Scour and the Stability of Short-Span, Masonry Arch Bridge: findings from a diagnostic, flume study

B Solan, Rob Ettema, Claire Watters, Gerard Hamill, Donal Ryan

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

Abstract

This paper presents findings from diagnostic, flume experiments conducted to investigate how local scour development de-stabilizes short-span masonry arch bridges. A review conducted by the writers indicates that a significant proportion of the existing bridge stock in Ireland, the UK, Europe and North-Eastern USA are this bridge type. To complicate matters, these bridges often are deemed historic structures, and thus are difficult to simply replace. In recent years, spreading urbanization and increased frequency of extreme rainfall events in the U.K. and Ireland have increased the failure incidence of these old bridges. In addition to their inadequate flow opening, these bridges are usually founded on shallow footings of uncertain condition. The footings of some bridges supported on timber piles have weakened with age. The flume experiments involved flow and scour with the upstream face of arch openings fully submerged, creating an orifice-flow condition through the arch opening. The experiments showed that two locations of masonry arch bridges are particularly prone to settlement cracking owing to clearwater scour-induced undermining. These locations are at (i) the footings at the upstream corners of arch-bridge abutments, and (ii) footings beneath piers between arches (in multi-span bridges). The findings further show that greatest scour depth normally developed at the center-pier linking adjoining arches, however the addition of cutwaters shifted the location of the maximum scour so as to be more central in the arch opening. Additionally, the findings show that scour depth and consequent undermining can be reduced somewhat by streamlining abutments by means of wing walls, and piers by means of cutwaters. Where these remedial works are impracticable, the use of stone pitching to armour the riverbed around abutments and piers is a very effective way to prevent scour. Yet, once the scour is mitigated at the entrance of a short-span arch, flow contraction and acceleration through the opening may scour the channel bed immediately downstream of an arch. Subsequent erosion and head-cutting of the downstream bed can then migrate upstream to adversely affect the stability of the bridge. Ireland and the UK face substantial issues in determining how to ensure the long-term stability of historic, short-span, masonry arch bridges
LanguageEnglish
Title of host publicationCERAI 2018
Pages56-61
Number of pages6
Publication statusPublished - 29 Aug 2018

Fingerprint

Masonry bridges
Arch bridges
Scour
Arches
Piers
Abutments (bridge)
Bridge piers
Armor
Experiments
Timber
Orifices
Piles
Rain
Erosion

Keywords

  • Masonry arch bridges
  • Foundation scour
  • Extreme weather events
  • Asset management
  • Resilience

Cite this

Solan, B., Ettema, R., Watters, C., Hamill, G., & Ryan, D. (2018). Scour and the Stability of Short-Span, Masonry Arch Bridge: findings from a diagnostic, flume study. In CERAI 2018 (pp. 56-61)
Solan, B ; Ettema, Rob ; Watters, Claire ; Hamill, Gerard ; Ryan, Donal. / Scour and the Stability of Short-Span, Masonry Arch Bridge: findings from a diagnostic, flume study. CERAI 2018. 2018. pp. 56-61
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Solan, B, Ettema, R, Watters, C, Hamill, G & Ryan, D 2018, Scour and the Stability of Short-Span, Masonry Arch Bridge: findings from a diagnostic, flume study. in CERAI 2018. pp. 56-61.

Scour and the Stability of Short-Span, Masonry Arch Bridge: findings from a diagnostic, flume study. / Solan, B; Ettema, Rob; Watters, Claire; Hamill, Gerard; Ryan, Donal.

CERAI 2018. 2018. p. 56-61.

