Stream Power Application for Bridge-Damage Probability Mapping Based on Empirical Evidence from Tropical Storm Irene

On August 28, 2011, Tropical Storm Irene hit the state of Vermont with a severity that deposited 100–200 mm (4–8 in.) of rain across the state and resulted in damage or failure of over 300 bridges. The analysis of available data sets helped identify a set of 313 bridges (with a span greater than 6 m) damaged in a single state from a single extreme flood event that caused a 12-h rainfall recurrence interval that exceeded 500 years in some areas and 100 years throughout most of the affected areas. Based on available damage reports and photographs, the observed bridge damage was grouped into four levels of severity. This paper links watershed stream power to the observed bridge damage, develops a process for quantifying the hazard at bridges both as a case study and for future storms, and uses stream power as a hazard metric to produce probabilistic predictions of bridge vulnerability. The analysis also offers a comparison between damaged bridges and bridges that were not damaged in Tropical Storm Irene. Specific stream power (SSP) and the event-based Irene-specific stream power (ISSP) were computed and found to be both statistically significant at discriminating between damaged and nondamaged bridges, as well as between damage levels. The application of the empirical fragility curve analysis for SSP and ISSP produces a probability of damage generated from the results collected from Tropical Storm Irene. Spatially mapping the bridge-damage probability from an extreme event like Tropical Storm Irene enables the hazard to be effectively displayed over a broad range of scales (e.g., stream reaches, select watershed, statewide). The methodology presented here can be applied to other geographic settings and storm events of interest, and to the best of the authors’ knowledge, this is the first investigation comparing site-specific stream power to observed bridge damage at a network level.


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  • Accession Number: 01644167
  • Record Type: Publication
  • Files: TRIS, ASCE
  • Created Date: Aug 29 2017 9:54AM