Experimental study of shear retrofit of RC beam-column joints using external post-tensioned bolts

Document Type : Research Article


1 Department of Civil Engineering, Faculty of Civil Engineering, Semnan University, Semnan, Iran

2 Associate Professor, Faculty of Civil Engineering, Semnan University, Iran

3 Professor, Faculty of Civil Engineering, University of Semnan


RC beam-column joints play a crucial role in transferring gravity and lateral loads from beam to column. By examining damaged buildings in recent earthquakes, RC beam-column joints are among the most vulnerable members of RC moment frames. Joint failure can pose a threat to the structure, ending up destroying the structure. The main type of failure of RC joints is shear failure due to the lack of transverse reinforcement and confinement in this area. The laboratory program of the current study suggests external post-tensioned bolts to retrofit RC joints. External post-tensioned bolts increase the confinement and enlargement of the joint panel zone and subsequently eliminate the deficient shear joints. Regarding the forces applied to the joint panel zone are implemented diagonally, the external post-tensioned bolts were used in two horizontal-vertical (HV) and diagonal (Di) patterns around the joint. The horizontal-vertical pattern was chosen owing to placing the resultants of the retrofit bolts forces in the direction of the applied forces. Furthermore, the diagonal pattern was adopted due to the placement of the retrofit bolts in the direction of the applied forces. The testing program includes four RC beam-column joint specimens with half-scale. One specimen was constructed as a standard criterion with all seismic requirements, and three specimens were made at the joint without implementing transverse reinforcement. One deficient specimen was used as a control specimen, and two specimens were subjected to cyclic loading after retrofitting by the proposed patterns. In order to investigate the effect of the proposed method, parameters such as; the force-displacement hysteresis response, energy absorption and damping value of the specimens were considered. The test results confirm the significant effect of the retrofit system against seismic loading. Accordingly, the failure was exited from the joint panel zone and transferred to the beam in retrofitted specimens. The final capacity of the retrofitted specimens increased by nearly 50% and their energy absorption by about 200%. In addition, the damping values and the ductility factors increased by about 100% and 32% in retrofitted specimens, respectively.


