Scour At Bridge Foundations

"This report provides a methodology for estimating the time rate of scour and the design scour depth for a bridge founded on rock, as well as design and construction guidelines for application of the methodology. It will be of interest to hydraulic, bridge, and geotechnical engineers responsible for designing bridge foundations on rock or maintenance engineers concerned about existing bridges founded on erodible rock."--Foreword.

"A comprehensive state-of-the-art treatment of scour and bridge foundations - both a handy reference text and a manual for the practicing bridge designer."--Publisher.

Publisher's Note: Products purchased from Third Party sellers are not guaranteed by the publisher for quality, authenticity, or access to any online entitlements included with the product. Proven methods for preventing and mitigating bridge and highway flood scour Offering detailed guidelines on bridge scour countermeasures, this comprehensive resource provides a proactive strategy for the design and construction of bridges to prevent scour, as well as a reactive plan for post-flood disaster management. Topics discussed include erosion, causes of scour, AASHTO design codes, hydrology, hydraulics, scour analysis, inspection methods, and modern materials technology. Real-world case studies illustrate the concepts presented. The authoritative information in this practical guide will help you to develop more efficient and cost-effective design processes and bridge management systems for river bridges subjected to floods. Flood Scour for Bridges and Highways covers: Floods, scour problems, and mitigation River instability caused by flow obstructions Past failures and bridges vulnerable to failure Geotechnical and hydraulic issues at scour-critical rivers and bridges Hydrology, floods, and scour-critical bridges Estimating scour depths and selecting applicable countermeasures Inspections, ratings, and monitoring countermeasures FHWA, HEC-18, and HEC-23 scour countermeasures as remediation Innovative methods of flood control and disaster management

The most common cause of bridge failures is from floods scouring bed material from around bridge foundations. Scour is the engineering term for the erosion caused by water of the soil surrounding a bridge foundation (piers and abutments). The purpose of this document is to provide guidelines for the following: 1. Designing new and replacement bridges to resist scour, 2. Evaluating existing bridges for vulnerability to scour, 3. Inspecting bridges for scour, 4. Improving the state-of-practice of estimating scour at bridges. This document is the fifth edition of HEC-18. It presents the state of knowledge and practice for the design, evaluation and inspection of bridges for scour. There are two companion documents, HEC-20 entitled "Stream Stability at Highway Structures," and HEC-23 entitled "Bridge Scour and Stream Instability Countermeasures." These three documents contain updated material from previous editions and continued research by NCHRP, FHWA, State DOTs, and universities. This fifth edition of HEC-18 also contains revisions obtained from further scour-related developments and the use of the 2001 edition by the highway community. The major changes in the fifth edition of HEC-18 are: expanded discussion on the policy and regulatory basis for the FHWA Scour Program, including risk-based approaches for evaluations, developing Plans of Action (POAs) for scour critical bridges, and expanded discussion on countermeasure design philosophy (new vs. existing bridges). This fifth edition includes: a new section on contraction scour in cohesive materials, an updated abutment scour section, alternative abutment design approaches, alternative procedures for estimating pier scour, and new guidance on pier scour with debris loading. There is a new chapter on soils, rock and geotechnical considerations related to scour. Additional changes include: a new approach for pier scour in coarse material, new sections on pier scour in cohesive materials and pier scour in erodible rock, revised guidance for vertical contraction scour (pressure flow) conditions, guidance for predicting scour at bottomless culverts, deletion of the "General Scour" term, and revised discussion on scour at tidal bridges to reflect material now covered in HEC-25 (2nd Edition).

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.

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

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.