This report describes a laboratory study of abutment scour for compound channels where the experiments simulated floodplains with defined channel and overbank flow areas at different elevations. A new abutment scour prediction equation was derived as part of this study and is presented in an appendix of the fourth edition of the Federal Highway Administration Hydraulic Engineering Circular No. 18 (HEC-18). This report will be of interest to bridge engineers and hydraulic engineers involved in bridge scour evaluations and to researchers involved in developing improved bridge scour evaluation procedures. It is being published as a Web document only.
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the contents or the use thereof. This report does not constitute a standard, specification, or regulation.
The U.S. Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein only because they are considered essential to the objective of this document.
T. Paul Teng, P.E.
Director, Office of Infrastructure
Research and Development
1. Report No. FHWA-RD-99-156 |
2. Government Accession No. |
3. Recipient's Catalog No. |
4. Title and Subtitle Enhanced Abutment Scour Studies For Compound Channels |
5. Report Date August 2004 |
6. Performing Organization Code |
7. Author(s) Terry W. Sturm |
8. Performing Organization Report No. |
9. Performing Organization Name and Address Georgia Institute of Technology School of Civil and Environmental Engineering Atlanta, GA 30332 |
10. Work Unit No. (TRAIS) |
11. Contract or Grant No. DTFH61-02-C-00007 |
12. Sponsoring Agency Name and Address Office of Infrastructure Research and Development Federal Highway Administration 6300 Georgetown Pike McLean, VA 22101-2296 |
13. Type of Report and Period Covered Final Report 1994-1999 |
14. Sponsoring Agency Code |
15. Supplementary Notes Contracting Officer's Technical Representative (COTR): J. Sterling Jones, HRDI-07 |
16. Abstract Experimental results and analyses are given in this report on bridge abutment scour in compound channels. Experiments were conducted in a laboratory flume with a cross section consisting of a wide floodplain adjacent to a main channel. The embankment length, discharge, sediment size, and abutment shape were varied, and the resulting equilibrium scour depths were measured. Water-surface profiles, velocities, and scour-hole contours were also measured. In the report, a methodology is developed for estimating abutment scour that takes into account the redistribution of discharge in the bridge contraction, abutment shape, sediment size, and tailwater depth. The independent variables in the proposed scour formula are evaluated at the approach-channel cross section and can be obtained from a one-dimensional water-surface profile computer program such as the Water-Surface Profile Program (WSPRO). The proposed scour evaluation procedure is outlined and ilustrated, including consideration of the time required to reach equilibrium scour. The proposed methodology is applied to two cases of measured scour in the field. |
17. Key Words Bridge scour, abutment scour, compound channels. |
18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161. |
19. Security Classif. (of this report) Unclassified |
20. Security Classif. (of this page) Unclassified |
21. No. of Pages 144 |
22. Price |