Technical Papers
Nov 30, 2020

Reliability Analysis and Design Considerations for Exposed Column Base Plate Connections Subjected to Flexure and Axial Compression

Publication: Journal of Structural Engineering
Volume 147, Issue 2

Abstract

Exposed column base plate (ECBP) connections are commonly used in steel moment resisting frames. Current approaches for their design are well-established from a mechanistic standpoint. However, the reliability of connections designed as per these approaches is not as well understood. A detailed reliability analysis of the prevalent approach in the United States is performed in this study by using 59 design scenarios from steel moment frames subjected to combinations of dead, live, wind, and seismic loads. The analysis is conducted through Monte Carlo sampling reflecting uncertainties in the loads, material properties, component geometry, as well as demand and capacity models for the various components (e.g., base plate, footing, anchor rods) of the connection. Results indicate that the current design approach leads to unacceptable and inconsistent probabilities of failure across the various components. This is attributed to: (1) the use of a resistance factor for the footing bearing stress that artificially alters flexural demands on the base plate, and (2) the calibration of resistance factors for the plate and anchors without appropriate consideration of variability in demands. Two alternative approaches are examined as prospective refinements to the current approach. One eliminates the resistance factor for the bearing stress when used to determine flexural demands in the base plate, while the other considers overall failure of the connection rather than failure of individual components within the connection. For both approaches, new resistance factors are calibrated to provide consistent and acceptable probabilities of failure across all limit states and all types of loading. Design and cost implications of these alternative approaches are summarized.

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Data Availability Statement

Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.

Acknowledgments

The first author would like to acknowledge the financial support from China Scholarship Council (CSC, under Grant No. 201608330227) and University College London (UCL) through a joint research scholarship for his PhD study. Support from the Pacific Earthquake Engineering Research Center is also gratefully acknowledged by the corresponding author.

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Go to Journal of Structural Engineering
Journal of Structural Engineering
Volume 147Issue 2February 2021

History

Received: Mar 9, 2020
Accepted: Sep 2, 2020
Published online: Nov 30, 2020
Published in print: Feb 1, 2021
Discussion open until: Apr 30, 2021

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Authors

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Biao Song, S.M.ASCE
Ph.D. Candidate, Dept. of Civil, Environmental and Geomatic Engineering, Univ. College London, London WC1E 6BT, UK.
Carmine Galasso, A.M.ASCE https://orcid.org/0000-0001-5445-4911
Associate Professor, Dept. of Civil, Environmental and Geomatic Engineering, Univ. College London, London WC1E 6BT, UK; Associate Professor, Classe di Scienze, Tecnologie e Società, Scuola Universitaria Superiore Pavia, Pavia 27100, Italy. ORCID: https://orcid.org/0000-0001-5445-4911
Amit Kanvinde, M.ASCE [email protected]
Professor, Dept. of Civil and Environmental Engineering, Univ. of California, Davis, CA 95616 (corresponding author). Email: [email protected]

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