Repository logo
 

Pressure flow effects on scour at bridges

Simple item page
dc.contributor.authorRobeson, Michael D., author
dc.contributor.authorThornton, Christopher I., advisor
dc.contributor.authorAbt, Steven R., committee member
dc.contributor.authorArneson, Larry A., committee member
dc.contributor.authorDoe, William W., committee member
dc.date.accessioned2007-01-03T04:32:49Z
dc.date.available2007-01-03T04:32:49Z
dc.date.issued2000
dc.descriptionDepartment Head: Marvin E. Criswell.
dc.description.abstractScour caused by the occurrence of pressure flow requires a comprehensive understanding. Pressure flow can be defined as flow in which the low chord of a bridge becomes inundated and the flow through the bridge opening transitions from free surface flow to a pressurized condition, leading to a submerged or partially submerged bridge deck condition. A pressure flow condition often occurs at a bridge during a flood, potentially leading to bridge failure. Scour of bridge foundations (piers and abutments) represents the largest single cause of bridge failure in the United States (ASCE, 1999). Methodical scour research began in 1949 with the research of E.M. Laursen. Unfortunately, the application of scour research to the design of bridges did not occur until several bridges failed due to local scour. Over the years, bridge scour research has focused on the study of free surface flow. During the past decade, research related to pressure flow scour has become increasingly important. A testing program was developed and performed at the Hydraulics Laboratory of Colorado State University to examine pressure flow effects on scour at and around bridges. Flume experiments were conducted incorporating a physical model of a generic bridge with supporting abutments constructed at an approximate scale of 8:1. In an effort to simulate varying magnitudes of a pressure flow condition, the model was constructed in a manner that permitted the bridge deck to be lowered into the flow. By lowering the bridge deck and holding the level of the approach flow constant, multiple levels of deck submergence could be examined. Six vertical bridge positions, three discharges, two abutment widths and two sediment sizes were incorporated into a matrix comprising 69 tests. Data collected included hydraulic parameters and topographic surveys. Analysis of data collected during the study resulted in the formulation of a set of multivariate linear regression equations enabling the user to estimate abutment, local and deck scour depths during a pressure flow condition. Results of a dimensional analysis indicate that the dominant variables in predicting scour depths for a pressure flow condition include; the critical velocity of a given sediment size, the average velocity under the bridge deck, the height of the bridge deck above the initial and final bed surface, the depth of flow upstream of the bridge and the Froude number of the approach flow. Coefficients of determination for the developed equations ranged from 0.82 to 0.95.
dc.format.mediummasters theses
dc.identifier.urihttp://hdl.handle.net/10217/37826
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relationCatalog record number (MMS ID): 991010566979703361
dc.relationTG320.R624 2000
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.titlePressure flow effects on scour at bridges
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCivil Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
2000_Fall_Robeson_Michael.pdf
Size:
15.26 MB
Format:
Adobe Portable Document Format
Description:
Download

Collections

2000-2019
Theses and Dissertations