Rotational Stiffness of Deeply Embedded Column–Base Connections
Publication: Journal of Structural Engineering
Volume 143, Issue 8
Abstract
Deeply embedded column–base (DECB) connections comprise a steel column embedded into a concrete footing, and are common in mid-rise to high-rise steel moment resisting frames. These are often idealized as fixed or pinned in seismic simulations because validated models are not available to estimate their true stiffness; this results in highly erroneous simulations of structural response. A method to characterize the rotational stiffness of deeply embedded column–base connections is presented. The method reflects physical insights developed during a recent experimental program on DECB connections, while also retaining a degree of simplicity for application in practical settings. The method considers deformations of several components within the connection, including bending and shear deformations of the embedded column, in addition to bearing deformations of the concrete adjoining the embedment. To resolve the internal indeterminacies of stress distribution within the connection, the method relies on an adaptation of the Winkler beam theory, supplemented by empirical assumptions. The results are examined against nine full-scale experiments from two test programs, of which one focuses on DECB connections (with embedments in the range of 508–762 mm), whereas the other focuses on shallowly embedded column–base connections (embedments 203–406 mm). The method is reasonably accurate for all the test specimens, with an average test-predicted ratio of 1.20 with a coefficient of variation of 0.21. Limitations of the proposed approach are discussed.
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Acknowledgments
The authors are grateful to the American Institute of Steel Construction and the Charles Pankow foundation for funding the experiments on DECB connections, and The National Secretariat of Higher Education, Science, Technology, and Innovation of Ecuador (SENESCYT) whose graduate fellowship provided support for the lead author.
References
AISC. (2010). “Seismic provisions for structural steel buildings.”, Chicago.
AISC. (2011). Steel construction manual, 14th Ed., Chicago.
ASCE. (1994). “Guidelines for design of joints between steel beams and reinforced concrete columns.” J. Struct. Eng., 2330–2357.
ASCE. (1998). “Design guide for partially restrained composite connections.” J. Struct. Eng., 1099–1114.
Aviram, A., Stojadinovic, B., and Kiureghian, A. (2010). “Performance and reliability of exposed column base plate connections for steel moment-resisting frames.”, Pacific Earthquake Engineering Research Center, Berkeley, CA.
Barnwell, N. (2015). “Experimental testing of shallow embedded connections between steel columns and concrete footings.” Master’s thesis, Brigham Young Univ., Provo, UT.
Becker, J., and Bevis, M. (2004). “Love’s problem.” Geophys. J. Int., 156(2), 171–178.
Computers and Structures. (2015). CSI analysis reference manual for SAP2000, ETABS, SAFE, and CSiBridge, Berkeley, CA.
Cordova, P. P., and Deierlein, G. G. (2005). “Validation of the seismic performance of composite RCS frames: Full-scale testing, analytical modeling, and seismic design.”, John A. Blume Earthquake Engineering Center, Stanford, CA.
Fisher, J. M., and Kloiber, L. A. (2006). “Base plate and anchor rod design.” 2nd Ed., Steel design guide series No. 1, AISC, Chicago.
Gomez, I. R., Kanvinde, A. M., and Deierlein, G. G. (2010). “Exposed column base connections subjected to axial compression and flexure.”, AISC, Chicago.
Grauvilardell, J. E., Lee, D., Hajjar, J. F., and Dexter, R. J. (2005). “Synthesis of design, testing and analysis research on steel column base plate connections in high seismic zones.”, Dept. of Civil Engineering, Univ. of Minnesota, Minneapolis.
Grilli, D. A., and Kanvinde, A. M. (2015). “Embedded column base connections subjected to flexure and axial loads.”, Charles Pankow Foundation, Vancouver, WA.
Hetényi, M. (1946). Beams on elastic foundation: Theory with applications in the fields of civil and mechanical engineering, University of Michigan Press, Ann Arbor, MI.
Kanvinde, A. M., and Grilli, D. A. (2013). “Special moment frame base connection: Design example 8.” 2012 IBC SEAOC Structural/seismic design manual: Examples for Steel-Frame Buildings, Vol. 4, Structural Engineers Association of California, Sacramento, CA, 255–280.
Kanvinde, A. M., Grilli, D. A., and Zareian, F. (2012). “Rotational stiffness of exposed column base connections: Experiments and analytical models.” J. Struct. Eng., 549–560.
Krawinkler, H., Gupta, A., Medina, R., and Luco, N. (2000). “Loading histories for seismic performance testing of smrf components and assemblies.”, Applied Technology Council, Redwood City, CA.
Mattock, A. H., and Gaafar, G. H. (1981). “Strength of embedded steel sections as brackets.” ACI J., 79(2), 83–93.
Mazzoni, S., McKenna, F., Scott, M. H., and Fenves, G. L. (2009). “Open system for earthquake engineering simulation user command language manual, OpenSees version 2.0.” Pacific Earthquake Engineering Research Center, Univ. of California, Berkeley, CA.
Melchers, R. E. (1992). “Rotational stiffness of shallow footings.” Comput. Geotech., 13(1), 21–35.
Timoshenko, S. P. (1921). “On the correction factor for shear of the differential equation for transverse vibrations of bars of uniform cross-section.” Philos. Mag., 41(245), 744–746.
Trautner, C., Hutchinson, T., Grosser, P., and Silva, J. (2015). “Effects of detailing on the cyclic behavior of steel baseplate connections designed to promote anchor yielding.” J. Struct. Eng., .
Tryon, J. E., (2016). “Simple models for estimating the rotational stiffness of steel column to footing connections.” Master’s thesis, Brigham Young Univ., Provo, UT.
Zareian, F., and Kanvinde, A. M. (2013). “Effect of column base flexibility on the seismic safety of steel moment resisting frames.” Earthquake Spectra, 29(4), 1537–1559.
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Published In
Journal of Structural Engineering
Volume 143 • Issue 8 • August 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Jul 27, 2016
Accepted: Dec 21, 2016
Published ahead of print: Mar 20, 2017
Published online: Mar 21, 2017
Published in print: Aug 1, 2017
Discussion open until: Aug 21, 2017
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