Seismic Response of Block-Out Column-Base Plate Connections under Axial Compression and Flexure
Publication: Journal of Structural Engineering
Volume 150, Issue 1
Abstract
Exposed column-base connections are commonly overtopped with concrete to provide an even surface with the surrounding floor slab. To facilitate construction, this concrete is poured, after construction of the floor slab, into a blocked out region of the slab in which the column is placed. The result is a shallowly embedded connection that has significantly higher lateral strength and stiffness with respect to the exposed column-base plate connection without the embedment. This has implications for design and, more importantly, seismic performance assessment. Three large-scale experiments are presented to examine the response of such connections. The connections were subjected to combinations of axial compression and cyclic lateral deformation representative of seismic loading. Significant increases in both strength and stiffness (relative to exposed base plate connections) are noted, arising from the block-out concrete resisting the uplift of the base plate. Stable and ductile hysteretic response (similar to exposed column-base plate connections) is also noted. Failure modes include concrete breakout above the base plate and fracture of the anchors. Results from this study are synthesized with results from previous studies on similar connections to propose a strength model, and to evaluate previously proposed models for stiffness.
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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 authors are grateful to the Charles Pankow Foundation (Award Number 07-18) for providing major funding for this project. The authors thank the American Institute of Steel Construction, and the advisory committee of the project: Mason Walters, Geoff Bomba, and Ali Roufegarinejad of Forell/Elsesser Engineers; Jim Malley of Degenkolb Engineers; Chia-Ming Uang of University of California, San Diego; Subhash Goel of the University of Michigan; Tom Sabol of Engelkirk Structural Engineers; Tim Fraser of Structural Steel Detailing; Tom Kuznick of Herrick Steel; Joe Zona of Simpson Gumpertz and Heger; and Devin Huber of AISC.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 150 • Issue 1 • January 2024
Copyright
© 2023 American Society of Civil Engineers.
History
Received: Dec 22, 2022
Accepted: Aug 14, 2023
Published online: Oct 24, 2023
Published in print: Jan 1, 2024
Discussion open until: Mar 24, 2024
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