Download or read book Field Observations and Evaluations of Streambed Scour at Bridges written by U. S. Department Of Transportation and published by CreateSpace. This book was released on 2015-03-12 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridge piers and highway embankments leading to a bridge often obstruct the flow of floodwaters, causing an increase in velocity and the development of vortices. The increased velocity and vortices often cause scour near the bridge foundations. The damage to and failure of bridges caused by scour are problems of national concern. This report describes the results of the second USGS national field-data collection and analysis study on scour at bridges, funded by FHWA. The database originally developed during the first national study has been enhanced and many scour measurements added, including measurements of abutment and contraction scour. Sufficient local pier scour data are now available to permit a detailed analysis of local pier scour. Scour depths computed from published pier scour equations are compared to the field measurements. Many commonly cited dimensionless variables believed to control the depth of scour are evaluated and compared with equations developed from laboratory data. The effect of the size and gradation of the bed material on the depth of scour is investigated, and a correction factor for the HEC-18 pier scour equation is proposed. Available data are insufficient to permit a detailed investigation of contraction and abutment scour; however, some basic comparisons and qualitative observations are presented on the basis of a review of the literature. The results of scour analyses for two contracted bridges are compared with real-time field data.
Download or read book Field Observations and Evaluations of Streambed Scour at Bridges written by David S. Mueller and published by . This book was released on 2005 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Field Observations and Evaluations of Streambed Scour at Bridges written by and published by . This book was released on 2005 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: The variability and complexity of site conditions make it difficult to develop methodology for predicting scour at bridges. Laboratory investigations often oversimplify or ignore many complexities common in the field. The U.S. Geological Survey, in cooperation with the Federal Highway Administration and many State highway agencies, has collected and compiled field data on scour at bridges at 79 sites located in 17 States. These data have been analyzed to isolate pier scour, contraction scour, and abutment scour. The national data base contains 493 local pier scour measurements, 18 contraction scour measurements, and 12 abutment scour measurements. The pier scour measurements were used to evaluate 26 published pier scour equations.
Download or read book Evaluation of Streambed Scour at Bridges Over Tidal Waterways in Alaska written by Jeffrey Conaway and published by Createspace Independent Publishing Platform. This book was released on 2014-07-11 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Evaluation of Streambed Scour at Bridges Over Tidal Waterways in Alaska written by Jeffrey Scott Conaway and published by CreateSpace. This book was released on 2012 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Evaluation of Bridge scour Data at Selected Sites in Ohio written by K. S. Jackson and published by . This book was released on 1996 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Bridge Scour Evaluation written by John Kattell and published by . This book was released on 1998 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Method for Rapid Estimation of Scour at Highway Bridges Based on Limited Site Data written by Steven R. Holnbeck and published by . This book was released on 1997 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Streambed Scour at Bridges in Indiana written by Gary Bennett and published by . This book was released on 1997 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stream Instability Bridge Scour and Countermeasures A Field Guide for Bridge Inspectors written by Transportation Dept., Federal Highway Administration and published by Government Printing Office. This book was released on with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: FHWA Publication No. FHWA-NHI-08-0106. February 2009. Explains the behavior of rivers in order to recognize changing conditions associated with unstable streams or scour at bridge foundations that may threaten the stability of the bridge. Provides tips and guidance on what to look for with regard to both stream instability, including lateral instability, degradation, and aggradation, and scour at bridges, including contraction scour, pier scour, and abutment scour. Also covered are plans of action and countermeasures, such as monitoring, flood watches, bridge closures, and river training countermeasures.
Download or read book Evaluating Scour at Bridges written by E. V. Richardson and published by . This book was released on 1991 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document, Hydraulic Engineering Circular No. 18 (HEC-18), contains the state-of-knowledge and practice for dealing with scour at highway bridges. The procedures for designing new, replacement and rehabilitated bridges to resist scour are presented. Procedures are presented for evaluating the scour vulnerability of existing bridges as well as inspecting bridges for scour. The use of countermeasures to protect bridges evaluated as failure prone due to scour is also presented. This document replaces the Federal Highway Administration (FHWA) publication "Interim Procedures for Evaluating Scour at Bridges," which was issued with FHWA Technical Advisory 5140.20, "Scour at Bridges," in September 1988.
Download or read book National Bridge Scour Program measuring Scour of the Streambed at Highway Bridges written by David S. Mueller and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development Verification and Application of a Simplified Method to Estimate Total streambed Scour at Bridge Sites in Illinois written by Robert R. Holmes and published by . This book was released on 1996 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluating Scour at Bridges written by and published by . This book was released on 1995 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document is the third of HEC 18, i.e., presents the state of knowledge and practice for the design, evaluation, and inspection of bridges for scour. It contains updated material not included in the second edition dated April 1993. This document is a revision to HEC 18 dated April 1993 which, in turn, was an update of HEC 18 dated Feburary 1991 and of the publication, "Interim Procedures for Evaluating Scour at Bridges," issued in September 1988 as part of the FHWA Technical Advisory T 5140.20, "Scour at Bridges." T 5140.20 has since been superseded by T 5410.23, "Evaluating Scour at Bridges" dated October 28,1991. This document contains revisions obtained from further scour-related developments and use of the 1993 edition of HEC 18 by the highway community
Download or read book Stream Stability and Scour at Highway Bridges written by Everett V. Richardson and published by ASCE Publications. This book was released on 1999-01-01 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sponsored by the Water Resources Engineering (Hydraulics) Divsion of ASCE. This collection contains 75 papers and 321 abstracts presented at conferences sponsored by the Water Resources Engineering (Hydraulics) Division of ASCE from 1991 through 1998. The collection contains many new and expanded versions of the original papers and is designed to assist the practitioner with the concepts in evaluating stream instability and scour at bridges. Topics include: history of bridge scour research; bridge scour determination; stream stability and geomorphology; construction scour; instrumentation for measuring and monitoring; field measurement; computer and physical modeling of bridge scour; scour at culverts; and economic and risk analysis. One important paper contains 384 field measurements of local scour at piers made by the U.S. Geological Survey.
Download or read book Localized Scour at Bridge Piers on Graded Particle Streambeds written by Howard D. Copp and published by . This book was released on 1991 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document reports on results of research to develop a method for estimating depth of local scour at bridge piers that would provide an improved estimate from current methodology, i.e., one (or more) based on sand bed streams.
Download or read book Reference Guide for Applying Risk and Reliability Based Approaches for Bridge Scour Prediction written by Peter Frederick Lagasse and published by Transportation Research Board. This book was released on 2013 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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.
