Title:
Side-Face Blowout Strength of 43 and 57 mm (No. 14 and No. 18) Hooked Bars in Beam-Column Joints
Author(s):
Sungchul Chun, Min-Seo Bae, and Byung-Soo Lee
Publication:
Structural Journal
Volume:
114
Issue:
5
Appears on pages(s):
1227-1236
Keywords:
exterior beam-column joint; hooked bar; reinforcement; sideface blowout
DOI:
10.14359/51700804
Date:
9/1/2017
Abstract:
The confining effects of the cover and transverse reinforcement are excluded from the ACI 318 provisions on the development length of 43 and 57 mm (No. 14 and No. 18) hooked bars because of the absence of experimental evidence. Twenty-six simulated beamcolumn joint tests were therefore conducted using 43 and 57 mm (No. 14 and No. 18) hooked bars of 550 MPa (80,000 psi) yield strength in this study. The test variables include the embedment length, concrete compressive strength, side cover, and transverse reinforcement. An intentional side-face blowout failure occurred due to the prevention of the other failure modes. As the embedment length and side cover increased, the anchorage capacity of the hooked bars increased as well. By placing ties, the anchorage strength of the hooked bars increased, but a wide scattering of the improved strengths also occurred. At failure, the entire bar force was resisted by the hook bearing only, and the bond along the straight region of the hooked bars vanished. From regression analyses of 74 datasets, including Marques and Jirsa’s tests, a model is proposed for predicting the anchorage strength of hooked bars
terminated within exterior beam-column joints.
Related References:
1. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” American Concrete Institute, Farmington Hills, MI, 2014, 519 pp.
2. ACI Committee 349, “Code Requirement for Nuclear Safety-Related Concrete Structures (ACI 349-13) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2013, 196 pp.
3. ACI-ASME Joint Technical Committee, “Code for Concrete Containments,” The American Society of Mechanical Engineers, New York, NY, 2015, 188 pp.
4. Minor, J., and Jirsa, J. O., “Behavior of Bent Bar Anchorage,” ACI Journal Proceedings, V. 72, No. 4, Apr. 1975, pp. 141-149.
5. Marques, J. L. G., and Jirsa, J. O., “A Study of Hooked Bar Anchorages in Beam-Column Joints,” ACI Journal Proceedings, V. 72, No. 5, May 1975, pp. 198-209.
6. Pinc, R. L.; Watkins, M. D.; and Jirsa, J. O., “Strength of Hooked Bar Anchorages in Beam-Column Joints,” Department of Civil Engineering, Structures Research Laboratory, University of Texas at Austin, Austin, TX, 1977, 67 pp.
7. Johnson, L. A., and Jirsa, J. O., “The Influence of Short Embedment and Close Spacing on the Strength of Hooked Bar Anchorages,” Phil M. Ferguson Structural Engineering Laboratory, Department of Civil Engineering, University of Texas at Austin, Austin, TX, Apr. 1981, 93 pp.
8. Soroushian, P.; Obaseki, K.; Nagi, M.; and Rojas, M. C., “Pullout Behavior of Hooked Bars in Exterior Beam-Column Connections,” ACI Structural Journal, V. 85, No. 3, May-June 1988, pp. 269-276.
9. Hamad, B. S.; Jirsa, J. O.; and De Paulo, N. I. D., “Anchorage Strength of Epoxy-Coated Hooked Bars,” ACI Structural Journal, V. 90, No. 2, Mar.-Apr. 1993, pp. 210-217.
10. Joh, O., and Shibata, T., “Anchorage Behavior of 90-Degree Hooked Beam Bars in Reinforced Concrete Beam-Column Joints ” Eleventh World Conference on Earthquake Engineering, 1996, 8 pp.
11. Sperry, J.; Al-Yasso, S.; Searle, N.; DeRubeis, M.; Darwin, D.; O’Reilly, M.; Matamoros, A.; Feldman, L.; Lepage, A.; Lequesne, R.; and Ajaam, A., “Anchorage of High-Strength Reinforcing Bars with Standard Hooks,” SM Report No. 111, University of Kansas, Lawrence, KS, June 2015, 243 pp.
12. ASTM C39/C39M-14, “Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens,” ASTM International, West Conshohocken, PA, 2014, 7 pp.
13. Joint ACI-ASCE Committee 352, “Recommendations for Design of Beam-Column Connections in Monolithic Reinforced Concrete Structures (ACI 352R-02),” American Concrete Institute, Farmington Hills, MI, 2002, 37 pp.
14. ASTM A706-14, “Standard Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 2014, 7 pp.
15. ASTM A605-15, “Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 2015, 8 pp.
16. Furche, J., and Eligehausen, R., “Lateral Blow-Out Failure of Headed Studs Near a Free Edge,” Anchors in Concrete—Design and Behavior, SP-130, American Concrete Institute, Farmington Hills, MI, 1991, pp. 235-252.
17. Chun, S.-C.; Choi, C.-S.; and Jung, H.-S., “Side-Face Blowout Failure of large-Diameter High-Strength Headed Bars in Beam-Column Joints,” ACI Structural Journal, V. 114, No. 1, Jan.-Feb. 2017, pp. 161-172. doi: 10.14359/51689161
18. Joint ACI-ASCE Committee 408, “Suggested Development, Splice, and Standard Hook Provisions for Deformed Bars in Tension,” Concrete International, V. 1, No. 7, July 1979, pp. 44-46.
19. Eligehausen, R.; Mallée, R.; and Silva, J. F., Anchorage in Concrete Construction, Ernst & Sohn, Berlin, Germany, 2006, pp. 93-97.
20. Thompson, M. K.; Ziehl, M. J.; Jirsa, J. O.; and Breen, J. E., “CCT Nodes Anchored by Headed Bars—Part 1: Behavior of Nodes,” ACI Structural Journal, V. 102, No. 6, Nov.-Dec. 2005, pp. 808-815.
21. Thompson, M. K.; Ledesma, A.; Jirsa, J. O.; and Breen, J. E., “Lap Splices Anchored by Headed Bars,” ACI Structural Journal, V. 103, No. 2, Mar.-Apr. 2006, pp. 271-279.
22. Chun, S.-C., “Lap Splice Tests Using High-Strength Headed Bars of 550 MPa (80 ksi) Yield Strength,” ACI Structural Journal, V. 112, No. 6, Nov.-Dec. 2015, pp. 679-688. doi: 10.14359/51687936
23. Nielsen, M. P., Limit Analysis and Concrete Plasticity, second edition, CRC Press LLC, Boca Raton, FL, 1999, 908 pp.
24. Draper, N. R., and Smith, H., Applied Regression Analysis, second edition, Wiley, New York, 1981, 709 pp.
25. Natrella, M. G., Experimental Statistics, National Bureau of Standards Handbook 91, U.S. Department of Commerce, Washington, DC, 1966, pp. 13-15 of Chapter 2.