Laboratory Study of Pier Location on Scouring Around Bridge Pier in 90-Degree Mild Bend

Bridges are the most useful structures on rivers which floods cause damage to them every year. One of the known factors in bridges destruction is local scouring around the bridge piers. In this study, to investigate the scour depth around the bridge pier in the river bend, experiments were performed in a laboratory flume with a 90-degree bend with  . By placing a cylindrical pier with a diameter of 45 mm at three locations of 30, 45 and 60 degrees along the bend, for three flow Froude numbers, the scouring around the pier under clear water condition was investigated. Natural sand with an average diameter of 0.85 mm is used for the bed materials. The results showed that the maximum scour depth around the bridge pier varies at a different location along the bend. Besides, the flow discharge increase grows the depth and volume of the scour hole at all positions. Additionally, maximum and minimum depth and volume of scouring hole occurs in the second half of the bend at 60- degree position and in the middle of the bend at 45- degree position, respectively. Finally, it was recorded that the development of the sedimentary hill after the pier and its extent in the first half of the bend was higher than the second half of bend. The result also indicated that the maximum and minimum scour depths relative to the pier diameter are equal to 2.24 and 1.22, respectively.