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oai:figshare.com:article/32640984 2026-10-01T16:26:42Z portal_1172 item_type_8 month_year_10_2026

Fluid-structure induced scour in the FlexiArch bridge system Sachie Prabuddha Sathurusinghe Sathurusinghe Arachchillage (24169710) PUREID: 636281143 bridge scour fluid-structure interaction scour progression foundation settlement masonry arch bridge clear-water scour laboratory flume experiments Bridges over waterways are vulnerable to scour, which undermines foundations, reducing stiffness and increasing settlement. This settlement alters the exposure of bridge elements to flow, modifying the flow field and influencing scour progression. However, most hydraulic studies on bridge scour use immobile bridge models, overlooking the effects of settlement due to foundation erosion. This study tests the hypothesis that fluid-structure interaction between bridge settlement and flow significantly affects scour progression. A 1: 10 scale masonry arch bridge model with shallow foundations on an erodible, non-cohesive sediment bed was tested under steady flow in a laboratory flume. Clear-water scour development was compared between immobile and mobile bridge conditions, with the mobile model allowed to settle vertically under its own weight as its foundations were undermined. Results showed that the immobile bridge followed expected scour progression, asymptotically reaching equilibrium. In contrast, scour at the mobile bridge initially followed the same pattern but diverged beyond a critical scour depth, increasing linearly with settlement. This deeper scour—exceeding empirical model predictions for the immobile case—is termed fluid-structure interaction-induced scour, driven by the interaction between settlement and flow. These findings suggest that current scour models, which assume bridge immobility, may underestimate risk when settlement occurs. The linear increase in scour depth with settlement could accelerate scour progression and bridge failure, triggering a scour-settlement cycle. Overall, this study highlights the need for improved scour estimation methods that integrate hydraulic, geotechnical, and structural interactions to enhance bridge safety assessments. Further computational research could help identify conditions where fluid-structure interaction-induced scour becomes significant and where immobile assumptions may underestimate scour damage. Thesis is embargoed until 31 July 2029. 2026-10-01T16:26:42Z Text Thesis 10.17034/32640984.v1 https://figshare.com/articles/thesis/Fluid-structure_induced_scour_in_the_FlexiArch_bridge_system/32640984 All Rights Reserved Open Access after 2029-07-31