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

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AU - Solan, B

AU - Ettema, Rob

AU - Watters, Claire

AU - Hamill, Gerard

AU - Ryan, Donal

PY - 2018/8/29

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N2 - This paper presents findings from diagnostic, flume experiments conducted to investigate how local scour development de-stabilizes short-span masonry arch bridges. A review conducted by the writers indicates that a significant proportion of the existing bridge stock in Ireland, the UK, Europe and North-Eastern USA are this bridge type. To complicate matters, these bridges often are deemed historic structures, and thus are difficult to simply replace. In recent years, spreading urbanization and increased frequency of extreme rainfall events in the U.K. and Ireland have increased the failure incidence of these old bridges. In addition to their inadequate flow opening, these bridges are usually founded on shallow footings of uncertain condition. The footings of some bridges supported on timber piles have weakened with age. The flume experiments involved flow and scour with the upstream face of arch openings fully submerged, creating an orifice-flow condition through the arch opening. The experiments showed that two locations of masonry arch bridges are particularly prone to settlement cracking owing to clearwater scour-induced undermining. These locations are at (i) the footings at the upstream corners of arch-bridge abutments, and (ii) footings beneath piers between arches (in multi-span bridges). The findings further show that greatest scour depth normally developed at the center-pier linking adjoining arches, however the addition of cutwaters shifted the location of the maximum scour so as to be more central in the arch opening. Additionally, the findings show that scour depth and consequent undermining can be reduced somewhat by streamlining abutments by means of wing walls, and piers by means of cutwaters. Where these remedial works are impracticable, the use of stone pitching to armour the riverbed around abutments and piers is a very effective way to prevent scour. Yet, once the scour is mitigated at the entrance of a short-span arch, flow contraction and acceleration through the opening may scour the channel bed immediately downstream of an arch. Subsequent erosion and head-cutting of the downstream bed can then migrate upstream to adversely affect the stability of the bridge. Ireland and the UK face substantial issues in determining how to ensure the long-term stability of historic, short-span, masonry arch bridges

AB - This paper presents findings from diagnostic, flume experiments conducted to investigate how local scour development de-stabilizes short-span masonry arch bridges. A review conducted by the writers indicates that a significant proportion of the existing bridge stock in Ireland, the UK, Europe and North-Eastern USA are this bridge type. To complicate matters, these bridges often are deemed historic structures, and thus are difficult to simply replace. In recent years, spreading urbanization and increased frequency of extreme rainfall events in the U.K. and Ireland have increased the failure incidence of these old bridges. In addition to their inadequate flow opening, these bridges are usually founded on shallow footings of uncertain condition. The footings of some bridges supported on timber piles have weakened with age. The flume experiments involved flow and scour with the upstream face of arch openings fully submerged, creating an orifice-flow condition through the arch opening. The experiments showed that two locations of masonry arch bridges are particularly prone to settlement cracking owing to clearwater scour-induced undermining. These locations are at (i) the footings at the upstream corners of arch-bridge abutments, and (ii) footings beneath piers between arches (in multi-span bridges). The findings further show that greatest scour depth normally developed at the center-pier linking adjoining arches, however the addition of cutwaters shifted the location of the maximum scour so as to be more central in the arch opening. Additionally, the findings show that scour depth and consequent undermining can be reduced somewhat by streamlining abutments by means of wing walls, and piers by means of cutwaters. Where these remedial works are impracticable, the use of stone pitching to armour the riverbed around abutments and piers is a very effective way to prevent scour. Yet, once the scour is mitigated at the entrance of a short-span arch, flow contraction and acceleration through the opening may scour the channel bed immediately downstream of an arch. Subsequent erosion and head-cutting of the downstream bed can then migrate upstream to adversely affect the stability of the bridge. Ireland and the UK face substantial issues in determining how to ensure the long-term stability of historic, short-span, masonry arch bridges

KW - Masonry arch bridges

KW - Foundation scour

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KW - Asset management

KW - Resilience

M3 - Conference contribution

SN - 978-0-9573957-3-2

SP - 56

EP - 61

BT - CERAI 2018

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Solan B, Ettema R, Watters C, Hamill G, Ryan D. Scour and the Stability of Short-Span, Masonry Arch Bridge: findings from a diagnostic, flume study. In CERAI 2018. 2018. p. 56-61