Probabilistic Models and Reliability Analysis of Scour Depth Around Bridge Piers PDF Download
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Author: Laura Christine Bolduc
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Scour at a bridge pier is the formation of a hole around the pier due to the erosion of soil by flowing water; this hole in the soil reduces the carrying capacity of the foundation and the pier. Excessive scour can cause a bridge pier to fail without warning. Current predictions of the depth of the scour hole around a bridge pier are based on deterministic models. This paper considers two alternative deterministic models to predict scour depth. For each deterministic model, a corresponding probabilistic model is constructed using a Bayesian statistical approach and available field and experimental data. The developed probabilistic models account for the estimate bias in the deterministic models and for the model uncertainty. Parameters from both prediction models are compared to determine their accuracy. The developed probabilistic models are used to estimate the probability of exceedance of scour depth around bridge piers. The method is demonstrated on an example bridge pier. The values of the model parameters suggest that the maximum sour depth predicted by the deterministic HEC-18 Sand and HEC-18 Clay models tend to be conservative. Evidence is also found that the applicability of the HEC-18 Clay method is not limited to clay but can also be used for other soil types. The main advantage of the HEC-18 Clay method with respect to the HEC-18 Sand method is that it predicts the depth of scour as a function of time and can be used to estimate the final scour at the end of the design life of a structure. The paper addresses model uncertainties for given hydrologic variables. Hydrologic uncertainties have been presented in a separate paper.
Author: Laura Christine Bolduc
Publisher:
ISBN:
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Languages : en
Pages :
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Book Description
Scour at a bridge pier is the formation of a hole around the pier due to the erosion of soil by flowing water; this hole in the soil reduces the carrying capacity of the foundation and the pier. Excessive scour can cause a bridge pier to fail without warning. Current predictions of the depth of the scour hole around a bridge pier are based on deterministic models. This paper considers two alternative deterministic models to predict scour depth. For each deterministic model, a corresponding probabilistic model is constructed using a Bayesian statistical approach and available field and experimental data. The developed probabilistic models account for the estimate bias in the deterministic models and for the model uncertainty. Parameters from both prediction models are compared to determine their accuracy. The developed probabilistic models are used to estimate the probability of exceedance of scour depth around bridge piers. The method is demonstrated on an example bridge pier. The values of the model parameters suggest that the maximum sour depth predicted by the deterministic HEC-18 Sand and HEC-18 Clay models tend to be conservative. Evidence is also found that the applicability of the HEC-18 Clay method is not limited to clay but can also be used for other soil types. The main advantage of the HEC-18 Clay method with respect to the HEC-18 Sand method is that it predicts the depth of scour as a function of time and can be used to estimate the final scour at the end of the design life of a structure. The paper addresses model uncertainties for given hydrologic variables. Hydrologic uncertainties have been presented in a separate paper.
Author: Peter Frederick Lagasse
Publisher: Transportation Research Board
ISBN: 0309283566
Category : Social Science
Languages : en
Pages : 175
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Book Description
"TRB's National Cooperative Highway Research Program (NCHRP) Report 761: Reference Guide for Applying Risk and Reliability-Based Approaches for Bridge Scour Prediction presents a reference guide designed to help identify and evaluate the uncertainties associated with bridge scour prediction including hydrologic, hydraulic, and model/equation uncertainty. For complex foundation systems and channel conditions, the report includes a step-by-step procedure designed to provide scour factors for site-specific conditions."--Publisher's description.
Author: Paolo Gardoni
Publisher: Springer
ISBN: 3319524259
Category : Technology & Engineering
Languages : en
Pages : 558
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Book Description
This book presents a unique collection of contributions from some of the foremost scholars in the field of risk and reliability analysis. Combining the most advanced analysis techniques with practical applications, it is one of the most comprehensive and up-to-date books available on risk-based engineering. All the fundamental concepts needed to conduct risk and reliability assessments are covered in detail, providing readers with a sound understanding of the field and making the book a powerful tool for students and researchers alike. This book was prepared in honor of Professor Armen Der Kiureghian, one of the fathers of modern risk and reliability analysis.
Author: Michel Ghosn
Publisher: Transportation Research Board
ISBN: 0309087503
Category : Bridges
Languages : en
Pages : 183
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Book Description
Chapter 1. Introduction -- Chapter 2. Reliability models for combinations of extreme events -- Chapter 3. Calibration of load factors for combinations of extreme events -- Chapter 4. Conclusions and future research -- References -- Glossary of notations -- Appendixes.
Author: C.R. Sundararajan
Publisher: Springer Science & Business Media
ISBN: 1461517710
Category : Technology & Engineering
Languages : en
Pages : 756
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Book Description
The need for a comprehensive book on probabilistic structural mechanics that brings together the many analytical and computational methods developed over the years and their applications in a wide spectrum of industries-from residential buildings to nuclear power plants, from bridges to pressure vessels, from steel structures to ceramic structures-became evident from the many discussions the editor had with practising engineers, researchers and professors. Because no single individual has the expertise to write a book with such a di.verse scope, a group of 39 authors from universities, research laboratories, and industries from six countries in three continents was invited to write 30 chapters covering the various aspects of probabilistic structural mechanics. The editor and the authors believe that this handbook will serve as a reference text to practicing engineers, teachers, students and researchers. It may also be used as a textbook for graduate-level courses in probabilistic structural mechanics. The editor wishes to thank the chapter authors for their contributions. This handbook would not have been a reality without their collaboration.
Author: John Junke Guo
Publisher: World Scientific
ISBN: 981448797X
Category : Technology
Languages : en
Pages : 1152
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Book Description
This book presents a wide range of recent advances in hydraulics and water engineering. It contains four sections: hydraulics and open channel flow; hydrology, water resources management and hydroinformatics; maritime hydraulics; ecohydraulics and water quality management. World authorities such as Mike Abbot, I Nezu, A J Metha, M Garcia and P Y Julien have contributed to the book.
