Basin effects on tall bridges in Seattle from M9 Cascadia scenarios. (1st June 2022)

• Record Type: Journal Article
• Authors: Somala, Surendra Nadh; Parla, Rajesh; Mangalathu, Sujith
• Is Part Of: Engineering structures. Volume 260(2022)
• Publication Date: 2022-06-01
• Subjects: Basin amplification -- Tall bridges -- HAZUS -- Scenario earthquakes -- Subduction; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2022.114252
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: Broadband shaking from Cascadia M9 scenario is used to evaluate the basin effect on the seismic vulnerability of bridges. Probabilistic Seismic Damage Models (PSDM) were constructed for bridges situated on basin and bedrock, separately. Identified the impact of basin amplification in Seattle on the collapse fragilities of normal, tall, and super tall bridges. Compared the collapse fragilities with the HAZUS prescribed values. Estimated the influence of relative position of hypocentre on column curvature ductility of bridges. Abstract: 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.