Seismic performance of FRP-strengthened RC joints by applying bond effects of concrete-FRP interface

Document Type : Research Article


1 Faculty of Engineering, Kharazmi University, Tehran , Iran

2 Faculty of Engineering, Kharazmi University, Tehran, Iran.


In this research, using the nonlinear finite element method, a numerical study has been performed on the seismic behavior of the deficient RC beam-column joints (with non-seismic detailing), and the seismic rehabilitation of these joints by using FRP composite laminates. At first, based on previous experimental studies, a series of RC joint specimens were considered to verify the proposed numerical model. This series of specimens include six RC interior joint specimens with non-seismic detailing and retrofitted with FRP laminates under cyclic loading. Comparison between the load-displacement curves obtained from the numerical model with corresponding experimental data shows that the proposed model is capable to high accurately predict the response of RC joints under cyclic loading. Then, based on the verified model, the performance of two-dimensional (2-D) deficient and strengthened exterior RC joint, three-dimensional (3-D) interior and exterior RC joints with considering the effect of the slab and beam perpendicular to the plane of the frame and also strengthening of (3-D) RC joints with focusing on the behavior of the FRP to the concrete interface is evaluated. It was observed that the failure mode of the retrofitted RC exterior specimens, unlike the deficient specimens, is the formation of the plastic hinge in the beam section. In addition, it is seen that the slab and the lateral beam have a significant effect on the performance of deficient joints, which can increase the resistance of the 3-D specimens by more than 20%; also, in 3D strengthened joints, the possibility of debonding of FRP laminates from concrete is higher than the 2-D model.


