Effect of Spacing and Skewness on Side-by-Side Bridge Piers

The impact of pier shapes, spacing, skew angle, and non-uniform sediment on local scour brought on by clear-water flow around three side-by-side (rectangular and lenticular) bridge piers was investigated experimentally.The experiments varied the spacing between piers' and four different pier skew angles (0, 30, 45, and 60), the sediment has mean particle size (d50=0.873mm), and a flow depth of 5 cm, and S/Dp=1 and 3.The results show that under all flow conditions, Maximum Scour Depth (MSD) were found in front of the bridge piers, regardless of the size of the piers.Because of the extensive exposed area, the rectangular form has the largest MSD=10.6,8.8, and 6.5 for P1, P2, and P3, respectively at a skew angle of 30 and S/Dp=1, otherwise, the lenticular shapes are the best for piers Since they reduce scour depth by 30% compared to rectangular shapes when the skew angle increased from (0-30) the scour depth increased, but when the skew-angle was more than 30 the scour depth decreased for the same S/Dp.When 45, the scour downstream increases.The scour depth decreases when the spacing increases (=0 and 30).On the other hand, for the skew angle of 45, the scour depth is greater when (S/Dp=1) compared to (S/Dp=3) when the skew angle is (0 -30), but when the skew angle is more than 30, the scour depth increased as the spacing between the piers increased.Additionally, it shows the MSD decreased as the armor layer's grain size increased.