Summary And Comparison Of Multiphase Streambed Scour Analysis At Selected Bridge Sites In Alaska
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Summary And Comparison Of Multiphase Streambed Scour Analysis At Selected Bridge Sites In Alaska
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Author :
language : en
Publisher: DIANE Publishing
Release Date :
Summary And Comparison Of Multiphase Streambed Scour Analysis At Selected Bridge Sites In Alaska written by and has been published by DIANE Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.
Summary And Comparison Of Multiphase Streambed Scour Analysis At Selected Bridge Sites In Alaska
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Author : Jeffrey Scott Conaway
language : en
Publisher:
Release Date : 2004
Summary And Comparison Of Multiphase Streambed Scour Analysis At Selected Bridge Sites In Alaska written by Jeffrey Scott Conaway and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Scour at bridges categories.
Scour At Selected Bridge Sites In Alaska
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Author : Vernon W. Norman
language : en
Publisher:
Release Date : 1975
Scour At Selected Bridge Sites In Alaska written by Vernon W. Norman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1975 with Bridges categories.
Evaluation Of Streambed Scour At Bridges Over Tidal Waterways In Alaska
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Author : Jeffrey Conaway
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2014-07-11
Evaluation Of Streambed Scour At Bridges Over Tidal Waterways In Alaska written by Jeffrey Conaway and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-07-11 with Technology & Engineering categories.
The potential for streambed scour was evaluated at 41 bridges that cross tidal waterways in Alaska. These bridges are subject to several coastal and riverine processes that have the potential, individually or in combination, to induce streambed scour or to damage the structure or adjacent channel. The proximity of a bridge to the ocean and water-surface elevation and velocity data collected over a tidal cycle were criteria used to identify the flow regime at each bridge, whether tidal, riverine, or mixed, that had the greatest potential to induce streambed scour. Water-surface elevations measured through at least one tide cycle at 32 bridges were correlated to water levels at the nearest tide station. Asymmetry of the tidal portion of the hydrograph during the outgoing tide at 12 bridges indicated that riverine flows were stored upstream of the bridge during the tidal exchange. This scenario results in greater discharges and velocities during the outgoing tide compared to those on the incoming tide. Velocity data were collected during outgoing tides at 10 bridges that experienced complete flow reversals, and measured velocities during the outgoing tide exceeded the critical velocity required to initiate sediment transport at three sites. The primary risk for streambed scour at most of the sites considered in this study is from riverine flows rather than tidal fluctuations. A scour evaluation for riverine flow was completed at 35 bridges. Scour from riverine flow was not the primary risk for six tidally-controlled bridges and therefore not evaluated at those sites. Field data including channel cross sections, a discharge measurement, and a water-surface slope were collected at the 35 bridges. Channel instability was identified at 14 bridges where measurable scour and or fill were noted in repeated surveys of channel cross sections at the bridge. Water-surface profiles for the 1-percent annual exceedance probability discharge were calculated by using the Hydrologic Engineering Center's River Analysis System model, and scour depths were calculated using methods recommended by the Federal Highway Administration. Computed contraction-scour depths were greater than 2.0 feet at five bridges and computed pier-scour depths were 4.0 feet or greater at 15 bridges. The potential for streambed scour by both coastal and riverine processes at the bridges considered in this study were evaluated, ranked, and summed to determine a cumulative risk factor for each bridge. Possible factors that could mitigate the scour risks were investigated at 22 bridges that had high individual or cumulative rankings. Mitigating factors such as piers founded in bedrock, deep pier foundations relative to scour depths, and lack of observed scour during field measurements were documented for 13 sites, but additional study and monitoring is needed to better quantify the streambed scour potential for nine sites. Three bridges prone to being affected by storm surges will require more data collection and possibly complex hydrodynamic modeling to accurately quantify the streambed scour potential. Continuous monitoring of water-surface and streambed elevation at one or more piers is needed for two bridges to better understand the tidal and riverine influences on streambed scour.
Evaluation Of Streambed Scour At Bridges Over Tidal Waterways In Alaska
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Author : Jeffrey Scott Conaway
language : en
Publisher: CreateSpace
Release Date : 2012
Evaluation Of Streambed Scour At Bridges Over Tidal Waterways In Alaska written by Jeffrey Scott Conaway and has been published by CreateSpace this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Technology & Engineering categories.
