Title:
Modifying the Concrete Breakout Area with a Bearing Plate to Change Capacity
Author(s):
Donald F. Meinheit
Publication:
Structural Journal
Volume:
119
Issue:
5
Appears on pages(s):
257-269
Keywords:
DOI:
10.14359/51734668
Date:
9/1/2022
Abstract:
In some instances, cast-in-place anchors need a little extra tension capacity in concrete breakout. One method of increasing capacity is to add a bearing plate at the embedded end of the anchor to increase the base area where the breakout cracking initiates. ACI 318-19 has a procedure for increasing the breakout area in Section 17.6.2.1.3. The American Association of State Highway and Transportation Officials (AASHTO) bridge code also has a procedure to design the bearing plates for post-tensioning anchors. These procedures have the same objective but yield different results. To effectively increase the breakout area, the bearing plate must be stiff enough to uniformly distribute the bearing stress to the concrete. This paper describes the analysis of previously published concrete
This paper describes the analysis of previously published concrete breakout test data and the implications the tests have on determining if the bearing plate is rigid enough to uniformly distribute the bearing stress to the concrete.
Related References:
1. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19),” American Concrete Institute, Farmington Hills, MI, 2019, 624 pp.
2. Shin, J.; Kim, J. H.; and Chang, H.-J., “Anchor Plate Effect on the Breakout Capacity in Tension for Thin-Walled Concrete Panels,” Engineering Structures, V. 106, 2016, pp. 147-153. doi: 10.1016/j.engstruct.2015.10.028
3. DeVries, R. A.; Jirsa, J. O.; and Bashandy, T., “Anchorage Capacity in Concrete of Headed Reinforcement with Shallow Embedments,” ACI Structural Journal, V. 96, No. 5, Sept.-Oct. 1999, pp. 728-736.
4. AASHTO, “LRFD Bridge Design Specifications,” ninth edition, American Association of State Highway and Transportation Officials, Washington, DC, 2020.
5. Hawkins, N. M., “The Bearing Strength of Concrete Loaded through Rigid Plates,” Magazine of Concrete Research, V. 20, No. 62, 1968, pp. 31-40 doi: 10.1680/macr.1968.20.62.31
6. Hawkins, N. M., “The Bearing Strength of Concrete Loaded through Flexible Plates,” Magazine of Concrete Research, V. 20, No. 63, 1968, pp. 95-102 doi: 10.1680/macr.1968.20.63.95
7. Roberts-Wollmann, C. L., and Breen, J. E., “Design and Test Specifications for Local Tendon Anchorage Zones,” ACI Structural Journal, V. 97, No. 6, Nov.-Dec. 2000, pp. 867-875.