SCOUR-INDUCED FAILURE OF MASONRY ARCH BRIDGES: CAUSES AND COUNTERMEASURES

B Solan, ALIREZA NOWROOZPOUR, Paul Clopper, Claire Watters, Robert Ettema

Research output: Chapter in Book/Report/Conference proceedingConference contribution

109 Downloads (Pure)

Abstract

This paper discusses how flow conditions and consequent scour of channel bed induces the failure of short-span, masonry arch bridges over small to medium sized rivers. Such bridges are common in Ireland, the U.K. and Europe. A factor frequently complicating failure is that such bridges typically are deemed historic structures and, therefore, are expensive to repair. A significant hydraulic-engineering factor is that, these bridges readily choke approaching flows, especially under large return period flooding conditions. The bridge flow area quickly decreases once flow stage reaches the crown of the arch barrel. Flume experiments, undertaken with choked flow condition, showed that three locations of masonry arch bridges are particularly prone to scour-induced erosion: piers (multi-span only), abutment corners and the channel bed immediately downstream of the bridge (in the case of a paved or protected bridge inverts). Scour can be reduced only modestly by streamlining abutments by means of wing walls, and cutwaters on piers, because of flow choking. The use of stone pitching to armour the riverbed around abutments and piers prevents scour at the front of, and beneath, the bridge. However, supercritical flow through the bridge opening may scour the channel bed immediately downstream of a bridge. Alternative scour-mitigation measures are suggested. The increased failure incidence of these bridges has raised concerns in the U.K. and Ireland that many masonry arch structures will be imperilled by the effects of greater flow rates associated with climate change and watershed urbanization. The situation is complicated by the age of the structures and the lack of accurate bridge records.
Original languageEnglish
Title of host publicationE-proceedings of the 38th IAHR World Congress
Publication statusPublished - 6 Sep 2019

Keywords

  • alluvial river; arch bridges, flow contraction, asset failure

Fingerprint Dive into the research topics of 'SCOUR-INDUCED FAILURE OF MASONRY ARCH BRIDGES: CAUSES AND COUNTERMEASURES'. Together they form a unique fingerprint.

  • Cite this

    Solan, B., NOWROOZPOUR, ALIREZA., Clopper, P., Watters, C., & Ettema, R. (2019). SCOUR-INDUCED FAILURE OF MASONRY ARCH BRIDGES: CAUSES AND COUNTERMEASURES. In E-proceedings of the 38th IAHR World Congress