Main Subjects

[1] P. Cheung, T. Paulay, R. Park, New Zealand tests on full-scale reinforced concrete beam-column-slab subassemblages designed for earthquake resistance, Special Publication, 123 (1991) 1-38.
[2] R.P. Dhakal, T.-C. Pan, P. Irawan, K.-C. Tsai, K.-C. Lin, C.-H. Chen, Experimental study on the dynamic response of gravity-designed reinforced concrete connections, Engineering Structures, 27(1) (2005) 75-87.
[3] J. Kim, J.M. LaFave, Key influence parameters for the joint shear behaviour of reinforced concrete (RC) beam–column connections, Engineering structures, 29(10) (2007) 2523-2539.
[4] S. Alavi-Dehkordi, D. Mostofinejad, P. Alaee, Effects of high-strength reinforcing bars and concrete on seismic behavior of RC beam-column joints, Engineering Structures, 183 (2019) 702-719.
 [5] N.W. Hanson, H.W. Conner, Seismic resistance of reinforced concrete beam-column joints, Journal of the Structural Division, 93(5) (1967) 533-560.
[6] A.L. PARME, Recommendations for Design of Beam-Column Joints in Monolithic Reinforced Concrete Structures, ACI JOURNAL,  (1976) 375.
[7] R. Park, T. Paulay, Reinforced concrete structures, John Wiley & Sons, 1975.
[8] O. Rezaifar, M. Nazari, M. Gholhaki, Experimental study of rigid beam-to-box column connections with types of internal/external stiffeners, Steel and Composite Structures, 25(5) (2017) 535-544.
[9] O. Rezaifar, A. Younesi, Experimental study discussion of the seismic behavior on new types of internal/external stiffeners in rigid beam-to-CFST/HSS column connections, Construction and Building Materials, 136 (2017) 574-589.
[10] A.-D.G. Tsonos, Performance enhancement of R/C building columns and beam–column joints through shotcrete jacketing, Engineering Structures, 32(3) (2010) 726-740.
[11] M.K. Sharbatdar, A. Kheyroddin, E. Emami, Cyclic performance of retrofitted reinforced concrete beam–column joints using steel prop, Construction and Building Materials, 36 (2012) 287-294.
[12] Y.-R. Dong, Z.-D. Xu, Q.-Q. Li, Y.-S. Xu, Z.-H. Chen, Seismic behavior and damage evolution for retrofitted RC frames using haunch viscoelastic damping braces, Engineering Structures, 199 (2019) 109583.
[13] R. Sharma, P.P. Bansal, Behavior of RC exterior beam column joint retrofitted using UHP-HFRC, Construction and Building Materials, 195 (2019) 376-389.
[14] Y. Yang, Y. Xue, N. Wang, Y. Yu, Experimental and numerical study on seismic performance of deficient interior RC joints retrofitted with prestressed high-strength steel strips, Engineering Structures, 190 (2019) 306-318.
[15] Z.-Y. Zhang, R. Ding, X. Nie, J.-S. Fan, Seismic performance of a novel interior precast concrete beam-column joint using ultra-high performance concrete, Engineering Structures, 222 (2020) 111145.
[16] D. Mostofinejad, M. Hajrasouliha, Shear retrofitting of corner 3D-reinforced concrete beam-column joints using externally bonded CFRP reinforcement on grooves, Journal of Composites for Construction, 22(5) (2018) 04018037.
[17] D. Mostofinejad, A. Akhlaghi, Experimental investigation of the efficacy of EBROG method in seismic rehabilitation of deficient reinforced concrete beam–column joints using CFRP sheets, Journal of Composites for Construction, 21(4) (2017) 04016116.
[18] D. Mostofinejad, M. Hajrasouliha, 3D beam–column corner joints retrofitted with X-shaped FRP sheets attached via the EBROG technique, Engineering Structures, 183 (2019) 987-998.
[19] E. Emami, A. Kheyroddin, O. Rezaifar, Experimental Study of Eccentricity and Width to Thickness Ratio Effects of Arched Steel Haunches on Cyclic Behavior, Amirkabir Journal of Civil Engineering,  (2022). (in Persian)
[20] R. Morshed, E. Tavasoli, M. Barzegar, E‌x‌p‌e‌r‌i‌m‌e‌n‌t‌a‌l I‌n‌v‌e‌s‌t‌i‌g‌a‌t‌i‌o‌n o‌n S‌h‌e‌a‌r S‌t‌r‌e‌n‌g‌t‌h‌e‌n‌i‌n‌g o‌f R‌C B‌e‌a‌m‌s b‌y P‌r‌e‌s‌t‌r‌e‌s‌s‌e‌d E‌m‌b‌e‌d‌d‌e‌d T‌h‌r‌o‌u‌g‌h-s‌e‌c‌t‌i‌o‌n B‌a‌r‌s, Sharif Journal of Civil Engineering, 34(4.2) (2019) 102-110. (in Persian).
[21] E. Tavasoli, O. Rezaifar, A. Kheyroddin, Investigation of finite element retrofit of T-shaped reinforced concrete beam–column joints by external bolts, Amirkabir Journal of Civil Engineering,  (2021). (in Persian)
[22] A.C.I.A. Committee, Building Code Requirements for Structural Concrete ACI 318-19 and Commentary 318R–19, American Concrete Institute ACI Committee: Farmington Hills, MI, USA,  (2019).
[23] A. LRFD, Specification for structural steel buildings, American Institute of Steel Construction, Chicago, IL,  (2016).
[24] A.C.I.A. Committee, Guide for Testing Reinforced Concrete Structural Elements under Slowly Applied Simulated Seismic Loads (ACI 374.2R-13),  (2013).
[25] M. Priestley, R. Park, Strength and ductility of concrete bridge columns under seismic loading, Structural Journal, 84(1) (1987) 61-76.