Service Limit State Design for Individual Drilled Shafts in Shales
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 143, Issue 12
Abstract
A new service limit state (SLS) design procedure for drilled shafts is described, which utilizes strength resistance factors calibrated to achieve a target probability of failure. The new procedure can be used for varying values of the target probability of failure, and allows the shaft dimensions, soil strength, variability of soil strength, loads, and allowable settlement to be adjusted freely in the design. The procedure eliminates the need to establish resistance factors for the SLS on a case-by-case basis, which is a current practical issue for load and resistance factor design (LRFD). Sensitivity analyses presented indicate that resistance factors for a broad set of SLS design conditions can be reasonably established considering four parameters: the target probability of failure, normalized load, normalized shaft dimension, and the variability of soil/rock strength. Calibrated resistance factors are presented as a function of these four parameters in the form of resistance factor charts, as well as in the form of analytical equations developed through regression of the rigorously calibrated resistance factors. The proposed resistance factors range from 0.1 to 0.4, primarily because of the significant variability and uncertainty associated with side resistance for drilled shafts in shale.
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Acknowledgments
The work presented was funded by the Missouri Department of Transportation (MoDOT), the Center for Transportation Infrastructure and Safety at Missouri University of Science and Technology (MS&T), and the University of Missouri. This support is gratefully acknowledged. The opinions, findings, and recommendations in this publication are not necessarily those of MoDOT or the U.S. Federal Highway Administration. This document does not constitute a standard, specification, or regulation.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 143 • Issue 12 • December 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Apr 20, 2016
Accepted: Jun 7, 2017
Published online: Oct 4, 2017
Published in print: Dec 1, 2017
Discussion open until: Mar 4, 2018
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