Main Subjects

[1] E. Zamani Beydokhti, H. Shariatmadar, Strengthening and rehabilitation of exterior RC beam–column joints using carbon-FRP jacketing, Materials and Structures, 49(12) (2016) 5067-5083.
[2] S.K. Ghomi, E. El-Salakawy, Seismic Performance of GFRP-RC Exterior Beam-Column Joints with Lateral Beams, Journal of Composites for Construction, 20(1) (2016) 04015019.
[3] C.D. Vecchio, M.D. Ludovico, A. Balsamo, A. Prota, G. Manfredi, M. Dolce, Experimental Investigation of Exterior RC Beam-Column Joints Retrofitted with FRP Systems, Journal of Composites for Construction, 18(4) (2014) 04014002.
[4] C. Del Vecchio, M. Di Ludovico, A. Prota, G. Manfredi, Analytical model and design approach for FRP strengthening of non-conforming RC corner beam–column joints, Engineering Structures, 87 (2015) 8-20.
[5] E. Esmaeeli, F. Danesh, K.F. Tee, S. Eshghi, A combination of GFRP sheets and steel cage for seismic strengthening of shear-deficient corner RC beam-column joints, Composite Structures, 159 (2017) 206-219.
[6] A. R‌e‌z‌a S‌a‌t‌t‌a‌r‌i, M. K‌a‌z‌e‌m S‌h‌a‌r‌b‌a‌t‌d‌a‌r, A. D‌a‌l‌v‌a‌n‌d, E‌xperimental S‌tudy on S‌trengthening of R‌C C‌onnections with F‌R‌P S‌heets by E‌mbedding Surface G‌rooves, Sharif Journal of Civil Engineering, 31.2(1.2) (2015) 41-50, (In persian).
[7] 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.
[8] H. Shariatmadar, E. Zamani Beydokhti, Experimental and analytical investigation of damaged concrete beam-column joints strengthened by CFRP composites, Modares Civil Engineering journal, 16(20) (2017) 65-77, (In persian).
[9] J. Yu, X. Shang, Z. Lu, Efficiency of Externally Bonded L-Shaped FRP Laminates in Strengthening Reinforced-Concrete Interior Beam-Column Joints, Journal of Composites for Construction, 20(3) (2016) 04015064.
[10] C. Ma, D. Wang, Z. Wang, Seismic retrofitting of full-scale RC interior beam-column-slab subassemblies with CFRP wraps, Composite Structures, 159 (2017) 397-409.
[11] K. Allam, A.S. Mosallam, M.A. Salama, Experimental evaluation of seismic performance of interior RC beam-column joints strengthened with FRP composites, Engineering Structures, 196 (2019) 109308.
[12] H. Toutanji, P. Saxena, L. Zhao, T. Ooi, Prediction of Interfacial Bond Failure of FRP-Concrete Surface, Journal of Composites for Construction, 11(4) (2007) 427-436.
[13] K. Le-Trung, K. Lee, J. Lee, D.H. Lee, S. Woo, Experimental study of RC beam–column joints strengthened using CFRP composites, Composites Part B: Engineering, 41(1) (2010) 76-85.
[14] R.A. Hawileh, M.Z. Naser, J.A. Abdalla, Finite element simulation of reinforced concrete beams externally strengthened with short-length CFRP plates, Composites Part B: Engineering, 45(1) (2013) 1722-1730.
[15] F. Bencardino, A. Condello, SRG/SRP–concrete bond–slip laws for externally strengthened RC beams, Composite Structures, 132 (2015) 804-815.
[16] E. Monaldo, F. Nerilli, G. Vairo, Effectiveness of some technical standards for debonding analysis in FRP-concrete systems, Composites Part B: Engineering, 160 (2019) 254-267.
[17] J. Lubliner, J. Oliver, S. Oller, E. Oñate, A plastic-damage model for concrete, International Journal of Solids and Structures, 25(3) (1989) 299-326.
[18] J. Lee, G.L. Fenves, Plastic-Damage Model for Cyclic Loading of Concrete Structures, Journal of Engineering Mechanics, 124(8) (1998) 892-900.
[19] ABAQUS/CAE, Analysis User's Manual Version 6.13, Dassault Systems Similia Corp.,  (2013).
[20] Saenz L.P, Discussion of Paper by Desai, Krishnan S, Equation for stress-strain curve of concrete, ACI, 61(8) (1964) 1229-1235.
[21] P.H. Bischoff, R. Paixao, Tension stiffening and cracking of concrete reinforced with glass fiber reinforced polymer (GFRP) bars, Canadian Journal of Civil Engineering, 31(4) (2004) 579-588.
[22] American Concrete Institute (ACI), Building code requirements for structural concrete and commentary, ACI Committee 318, ACI318-14,  (2014).
[23] L. Qingfu, G. Wei, K. Yihang, Parameter calculation and verification of concrete plastic damage model of ABAQUS, in:  IOP Conference Series: Materials Science and Engineering, IOP Publishing, 2020, pp. 012036.
[24] Z. Hashin, Failure Criteria for Unidirectional Fiber Composites, Journal of Applied Mechanics, 47(2) (1980) 329-334.
[25] Z. Hashin, A. Rotem, A Fatigue Failure Criterion for Fiber Reinforced Materials, Journal of Composite Materials, 7(4) (1973) 448-464.
[26] I. Lapczyk, J.A. Hurtado, Progressive damage modeling in fiber-reinforced materials, Composites Part A: Applied Science and Manufacturing, 38(11) (2007) 2333-2341.
[27] Federation International du Beton. Fib Model Code 2010 - Final draft (bulletins 65 and 66),  (2012).
[28] M. Ridha, V.B.C. Tan, T.E. Tay, Traction–separation laws for progressive failure of bonded scarf repair of composite panel, Composite Structures, 93(4) (2011) 1239-1245.
[29] N. Kishi, G. Zhang, H. Mikami, Numerical Cracking and Debonding Analysis of RC Beams Reinforced with FRP Sheet, Journal of Composites for Construction, 9(6) (2005) 507-514.
[30] H.Y. Omran, R. El-Hacha, Nonlinear 3D finite element modeling of RC beams strengthened with prestressed NSM-CFRP strips, Construction and Building Materials, 31 (2012) 74-85.
[31] CNR-DT 200 R1/2013, Guide for the design and construction of externally bonded FRP systems for strengthening existing structures – materials, RC and PC structures, masonry structures, Italian National Research council, Rome, Italy, 2013.
[32] American Concrete Institute (ACI). Building code requirements for structural concrete. ACI Committee 318,  (1963).
[33] D.I. Kachlakev, T.H. Miller, T. Potisuk, S.C. Yim, K. Chansawat, Finite element modeling of reinforced concrete structures strengthened with FRP laminates, Oregon. Dept. of Transportation. Research Group, 2001.
[34] I.M. Daniel, O. Ishai, Engineering mechanics of composite materials, 2 ed., Oxford university press, New York, 2006.
[35] S. Ghafarizadeh, J.-F. Chatelain, G. Lebrun, Finite element analysis of surface milling of carbon fiber-reinforced composites, The International Journal of Advanced Manufacturing Technology, 87(1) (2016) 399-409.
[36] American Concrete Institute (ACI). Guide for design and construction of externally bonded FRP systems for strengthening concrete structures. ACI Committee 440,  (2008).
[37] International Code Council Evaluation Service (ICC-ES) Acceptance Criteria AC125. Acceptance criteria for concrete and reinforced and unreinforced masonry strengthening using externally bonded Fiber-Reinforced Polymer (FRP) composite systems, Brea, CA, USA,  (2017).