Effects of collars on local scour around semi-circularend bridge abutments

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2011
Daşkın, Süeyla
During severe floods, bed material around bridge piers and abutments are scoured by the flow and as a result, bridges are subject to damages. These damages are mostly unrepairable and can result in loss of lives and property. In this thesis study, abutment scour under clear-water condition was investigated and collars were tested as scour countermeasures around the abutments. The experimental study was carried out in a rectangular channel with an almost uniform cohesionless bed material of d50=1.50 mm for a test period of 3-hours. The channel was 28.5 m long and 1.5 m wide. The erodible bed material was placed into the test section that was 5.8 m long and 0.48 m deep. For this thesis study, 60 experiments were carried out with and without various collars placed at different elevations around the abutments. The scour formation around the abutments with collars was observed and scour reduction efficiencies of the collars were studied. Experiment results were compared with the previous studies of Doğan (2008) and Kayatürk (2005) in terms of sediment size, abutment shape and flow depth, and the effects of these factors on collar's scour reduction efficiency were studied. Based on the results of the experimental studies, it was observed that scour depths decreased as the collar width increased and the collar placed deeper into the sediment bed for a given abutment length. When the present study and the previous studies were compared, it was observed that sediment size and flow depth had no significant effect on the scour reduction performances of the collars.

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Citation Formats
S. Daşkın, “Effects of collars on local scour around semi-circularend bridge abutments,” M.S. - Master of Science, Middle East Technical University, 2011.