Soils and Foundations

Soils and Foundations

Volume 60, Issue 5, October 2020, Pages 1112-1130
Soils and Foundations

Technical Paper
Fragility analysis of drilled shafts in sand – an analytical correspondence between reliability index and factor of safety

https://doi.org/10.1016/j.sandf.2020.05.005Get rights and content
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Abstract

This paper establishes an analytical correlation between factor of safety (FS) and reliability index β values commonly used in the design of drilled shafts in sand. This is achieved through fragility analysis of unit shaft and base resistances, calculated using finite element analysis-based capacity calculation equations, for drilled shafts. Analytical fragility curves are developed for allowable unit resistances along the pile shaft and at the pile base. Developed fragility curves are used to map FS values with corresponding values of β. Such analytical FS–β correspondence is not well established in literature. Comparison of results from fragility analysis with those obtained through conventional Monte Carlo simulations reveals excellent agreement. Developed FS-β correlation is employed in reliability analysis to estimate load and resistance factors corresponding to different FS values. Evaluated load and resistance factors compare very well with AASHTO specifications.

Keywords

Drilled shafts
Factor of safety
Reliability index
Fragility
Load and resistance factors

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Peer review under responsibility of The Japanese Geotechnical Society.