Baseplate Rigidity and Anchorage Design

Abstract
The anchorage design with baseplates according to EN 1992-4 [1] and ACI 318 [2] postulates that the baseplates need to be sufficiently rigid, because the linear distribution of anchor forces is required for calculating the concrete failure resistance of anchor groups.
With the precondition that the baseplate is sufficiently rigid, a linear strain distribution under the baseplate is assumed in Eurocode [1] for calculating the anchor tension forces in the anchor group. But there are no workable provisions in [1] to check the required baseplate rigidity.
The research results about the stiffness criteria for rigid baseplate assumption in [3,4] confirm the statements in [5,6] that the linear strain assumption is unrealistic for normal baseplate thicknesses. That means, with normal baseplate thicknesses in the practice, the non-linear anchor tension force distribution will take place and has to be considered for the anchorage design. In this case, additional proofs to [1, 2] may be necessary in verifying the concrete failure resistance of anchor groups [3,4].
For anchor groups with narrow baseplate under shear load perpendicular to the long axis, there may be similar stiffness requirements on baseplate as for tension load.
In this paper, the rigid baseplate assumption for anchorage design is examined by calculation examples. The required thickness of baseplate to satisfy the linear strain assumption is studied by variation of tension load and bending moment. The proposed additional proof of anchor group resistance with non-linear anchor tension force distribution [3,4] is extensively verified by 40 test results. This additional proof is illustrated by design examples.
A realistic calculation model for baseplate under shear load is presented. A stiffness criterium for baseplate under shear load is proposed based on the calculation results of this model.

Keywords
anchorage design, baseplate rigidity, anchor stiffness, tension, shear, concrete failure

Cite this paper
Longfei Li, Baseplate Rigidity and Anchorage Design , SCIREA Journal of Civil Engineering and Building Construction . Volume 7, Issue 3, June 2022 | PP. 79-110. 10.54647/cebc56110

References

[ 1 ]	EN 1992-4 Eurocode 2 — Design of concrete structures — Part 4 Design of fastenings for use in concrete, 2018
[ 2 ]	ACI 318-14, American Concrete Institute ISBN:978-942727-11-8, March 2015
[ 3 ]	Li, L.: Required Thickness of Flexurally Rigid Baseplate for Anchor Fastenings, proceedings of fib Symposium Maastricht 2017, High Tech Concrete: Where Technology and Engineering Meet, DOI 10.1007/978-3-319-59471-2 109, © Springer International Publishing AG 2018
[ 4 ]	Li, L.: Bemessung von Befestigungen mit elastischen Ankerplatten unter Zug‐ und Biegebeanspruchung, Stahlbau 88, Heft 8, S. 762-774, © Ernst & Sohn Verlag 2019
[ 5 ]	Dae-Yong Lee, Subhash C. Goel and Bozidar Stojadinovic: Exposed Column-Base Plate Connections Bending About Weak Axis: I. Numerical Parametric Study: Steel Structures 8 (2008) 11-27
[ 6 ]	ACI 355: Seminar “Anchorage to Concrete”, page 163, Email Annex of Ronald A. Cook, Ph.D., P.E., F.ACI, F. ASCE, F.SEI, Professor Emeritus, Department of Civil Engineering University of Florida, 06 April 2017, Abstract from Page 163: Base Plate Flexibility, What needs to be considered • 1st - Plane sections do not remain plane - Beam theory is not correct
[ 7 ]	Li, L.: Software für herstellerunabhängige Ankerbemessung und wirklichkeitsnahe Berechnung von Ankerplatten, Bericht zu digitalen Planen und Bauen, Beton- und Stahlbetonbau 115 (2020), Heft 8
[ 8 ]	Li, L., Lotze, D., Stork: J. General method for calculating the anchor tension loads on a base plate, presentation on fib TG2.9, Paris September 2014
[ 9 ]	Li, L.: Relevant Anchor Stiffness for Design of Multiple Anchor Fastenings, presentation on fib TG2.9, Philadelphia, October 2016
[ 10 ]	Wald, F., Sokol, Z., Jaspart, J.P.: Base plate in bending and anchor bolts in tension, HERON Vol. 53 (2008) No. ½, P21-50
[ 11 ]	Block, K.: Behavior – Testing – Design, post installed anchors and anchor channels under fatigue loading, presentation on fib TG2.9, Berlin, November 2011
[ 12 ]	Lieberum, K.-H.: Das Tragverhalten von Beton bei extremer Teilflächenbelastung, Dissertation TH Darmstadt, 1987
[ 13 ]	Li, L., Stork,J.,Cook, R. A.: Calculation of anchor forces in multiple-anchor fastenings and the required stiffness of base plate, presentation on fib TG2.9, Kyoto May 2012
[ 14 ]	ACI 355.3R-11: Guide for Design of Anchorage to Concrete: Examples Using ACI 318 Appendix D, ISBN 978-0-87031-425-4, ACI May 2011
[ 15 ]	Required thickness for flexurally rigid base plate, Background and Design Proposal in the software Anchor Profi 2.5.0, Dr. Li Anchor Profi GmbH, March 2016
[ 16 ]	Li, L. Required Stiffness of Base Plates subjected to shear loading, fib T 2.9 Fastenings, Web meeting December 2021
[ 17 ]	MKT Metall-Kunststoff-Technik GmbH & Co. KG, Test records of shear tests M8-M24 wedge anchors and bonded anchors respectively, April 2021
[ 18 ]	EOTA TR029 Design of Bonded Anchors, Edition June 2007, EOTA, 1040 Brussels, Amended September 2010
[ 19 ]	ETAG 001, Annex C: DESIGN METHODS FOR ANCHORAGES, EOTA, 1040 Brussels, Amended October 2001
[ 20 ]	Technical specification CEN/TS 1992-4-2: Design of Fastenings for Use in Concrete, European Committee for Standardization, 2009
[ 21 ]	Bokor, B.; Sharma, A.; Hofmann, J.: Experimental investigations on concrete cone failure of rectangular and nonrectangular anchor groups. Engineering Structures, Vol. 188, 2019, pp. 202–217
[ 22 ]	Wunderlich, W., Hanenkamp, W.: Tragverhalten von Verankerungen mit Kopfbolzen- Versuchsserie 6.1 -6.4/6.7/5.5 Ankerplatten in Gruppenanordnung Berichts-Nr. A-04/85-06 Ruhr-Universität Bochum, September 1985
[ 23 ]	FMPA Stuttgart: Bericht über Belastungsversuche an einbetonierten Kopfbolzengruppen, Bericht II.4-14 151, 16. Mai 1983
[ 24 ]	Li, L., Li, Y.: Design of arbitrary anchor groups on concrete edge subjected to arbitrary shear load and torsional moment, SCIREA Journal of Civil Engineering and Building Construction, https://doi.org/10.54647/cebc56087, June 24, 2022
[ 25 ]	Third-party anchorage design software Anchor Profi 3.4.6, Dr. Li Anchor Profi GmbH, February, 2022