The anchorage headed bars is widely applied in many modern concrete structures. The existing design provision of anchorage headed bars is limited to range normal-strength materials and has different design approachment based on vary failure modes. The design code for application headed bar of beam-column joints is still not provided. Thus, a study is intended to evaluate the mechanical behavior of the headed bars in the joint to enrich reference for every design engineer of High Strength Reinforced Concrete (HSRC) for “New RC” Taiwan Project.
12 (twelve) exterior beam-column joint specimens designed based on ACI 318-14 code tested into an experimental program to investigate the critical failure mode. All of the final failure conditions observed are the same with typical side-face blowout failure mode. The numerical model built and verified by experimental result. Afterward, an extensive assessment of a total of 108 specimens using ANSYS simulation conducted to evaluate the effect of the concrete compressive strength, the yield strength reinforcement, the diameter of bar, and thickness concrete clear cover. It found that increasing thickness concrete cover ≥ 1.5db is the most effective way to avoid side-face blowout failure mode. Increment of concrete compressive strength and lowering yield strength bar could slightly increase capacity. On the other hand, increasing diameter rebar shall decrease the capacity.
Moreover, the evaluation of the various capacity equations proposed by previous researchers conducted to prevent the side-face blowout failure of exterior beam-column joints. The model suggested by Chun et al. (2018) gives the most reliable and conservative formulation to predict the anchorage capacity. Meanwhile, the predicting anchorage stress capacity by code provision of ACI 318-14 has overestimated the anchorage capacity with the increment of concrete compressive strength. 2.5 % is the average increment rate of anchorage capacity headed bars at the exterior beam-column joint from 70 MPa to 100 MPa of HSRC.

The anchorage headed bars is widely applied in many modern concrete structures. The existing design provision of anchorage headed bars is limited to range normal-strength materials and has different design approachment based on vary failure modes. The design code for application headed bar of beam-column joints is still not provided. Thus, a study is intended to evaluate the mechanical behavior of the headed bars in the joint to enrich reference for every design engineer of High Strength Reinforced Concrete (HSRC) for “New RC” Taiwan Project.
12 (twelve) exterior beam-column joint specimens designed based on ACI 318-14 code tested into an experimental program to investigate the critical failure mode. All of the final failure conditions observed are the same with typical side-face blowout failure mode. The numerical model built and verified by experimental result. Afterward, an extensive assessment of a total of 108 specimens using ANSYS simulation conducted to evaluate the effect of the concrete compressive strength, the yield strength reinforcement, the diameter of bar, and thickness concrete clear cover. It found that increasing thickness concrete cover ≥ 1.5db is the most effective way to avoid side-face blowout failure mode. Increment of concrete compressive strength and lowering yield strength bar could slightly increase capacity. On the other hand, increasing diameter rebar shall decrease the capacity.
Moreover, the evaluation of the various capacity equations proposed by previous researchers conducted to prevent the side-face blowout failure of exterior beam-column joints. The model suggested by Chun et al. (2018) gives the most reliable and conservative formulation to predict the anchorage capacity. Meanwhile, the predicting anchorage stress capacity by code provision of ACI 318-14 has overestimated the anchorage capacity with the increment of concrete compressive strength. 2.5 % is the average increment rate of anchorage capacity headed bars at the exterior beam-column joint from 70 MPa to 100 MPa of HSRC.

ACI Committee 318. (2014). Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14). American Concrete Institute, Farmington Hills, MI., 519 pp.
ACI Committee 318. (2019). Building Code Requirements for Structural Concrete (ACI 318-19) – Public Discussion Draft. American Concrete Institute, Farmington Hills, MI., 988 pp.
ACI Committee 352. (2010). Recommendations for Design of Beam-Column Connections in Monolithic Reinforced Concrete Structures.
ASTM A970/A970M-15. (2015). Standard Specification for Headed Steel Bars for Concrete Reinforcement. West Conshohocken, PA., 9 pp.
Bashandy, T. R. (1996). Application of Headed Bars in Concrete Members. PhD Dissertation, University of Texas at Austin, Austin, Tex., 299 pp.
Brooker, O. (2013). Use of Headed Bars as Anchorage to Reinforcement. The Structural Engineer, 91(9), 49-57.
Carreira, D. J., Chu, K. H. (1986). Stress-strain Relationship for Reinforced Concrete in Tension. ACI Journal, 83(3), 21-28.
Chun, S.-C., Choi, C.-S., Jung, H.-S. (2017). Side-Face Blowout Failure of Large-Diameter High-Strength Headed Bars in Beam-Column Joints. ACI Structural Journal, 114 (1), 161-172.
DeVries, R. A. (1996). Anchorage of Headed Reinforcement in Concrete. PhD Dissertation, University of Texas at Austin, Austin, Tex., 299 pp.
Eligehausen, R., Mallée, R., Silva, J. F. (2006). Anchorage in Concrete Construction. Ernst & Sohn, Berlin, Germany.
Fuchs, W., Eligehausen, R., Breen, J. E. (1995). Concrete Capacity Design (CCD) Approach for Fastening to Concrete. ACI Structural Journal, 92 (1), 73-94.
Furche, J. and Eligehausen, R. (1991). Lateral Blow-out Failure of Headed Studs Near a Free Edge. Anchor in Concrete-Design and Behavior, SP-130. American Concrete Institute, Farmington Hills, MI., 235-252.
Intan, R. P. (2018). Study on the Strength Development of Side-Face Blowout Failure Modee for High-Strength Reinforcements in B/C Joints. Master Thesis, NTUST.
Kohnke, P. (1999). ANSYS Theory Reference - Release 5.6. Retrieved from http://research.me.udel.edu/~lwang/teaching/MEx81/ansys56manual.pdf.
Lin, K. C. (2015). Research Progresses on Taiwan New RC Project. NCREE newsletter, 10(2).
Shao, Y., Darwin, D., O’Reilly, M., Lequesne, R. D., Ghimire, K., and Hano, M. (2016). Anchorage of Conventional and High-Strength Headed Reinforcing Bars. SM Report No. 117, University of Kansas for Research, Inc., Lawrence, KS, 234 pp.
Thompson, M. K., Ziehl, M. J., Jirsa, J. O., and Breen, J. E. (2006). Behavior and Capacity of Headed Reinforcement. ACI Structural Journal, 103(4), 522-530.
Thompson, M. K., Ziehl, M. J., Jirsa, J. O., and Breen, J. E. (2005). CCT Nodes Anchored by Headed Bars - Part 1: Behavior of Nodes. ACI Structural Journal, 102 (6), 808-815.
Thompson, M. K., Ziehl, M. J., Jirsa, J. O., and Breen, J. E. (2005). CCT Nodes Anchored by Headed Bars - Part 2: Capacity of Nodes. ACI Structural Journal, 103 (1), 65-74.
Sim, H.-J., Chun, S.-C., Choi, S., Yu, E. (2018). Headed Bars in Simulated Exterior Beam-Column Joints of UHPFRC. Magazine of Concrete Research, 70(19), 1016-1026.
Wee, T. H., Chin, M. S., Mansur, M. A. (1996). Stress-strain Relationship of High-Strength Concrete in Compression. Journal of Materials in Civil Engineering, 8(2), 70-76.