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Every year many bridges around the world fail most of them due to scouring at their piers and abutments. Collapse of bridges cause heavy damage, and therefore, study on the control of scouring at the bridge site plays an important rule in bridge design.
In this study application of half collar on rectangular piers is proposed as a simple method to control scouring. Experiments show that installation of a small half collar with a width. equal to half of the pier
, width, at 10% of flow depth under the streambed level- Gould reduce depth of scour hole by 40%. Experiments also show
. that a larger' collar with a width equal to the pier width when installed at streambed level reduces the scour hole by 80%. Double collar was also tested. It was found that a small collar at 10% of depth above another small collar at the bed level
increases its efficiency by more than 16%.