Statistical, Risk, and Reliability Analyses of Bridge Scour

Briaud, J-L; Gardoni, Paolo; Yao, Congpu

doi:10.1061/(asce)gt.1943-5606.0000989

Cited by 63 publications

(17 citation statements)

References 7 publications

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“…In two recent papers, a general approach to probabilistic scour hazard modeling was reported, which starts with the deterministic scour estimation equation then incorporates model bias and random errors [5]. Furthermore, Briaud et al [6] concluded that for shallow foundations supporting bridge structures, the design scour depth needs to be 2.0-2.5 times of the HEC-18 estimates to ensure that the probability of exceeding the estimated scour depth be less than 0.001, even that both HEC-18 (Sand and Clay) methods are considerably conservative compared with measured bridge scour data. Besides probabilistic scour assessment for bridge foundations, however, these two efforts did not address the multi-hazard effects on a bridge as a system if earthquakes are involved.…”

Section: Probabilistic Methodology 21 Related Workmentioning

confidence: 99%

Multi-Hazard Assessment of Seismic and Scour Effects on Rural Bridges with Unknown Foundations

Guo¹,

Dai²,

Chen³

2019

Earthquakes - Impact, Community Vulnerability and Resilience

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This chapter proposes a probabilistic framework for assessing seismic and scour effects on existing river-crossing bridge structures. The emphasis is on bridge structures in rural areas, for which it has been recognized that a large number of rural bridges have unknown foundation types and further are subject to both flooding-induced scour and seismic damage. With a review of the US-based rural bridges, this chapter presents a probabilistic framework for bridge performance assessment. Using a representative rural bridge model, the fragility results for the bridge reveal that scour tends to be beneficial in reducing structural damage at slight to moderate seismic intensities and to be detrimental in increasing collapse potential at high-level intensities. The demand hazard curves further quantify probabilistically the occurrence of local damage and global collapse, and systematically reveal the complex effects of scour as a hydraulic hazard on bridge structures.

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Section: Probabilistic Methodology 21 Related Workmentioning

confidence: 99%

Multi-Hazard Assessment of Seismic and Scour Effects on Rural Bridges with Unknown Foundations

Guo¹,

Dai²,

Chen³

2019

Earthquakes - Impact, Community Vulnerability and Resilience

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“…Bridge overload and lateral impact forces from trucks, barges/ships, and trains constitute 20% of the total bridge failures. Other frequent principal causes are design, detailing, construction, material, and maintenance.” This study confirms results of the previous analysis in Rhodes and Trent, who indicated “average annual flood‐damage repair costs of approximately $50 million for highways on the Federal‐aid system.” In addition to scour, authors underline the role of morphological evolution of the rivers, so that bridges “experience problems with aggradation, degradation, bank erosion, and lateral channel shift during their useful life.” The relevance of scour on bridge failure in the United States has been recently analyzed in detail by Briaud et al…”

Section: Introductionmentioning

confidence: 99%

“…Evolution of codes is expected to grant higher level of safety for bridges (some evidence comes from a time series analysis in Briaud et al). However, it also makes several existing structures to be no more compliant with the new standards, considering the increase of the nominal traffic and wind loads in the last 60 years and the modification of reference hydraulic hazard scenarios due to climate change .…”

Section: Introductionmentioning

confidence: 99%

Actions monitoring as an alternative to structural rehabilitation: Case study of a river bridge

Ballio

Franzetti

Crotti

et al. 2018

Struct Control Health Monit

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Summary A number of river bridges collapse worldwide every year during flood events, due to combination of actions including traffic loads, water and wind load, riverbed degradation, and accumulation of debris. Incidence of failure is higher for relatively old bridges that may have been designed without adequate consideration for some of such actions, in particular the scour potential at piers and abutments; in this case, consolidation of bridge foundations may be required. As an alternative to structural rehabilitation, we propose here real‐time management as a nonstructural risk‐mitigation measure: Data from a monitoring system aid the bridge managers to decide whether a bridge should be partially or totally closed to traffic in the case that forecasted environmental conditions indicate that the structure may exit its safe operational domain. A peculiar feature of the present proposal is that the monitoring system focuses on the evaluation of the environmental actions on the structure rather than on the health state of the structure itself: Such choice allows sufficient lead time for bridge closure. Bridge management may not prevent the damage of the structure but should avoid casualties. The methodology is presented with reference to the field case of a bridge over the river Po (Italy); its generalization to a larger variety of conditions is also discussed.

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“…If a bridge must be closed for repairs or fails altogether, there are cascading secondary costs due to lost time and decreased productivity of travelers, not to mention the very real risk of injuries and fatalities if scour damage results in unexpected and sudden bridge failure. When these secondary costs are considered, the total average cost of a single bridge failure is estimated at $13 million (Briaud et al 2014)-and over 23,000 bridges were classified as critical in 2011 in the United States, representing nearly 5 % of all bridges (Arneson et al 2012). Given that scour is the leading cause of bridge failure and that hundreds of bridges are expected to experience flooding in excess of the 100-year flood annually (Arneson et al 2012), the scale of this infrastructure management problem is clear.…”

Section: Bridge Scour and Floodplain Accessmentioning

confidence: 99%

Heuristic assessment of bridge scour sensitivity using differential evolution: case study for linking floodplain encroachment and bridge scour

et al. 2016

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Background: Stakeholders are often required to make judgments and decisions about the tradeoffs between multiple competing objectives inherent in any engineering design. Design optimization can provide decision support for such situations, but often prescribes that only a single design solution be selected for a given set of preferences. The purpose of this study is to frame an objective function for assessing how the sensitivity of one objective relative to another varies in space and to demonstrate the method using a real site, with spatially-dependent floodplain access and bridge scour as the objective tradeoffs. Bridge scour is a widespread and expensive infrastructure problem, and the proposed methodology provides the ability to assess how the sensitivity of bridge scour to floodplain access varies at different locations in a river reach. Results:The site chosen for demonstration purposes was the Lewis Creek in the vicinity of the Quinlan Covered Bridge in Charlotte, VT. Differential evolution (DE) was wrapped around an existing HEC-RAS model. The decision variables corresponded to floodplain access at locations up and downstream of the bridge; the objective function was constructed so that optimal solutions may be interpreted as relative salience of floodplain access to bridge scour. Multiple weightings of the objectives were used to verify that the rank-order of locations was robust. The optimal DE solutions for all weightings resulted in the same sensitivity ranking of locations, providing evidence that the analysis is not dependent on a particular choice of stakeholder objective weightings. Conclusions:For systems with spatially dependent variables that impact a constraint or objective of interest to stakeholders, a tool for identifying locations where that variable has a particularly strong or weak impact (e.g. where floodplain access is more or less important for bridge scour) has obvious advantages. This study demonstrates a method for conducting such a sensitivity analysis using a numerical optimization scheme. On the real test site, the sensitivity ranking was consistent across multiple stakeholder weightings, providing evidence that the technique is robust, and one that can be used at multiple stages of design. This work demonstrates the utility of a novel interpretation of optimization results in which locations are ranked according to the relative sensitivity of competing objectives.

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Statistical, Risk, and Reliability Analyses of Bridge Scour

Cited by 63 publications

References 7 publications

Multi-Hazard Assessment of Seismic and Scour Effects on Rural Bridges with Unknown Foundations

Multi-Hazard Assessment of Seismic and Scour Effects on Rural Bridges with Unknown Foundations

Actions monitoring as an alternative to structural rehabilitation: Case study of a river bridge

Heuristic assessment of bridge scour sensitivity using differential evolution: case study for linking floodplain encroachment and bridge scour

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