Checking the Accuracy of Selected Formulae for both Clear Water and Live Bed Bridge Scour
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Abstract
Due to severe scouring, many bridges failed worldwide. Therefore, the safety of the existing bridge (after contrition) mainly depends on the continuous monitoring of local scour at the substructure. However, the bridge's safety before construction mainly depends on the consideration of local scour estimation at the bridge substructure. Estimating the local scour at the bridge piers is usually done using the available formulae. Almost all the formulae used in estimating local scour at the bridge piers were derived from laboratory data. It is essential to test the performance of proposed local scour formulae using field data. In this study, the performance of selected bridge scours estimation formulae was validated and statistically tested using field data for existing bridges in Canada, Iraq (Kufa, Najaf), Pakistan, Bangladesh, and India. The validated formulae were HEC-18, Forehlich, and Johnson. The validation was conducted by comparing the predicted local scour depths obtained from applying the above selected formulae with the local scour depths obtained from the field data. The comparison between them was presented using a scattergram. However, statistical tests were used to present the accuracy of the local scour predictions. The tests were conducted using three statistical indices, namely, Theil’s coefficient (U), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). Among the tested formulae, the Jonson formula gave satisfactory performance since the values of U, MAE, and RMSE were found to be 0.112, 1.351, and 1.650, respectively.
Article received: 17/7/2022
Article accepted: 1/9/2022
Article published: 1/2/2023
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References
Al-Hassani, N. Z., and Mohammad, T. A., 2021. Impact of the Weir Slit Location, the Flow Intensity and the Bed Sand on the Scouring Area and Depth at the Dam Upstream, Journal of Engineering, 27(5), pp. 49–62. DOI: 10.31026/j.eng.2021.05.04.
Arneson, L. A., Zevenbergen, L. W., Lagasse, P. F., and Clopper, P. E., 2012. Evaluating scour at bridges (No. FHWA-HIF-12-003), National Highway Institute (US).
Froehlich, D. C., 1988. Analysis of onsite measurements of scour at piers, In Hydraulic Engineering: Proceedings of the 1988 National Conference on Hydraulic Engineering , pp. 534-539.
Johnson, P. A., 1995. Comparison of pier-scour equations using field data, Journal of Hydraulic Engineering, 121(8), pp. 626-629.
Melville, B. W., and Coleman, S. E., 2000. Bridge scour, Water Resources Publication.
Mohamed, T. A., Pillai, S., Noor, M. J. M. M., Ghazali, A. H., Huat, B. K., and Yusuf, B., 2006. Validation of some bridge pier scour formulae and models using field data, Journal of King Saud University-Engineering Sciences, 19(1), pp., 31-40.
Pruebas, 2020. Scour and its relation to the collapse of bridges. Technical Report, IDVA Engineering Company, Spain, Available at: < https://www.idvia.es/en/scour-and-its-relation-to-the-collapse-of-bridges-2>
Qadar A., 1981. The Vortex Scour Mechanism at Bridge Piers, Proceedings of the Institution of Civil Engineers, 71(3), pp. 739-757.
Subramanya, K., 2009. Flow in open channels. McGraw-Hill Publishing Company, New Delhi, India.
Van Rijn, L. C., 1993. Principles of sediment transport in rivers, estuaries and coastal seas (Vol. 1006, pp. 11-3), Amsterdam: Aqua publications.
Wattan, S. A. A., and Al-Bakri, M., 2019. Development of Bridges Maintenance Management System based on Geographic Information System Techniques (Case study: AlMuthanna Iraq), Journal of Engineering, 25(7), pp. 21–36, DOI: 10.31026/j.eng.2019.07.02.