Basin effects on tall bridges in Seattle from M9 Cascadia scenarios

Seattle is located on deep (a few kilometers) basins that have the potential to amplify long periods of shaking in the event of an earthquake. Even the latest design provisions in the United States do not yet factor basin effects into the design. Cascadia has not experienced any earthquake close to M9 since 1700 and so the United States Geological Survey has put together several scenario earthquakes for the impending M9 event waiting to happen in the Cascadia subduction zone. This study focuses on bridges, specifically tall bridges, and evaluates the influence of basin amplification on bridge response and collapse fragilities. Bridge fragility is estimated using a cloud approach, accounting for different scenarios of varying source parameters (asperities, stress drops, subevents, etc.). The results from the current study reveal interesting aspects of basin amplification on the bridge vulnerability. A comparison with HAZUS fragility shows that tall bridge collapse fragility is underestimated, especially when the site is located on deep basins.

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  • English

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  • Accession Number: 01845371
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 17 2022 10:47AM