Local Scour around Different-Shaped Bridge Piers

Local scour around piers is the major cause of bridge failures, and its estimation is critical for safe design. The present study aims to identify a modified pier shape that can reduce local scour compared to a circular pier. In addition, M۵ models are developed for maximum scour depth prediction and compared with the existing equations available in the literature. Thus, the effect of pier shape and alignment on local scour is experimentally investigated using three pier models with the same cross-sectional area placed in isolated and tandem arrangements under clear-water conditions. These are circular (M۱) and two modified pier shapes (M۲ and M۳), where M۲ is a combination of semi-circle and triangle oriented either way (M۲a and M۲b), and M۳ is a further modification to M۲a with a small protrusion on the semi-circular end. The results showed that the local scour depth for aligned (skew angle, α = ۰°) M۲a, M۲b, and M۳ piers is reduced by ۲۳.۵%, ۵۰%, and ۵۵%, respectively, compared to the M۱ pier but not if α > ۰°. In tandem arrangements, the least scour depths observed around M۱ and M۲a at X = ۱.۰D (X is clear-spacing between piers and D is pier diameter), and M۳ and M۱ at X = ۱.۷۵D placed as front and rear pier, respectively. It is observed that the developed M۵ models are more accurate compared to the existing equations. Flow intensity (V/Vc) and αhave more influence on the scour depth prediction around tandem and isolated piers, respectively. Doi: ۱۰.۲۸۹۹۱/CEJ-۲۰۲۴-۰۱۰-۰۶-۰۱۹ Full Text: PDF

Keywords:

Scour Control , Pier Shape , Skewed Piers , Tandem Piers , Scour Depth Prediction , M۵ Model.