Column Base Connections for Hollow Steel Sections: Seismic Performance and Strength Models
Publication: Journal of Structural Engineering
Volume 141, Issue 7
Abstract
The seismic response of exposed hollow steel section columns to base plate connections is examined through a series of eight experiments. The prototype-scale tests investigate a range of variables including base plate size and thickness, column size, and anchor rod layout (four rods in two rows, and eight rods in three rows). The specimens were subjected to cyclic flexural loading and instrumented to provide direct (rather than inferred) measurement of tension forces in the anchor rods. All the specimens showed excellent deformation capacity, with a stable hysteretic response for base rotations as large as 0.057–0.13 rad. Three specimens failed by fracture of the weld between the column and the plate, whereas five did not fracture. Evaluation of the test data against the current design approach prevalent in the United States suggests that (1) the design approach is reasonably conservative but (2) does not address the effect of the third (i.e., central) row of anchor rods; as a result, it cannot be used to design them. A new design method is presented that explicitly incorporates the third row of rods. The new approach is evaluated against the test data and it is determined that the new approach reflects the internal mechanics of the connections in an improved way while providing more accurate estimates of forces in the rods. Recommendations for the design of the connections are outlined, along with ongoing work that leverages the deformation capacity of these connections for displacement-based design. The limitations of the study are summarized, especially in terms of challenges to the generalization of its findings.
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Acknowledgments
The authors gratefully acknowledge Wildeck for donating the column specimens and providing funding. The assistance of Bill Sluis, Daret Kehlet, Jeffrey Louie, Eliot Wu, and Kimberly Stillmaker during the testing is also greatly appreciated. The opinions in this article are those of the authors and do not represent those of the sponsors.
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Information
Published In
Journal of Structural Engineering
Volume 141 • Issue 7 • July 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Feb 15, 2014
Accepted: Jun 10, 2014
Published online: Aug 12, 2014
Discussion open until: Jan 12, 2015
Published in print: Jul 1, 2015
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