Identify most promising temporal scour depth formula for circular piers proposed over last six decades

Abstract

Temporal scour depth (dst) measurement at bridge piers is a significant issue for application engineers because accurate prediction is required for real-time monitoring. Although several formulas were employed, definitive study is still needed to determine which formula predicts most accurately. Therefore, here, a comparative analysis of dst prediction formulas, at circular piers in clearwater conditions, is performed using laboratory datasets for evolution over 57-years based on seven parameters: sediment coarseness, flow shallowness, constriction ratio, threshold-Froude number, sediment uniformity, relative density, time. Goal is also to select best option that will provide more useful compromise solution concept rather than examining ideal solutions based on inconsistencies. Therefore, useful statistical influence factors are used to perform 11 literature formulas with a newly derived formula in relation to their fitting coefficients. Weightage of each influencing factor is calculated using equal weightage and CRITIC methods. Ranking of each formula is determined using compromise programming. Overall study reveals that NCHRP (2011) formula is still most useful to determine dst if equilibrium scour depth (dse) and equilibrium time (te) are known. Melville and Chiew's (1999) formula is very close to NCHRP (2011). But without presuming dse and te, the newly proposed formula most accurately predicts the dst.