INVESTIGATION OF FLOOD FORCES ON MASONRY ARCH BRIDGES USING SPH

Masonry arch bridges constitute a substantial proportion of the existing bridge stock in the UK and elsewhere. Although this durable bridge form often demonstrates good structural performance under normal service loading, bridges spanning watercourses are vulnerable to damage from flood-induced loads. Fluvial flooding generates both hydrostatic and hydrodynamic effects on the arch superstructure in addition to well known-scour effects on the substructure, all of these have the potential to cause structural failure. While research on scour is relatively well advanced, quantification of the hydrodynamics forces on the bridge superstructure is not yet comprehensively understood. Where fast flood flows come into contact with the bridge superstructure, highly transient behaviour is observed, this may develop into violent interactions, particularly where floating debris is involved. This paper explores the novel use of smoothed particle hydrodynamics (SPH) to capture detailed pressure time histories and associated spatial distribution on masonry arches subject to fluvial flooding. SPH uses moving particles to represent the flow and is therefore ideal to simulate highly transient and potentially violent free-surface flows encountered during fast events. A typical arch bridge and representative flood flows are simulated in order to demonstrate the capability of the method. Under typical real-life flood flows, significant hydrodynamic pressures are generated which need to be considered in the assessment of such structures.