The potential for streambed scour was evaluated at 41 bridges that cross tidal waterways in Alaska. These bridges are subject to several coastal and riverine processes that have the potential, individually or in combination, to induce streambed scour or to damage the structure or adjacent channel. The proximity of a bridge to the ocean and water-surface elevation and velocity data collected over a tidal cycle were criteria used to identify the flow regime at each bridge, whether tidal, riverine, or mixed, that had the greatest potential to induce streambed scour. Water-surface elevations measured through at least one tide cycle at 32 bridges were correlated to water levels at the nearest tide station. Asymmetry of the tidal portion of the hydrograph during the outgoing tide at 12 bridges indicated that riverine flows were stored upstream of the bridge during the tidal exchange. This scenario results in greater discharges and velocities during the outgoing tide compared to those on the incoming tide. Velocity data were collected during outgoing tides at 10 bridges that experienced complete flow reversals, and measured velocities during the outgoing tide exceeded the critical velocity required to initiate sediment transport at three sites. The primary risk for streambed scour at most of the sites considered in this study is from riverine flows rather than tidal fluctuations. A scour evaluation for riverine flow was completed at 35 bridges. Scour from riverine flow was not the primary risk for six tidally-controlled bridges and therefore not evaluated at those sites. Field data including channel cross sections, a discharge measurement, and a water-surface slope were collected at the 35 bridges. Channel instability was identified at 14 bridges where measurable scour and or fill were noted in repeated surveys of channel cross sections at the bridge. Water-surface profiles for the 1-percent annual exceedance probability discharge were calculated by using the Hydrologic Engineering Center's River Analysis System model, and scour depths were calculated using methods recommended by the Federal Highway Administration. Computed contraction-scour depths were greater than 2.0 feet at five bridges and computed pier-scour depths were 4.0 feet or greater at 15 bridges. The potential for streambed scour by both coastal and riverine processes at the bridges considered in this study were evaluated, ranked, and summed to determine a cumulative risk factor for each bridge. Possible factors that could mitigate the scour risks were investigated at 22 bridges that had high individual or cumulative rankings. Mitigating factors such as piers founded in bedrock, deep pier foundations relative to scour depths, and lack of observed scour during field measurements were documented for 13 sites, but additional study and monitoring is needed to better quantify the streambed scour potential for nine sites. Three bridges prone to being affected by storm surges will require more data collection and possibly complex hydrodynamic modeling to accurately quantify the streambed scour potential. Continuous monitoring of water-surface and streambed elevation at one or more piers is needed for two bridges to better understand the tidal and riverine influences on streambed scour.
Streambed Scour Evaluations And Conditions At Selected Bridge Sites In Alaska 2016 17
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Author : Robin A. Beebee
language : en
Publisher:
Release Date : 2019
Streambed Scour Evaluations And Conditions At Selected Bridge Sites In Alaska 2016 17 written by Robin A. Beebee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Bridges categories.
Streambed Scour Evaluations And Conditions At Selected Bridge Sites In Alaska 2012
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Author : Robin A. Beebee
language : en
Publisher:
Release Date : 2015
Streambed Scour Evaluations And Conditions At Selected Bridge Sites In Alaska 2012 written by Robin A. Beebee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Bridges categories.
Monitoring Scour Critical Bridges
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Author : Beatrice E. Hunt
language : en
Publisher: Transportation Research Board
Release Date : 2009
Monitoring Scour Critical Bridges written by Beatrice E. Hunt and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Religion categories.
Evaluation Of Pier Scour Equations For Coarse Bed Streams
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Author : Katherine J. Chase
language : en
Publisher:
Release Date : 2004
Evaluation Of Pier Scour Equations For Coarse Bed Streams written by Katherine J. Chase and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Bridges categories.
Streambed scour at bridge piers is among the leading causes of bridge failure in the United States. Several pier-scour equations have been developed to calculate potential scour depths at existing and proposed bridges. Because many pier-scour equations are based on data from laboratory flumes and from cohesionless silt- and sand-bottomed streams, they tend to overestimate scour for piers in coarse-bed materials. Several equations have been developed to incorporate the mitigating effects of large particle sizes on pier scour, but further investigations are needed to evaluate how accurately pier-scour depths calculated by these equations match measured field data. This report, prepared in cooperation with the Montana Department of Transportation, describes the evaluation of five pier-scour equations for coarse-bed streams. Pier-scour and associated bridge-geometry, bed-material, and streamflow measurement data at bridges over coarse-bed streams in Montana, Alaska, Maryland, Ohio, and Virginia were selected from the Bridge Scour Data Management System. Pier scour calculated using the Simplified Chinese equation, the Froehlich equation, the Froehlich design equation, the HEC-18/Jones equation and the HEC-18/Mueller equation for flood events with approximate recurrence intervals of less than 2 to 100 years were compared to 42 pier-scour measurements. Comparison of results showed that pier-scour depths calculated with the HEC-18/Mueller equation were seldom smaller than measured pier-scour depths. In addition, pier-scour depths calculated using the HEC-18/Mueller equation were closer to measured scour than for the other equations that did not underestimate pier scour. However, more data are needed from coarse-bed streams and from less frequent flood events to further evaluate pier-scour equations.
Evaluation Of Bridge Scour Data At Selected Sites In Ohio
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Author : K. S. Jackson
language : en
Publisher:
Release Date : 1996
Evaluation Of Bridge Scour Data At Selected Sites In Ohio written by K. S. Jackson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Scour at bridges categories.
Scour data collected during 1989-1994 were evaluated to determine whether pier scour and contraction scour occurred at 22 bridge sites in Ohio. Pier-scour depths computed from selected pier-scour prediction equations were compared with measured pier-scour depths, and the accuracy of the prediction equations were evaluated. Observed pier-scour relations were compared to similar relations developed through laboratory research. Mean streambed elevations were evaluated to determine the depth of contraction scour. Channel stability was assessed by use of mean streambed elevations at the approach section. Ground-penetrating radar was used at all sites to investigate the presence of historical scour.