Local scour at complex bridge piers–experimental validation of current prediction methods

Prediction of maximum scour depth at complex bridge piers is frequently decisive for the safe design of bridges. Some methods are available for this purpose but, due to the discrepancies of their predictions, such methods deserve further validation on the basis of new and independent data sets. For this purpose, clear-water experiments were performed by systematically varying the pile-cap elevation of a particular pier shape. Equilibrium scour depths were reached and measured and the comparison of predictions with measurements was established. The method of Sheppard and Renna, published in 2005, was found to predict with the highest accuracy the attained results for the tested complex pier. However, it should be stressed that this method slightly underestimates scour when the pile cap is out of the water or partly imbibed in the flow. It also under-predicts the scour depth when the pile cap is deeply buried in the bed. © 2019 Indian Society for Hydraulics.