensive and comparative review of major (over twenty) publications addressing seismic fragility analyses of Concrete Dams. First, fundamental concepts are reviewed and clarified to facilitate comprehension of the later part. Then, papers are individually scrutinized, key figures redrawn to provide a uniform basis for comparison. When deemed necessary, additional clarifications and cross referencing with equations in the first part are provided. Next, tables summarizing the various methods are presented, on the basis of which the authors provide a set of minimum requirements for seismic fragility curve/surface development. It is noted that the vast majority of the papers still relied on linear analyses with simplified limit states. On the other hands few papers pursued a nonlinear approach and addressed the collapse mechanism and/or hybrid limit state definitions. Finally, the contextual framework within which fragility curves are used is presented within the scope of a performance based earthquake engineering analysis of a Concrete dam.
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collapse fragility curves for Concrete Dams comprehensive study
Journal of Structural Engineering-asce, 2016Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:AbstractThis paper explores the seismic fragility curves for gravity Dams with or without ground motion vertical component within the context of performance-based earthquake engineering. Structural analyses are performed using multiple-record incremental dynamic ones. The resulting capacity curves are contrasted with the well-established ones of framed structures. An optimal intensity measure parameter is also selected among 37 variations, and it is determined that the combined spectral acceleration leads to lowest dispersion. Finally, the derived fragility curves using the scaled records are compared with those from probabilistic seismic demand analysis (unscaled records). Results show acceptable consistency between the two methods. In addition, the effect of accounting for the epistemic uncertainty and pool elevation are discussed and are found to respectively alter the dispersion and median value of the collapse fragility curves.
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probabilistic seismic demand model and optimal intensity measure for Concrete Dams
Structural Safety, 2016Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:Abstract This paper addresses the probabilistic seismic demand model (PSDM) which is the relationship between the intensity measure (IM) (such as spectral acceleration) and the engineering demand parameter (EDP) (such as displacement and crack ratio – ratio of crack length to total crack path). It expresses the probability that a system experiences a certain level of demand for a given IM level. Formulation is for a Concrete gravity dam. First, IMs are categorized and the criteria for the selection of an optimal one presented. Then, cloud analysis is performed where the structure is subjected to a large set of un-scaled ground motions and the maximum responses are extracted for each one and plotted as a cloud of results. This methodology is applied to Pine Flat gravity dam. Model is first presented followed by results and conclusions. When the results of the cloud analysis are aggregated, then one can plot the seismic fragility curve which is the probability of EDP exceedance in terms of the IM parameter.
M A Haririardebili - One of the best experts on this subject based on the ideXlab platform.
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stochastic analysis of Concrete Dams with alkali aggregate reaction
Cement and Concrete Research, 2020Co-Authors: Victor E Saouma, M A Haririardebili, Lori GrahambradyAbstract:Abstract Following a comprehensive literature survey, this paper will first address the theoretical underpinnings of stochastic modeling. An algorithm to model arch dam inhomogeneity in terms of characteristic length is presented next and is applied to assess the impact of Concrete's elastic modulus and volumetric AAR expansion. Results are contrasted with both a single deterministic analysis, and a series of classical Monte Carlo simulations in which non-Gaussian stochastically varying properties are used. The impact of randomness in material properties on displacements, joint openings, and stresses are investigated. It is found that whereas mean values of these responses are for the most part little impacted, standard deviations exhibit a greater variation vis a vis simple Monte Carlo simulations. Furthermore, the safety is assessed through fragility surfaces, and meta-modeling. This study determined that whereas randomness may affect local results e.g. stresses, their impact may be neglected for globally averaged responses e.g. displacements.
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support vector machine based reliability analysis of Concrete Dams
Soil Dynamics and Earthquake Engineering, 2018Co-Authors: M A Haririardebili, Farhad PourkamalianarakiAbstract:This paper presents possible combination of structural responses of Concrete Dams with machine learning techniques. Support vector machine (SVM) method is adopted and two broad applications are presented: one for a simplified flood reliability assessment of gravity Dams and the other for detailed nonlinear seismic finite element method (FEM) based analysis. Up to seventeen random variables are considered in the former example and the results of SVM contrasted with classical reliability analyses techniques (i.e., first- and second-order reliability methods, Monte Carlo simulation, Latin Hypercube and importance sampling techniques). For the latter example, a FEM-SVM based hybrid methodology is proposed for reduction of number of nonlinear analyses. A discussion is provided on the relation between the optimal earthquake intensity measures, the damage states and the accuracy of prediction. It is found that the family of SVM (i.e. standard, least squares, multi-class and regression) is an useful and effective tool for classification, response prediction and reliability analysis of the Concrete Dams with reasonable accuracy.
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single and multi hazard capacity functions for Concrete Dams
Soil Dynamics and Earthquake Engineering, 2017Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:Abstract In the context of performance-based engineering (PBE), it is essential to determine a functional relationship for the response in terms of externally (such as hydraulic or seismic) or internally (such as alkali silica reaction)-imposed stressors. The importance of nonlinear analyses for each of the critical load cases (or stressors) or combinations thereof, as well as the final safety assessment are discussed. This extensive survey paper reviews an extensive body of literature in multiple disciplines. This article aims to present all relevant methods (specially those not tailored for Dams) in a more palpable way to dam engineers. Finally as a result of this extensive study new multi hazard capacity functions are introduced.
-
seismic fragility analysis of Concrete Dams a state of the art review
Engineering Structures, 2016Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:Abstract Given the recent impetus for probabilistic based analyses of Dams, and the limited previous attempts to address this timely question, there is a need for a comprehensive assessment of the disparate previous work. Hence, this paper provides a comprehensive and comparative review of major (over twenty) publications addressing seismic fragility analyses of Concrete Dams. First, fundamental concepts are reviewed and clarified to facilitate comprehension of the later part. Then, papers are individually scrutinized, key figures redrawn to provide a uniform basis for comparison. When deemed necessary, additional clarifications and cross referencing with equations in the first part are provided. Next, tables summarizing the various methods are presented, on the basis of which the authors provide a set of minimum requirements for seismic fragility curve/surface development. It is noted that the vast majority of the papers still relied on linear analyses with simplified limit states. On the other hands few papers pursued a nonlinear approach and addressed the collapse mechanism and/or hybrid limit state definitions. Finally, the contextual framework within which fragility curves are used is presented within the scope of a performance based earthquake engineering analysis of a Concrete dam.
-
collapse fragility curves for Concrete Dams comprehensive study
Journal of Structural Engineering-asce, 2016Co-Authors: M A Haririardebili, Victor E SaoumaAbstract:AbstractThis paper explores the seismic fragility curves for gravity Dams with or without ground motion vertical component within the context of performance-based earthquake engineering. Structural analyses are performed using multiple-record incremental dynamic ones. The resulting capacity curves are contrasted with the well-established ones of framed structures. An optimal intensity measure parameter is also selected among 37 variations, and it is determined that the combined spectral acceleration leads to lowest dispersion. Finally, the derived fragility curves using the scaled records are compared with those from probabilistic seismic demand analysis (unscaled records). Results show acceptable consistency between the two methods. In addition, the effect of accounting for the epistemic uncertainty and pool elevation are discussed and are found to respectively alter the dispersion and median value of the collapse fragility curves.