Author: Seifedine Kadry
Publisher: Springer
ISBN: 331907167X
Category : Science
Languages : en
Pages : 807
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Book Description
This book offers unique insight on structural safety and reliability by combining computational methods that address multiphysics problems, involving multiple equations describing different physical phenomena and multiscale problems, involving discrete sub-problems that together describe important aspects of a system at multiple scales. The book examines a range of engineering domains and problems using dynamic analysis, nonlinear methods, error estimation, finite element analysis and other computational techniques. This book also: · Introduces novel numerical methods · Illustrates new practical applications · Examines recent engineering applications · Presents up-to-date theoretical results · Offers perspective relevant to a wide audience, including teaching faculty/graduate students, researchers and practicing engineers.
Author: Congpu Yao
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Bridge scour is the loss of soil by erosion due to water flowing around bridge supports. Scour has been the number one cause of bridge collapse in the United States with an average rate of 22 bridges collapsing each year. This dissertation addresses three topics related to bridge scour. First, three sets of databases are used to quantify the statistical parameters associated with the scatter between the predicted and measured scour depth as well as the probability that a deterministically predicted scour depth will be exceeded. The analysis results from these databases will also be used to provide the bias factors in the scour depth predictions in practice. In the second part of the dissertation, these statistical parameters are used to develop a reliability-based Load and Resistance Factor Design (LRFD) for shallow and deep foundations subjected to scour. The goal is to provide a design procedure for the bridge foundations, where the reliability of the foundation is the same with or without scour. For shallow foundations, the key of the design issue is the location of the foundation depth and the probability that the scour depth will exceed the foundation depth. Therefore, for shallow foundations, the proposed LRFD calibration is based on the probability of exceedance of the predicted scour depth. However for deep foundations, the key of the design issue is the resistance factor associated with the axial capacity of a pile. Hence, the proposed LRFD calibration for deep foundations is based on a reliability analysis using First-Order Reliability Method (FORM). The dissertation is broadened in the third part by analyzing he risk associated with bridge scour, where the risk is defined as the probability of failure times the value of the consequences. In the third part, the risk associated with bridge scour is compared to risks associated with other engineering structures as well. Target values of acceptable risk are recommended as part of the conclusions. The outcome of the research will modify the current "AASHTO LRFD Bridge Design Specifications" developed by the American Association of State Highway and Transportation Officials (AASHTO) and help the practitioners design foundations of bridges over rivers for a uniform probability of failure in the case of scour. The risk of bridge scour is also quantified in the dissertation, and compared with common societal risks and civil engineering risks. It will help engineers understand the risk level associated with bridge scour. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149453
Author: Paolo Gardoni
Publisher: Routledge
ISBN: 135139276X
Category : Business & Economics
Languages : en
Pages : 1134
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Book Description
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.
Author: Mehrdad Nazariha
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
An investigation of local scour at pier groups has been conducted with the aim of developing design recommendations and scour depth prediction equations for the bridge pier groups. A comprehensive series of steady uniform flow experiments was performed on groups of 2, 3, 4, and 6 model piers. All tests were conducted under clear-water scour conditions. Parameters governing local scour depth around bridge piers include: flow characteristics, sediment properties, and pier size and shape. The effects of these parameters on the maximum local scour depth for a single pier (D$\sb{\rm s}$), have been thoroughly investigated in the past. However, when design criteria developed for single piers are applied directly to pier groups, this approach ignores the following important group effects: (1) sheltering, (2) reinforcement, and (3) horse-shoe vortex (HSV) compression. Furthermore, the group effects will alter with changes in pier spacing, S, and flow angle of attack, $\beta$. This study, which investigates the local scouring process for the aforementioned groups of model bridge piers, and presents design relationships for predicting the corresponding maximum local scour depths, is an attempt to address this limitation in current design practice. Initially the local scour was examined for five different single pier diameters (0.0127 m, 0.018 m, 0.025 m, 0.033 m and 0.05 m). Having established single pier relationships, groups of 2, 3, 4, and 6 equally spaced piers were examined, while altering alignment to the flow and separation distances. For piers in line with the flow direction, downstream piers are sheltered by the upstream ones resulting in reducing scour depth around downstream piers. This effect diminishes with the increasing $\beta$ if there is only one row of piers i.e., 2 and 3 pier groups. In the case of 2 rows of piers aligned to the flow direction (i.e., 4- and 6-pier groups), there is a specific range of $\beta$ in which downstream piers are exposed to the flow. As $\beta$ increases, depending on pier spacing, the piers of one row may shelter the downstream piers of the other row. The reinforcement effect is significant only for small ratios of pier spacing/ pier diameter (S/d) when $\beta \le$ 10$\sp0$. In these ranges of S/d and $\beta$, the front piers are scoured more than that of a single pier. Moreover, the score depth of downstream piers, which are less than that of a single pier, increases with increasing S/d. The compressed (HSV) arms affect the local scour depth significantly if piers are staggered and S/d $\le$ 5. In this range of S/d, the HSV arms are intensified, resulting in a deeper scour hole. However, this effect also becomes insignificant with increasing S/d. The data obtained for each pier group were analysed, using a multiple regression model, to develop local scour depth prediction equations for the front, middle, and rear piers. The regression model includes two important dimensionless parameters ($\beta$ and S/d) associated with group effects, as regressors. The proposed prediction equations estimated the observed data and similar-type published data reasonably well, within marginal errors. From a general practical view-point, the number of prediction equations was reduced to two equations for all pier groups: one for the front piers and the second one for the downstream piers (i.e. combined middle and rear piers).
