Methodology to Account for the Impact of Stress History in Layered Soils for Seismic Vulnerability Assessment of Scoured Bridges
Zhang, Y., and Tien, I., “Methodology to Account for the Impact of Stress History in Layered Soils for Seismic Vulnerability Assessment of Scoured Bridges,” Structure and Infrastructure Engineering, Vol. 18, No. 5, pp. 653-677, December 2020
Abstract — Scour has been recognized as one of the leading causes of bridge collapse in the United States. Therefore, it is essential to be able to build models that accurately capture the response of bridges vulnerable to scour, including those located in layered rather than homogeneous soil deposits. Simple removal of soil springs due to scour ignores the effect of stress history for layered soils, which can lead to unconservative designs of foundations. This article proposes a methodology called the equivalent stress history and layered effects (ESHaLE) approach to capture the impact of soil stress history of layered soils on vulnerability assessment of scoured bridges. It utilises conservation of strength and mass to derive corresponding soil and depth parameters. Results show that neglecting to include stress history impacts in layered soils can lead to an underestimation of the single pile axial displacements by up to 35% in static analysis, and underestimation of the probability of exceeding bridge deck deflection thresholds by up to 25% in seismic fragility assessment. The study presents a method to include both soil stress history and layered effects in soil modeling and shows the importance of including these soil effects in the assessment of bridges vulnerable to scour.
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