Efficiency of Externally Bonded L-Shaped FRP Laminates in Strengthening Reinforced-Concrete Interior Beam-Column Joints
Publication: Journal of Composites for Construction
Volume 20, Issue 3
Abstract
This study investigated the efficiency of externally bonded L-shaped fiber-reinforced polymer (FRP) laminates in strengthening seismically damaged reinforced concrete (RC) interior joints. Ten ½-scale interior beam-column joints, including two reference specimens, were constructed and then damaged under simulated cyclic lateral loads. In addition to repairing visual cracks with epoxy injections, four of eight specimens were strengthened with externally bonded L-shaped carbon fiber–reinforced polymer (CFRP) laminates and the rest were strengthened with basalt fiber–reinforced polymer (BFRP) laminates. Retesting after retrofitting showed that the average peak strength of the CFRP-strengthened and BFRP-strengthened specimens increased by approximately 20 and 10%, respectively. The two strengthening systems also clearly enhanced the deformability of the specimens. Further analysis indicated strength increase was controlled by the end debonding of FRP laminates near critical sections of the specimens, thus the bending strengthening formulas, which were extensively used in practice, overestimated the strengthening efficiency. To solve this problem, alternative formulas accounting for the end debonding of FRP were proposed to predict the peak strength and FRP strain of the specimens. The predictions showed acceptable agreement with the test results, demonstrating the proposed formulas were applicable to predict the efficiency of externally bonded L-shaped FRPs in strengthening damaged interior framed joints.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors are grateful for the financial support received from the National Science Funds of China (Project Nos. 51478362, 51378397, and 51408436) and the Open Project Program of the Key Laboratory of Structure Engineering of Shanghai (Project No. 2013-KF03).
References
ACI (American Concrete Institute). (2005). “Building code requirements for structural concrete and commentary.” ACI 318M-05, Farmington Hills, MI.
ACI (American Concrete Institute). (2008). “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures.” ACI 440.2R-08, Farmington Hills, MI.
Alcocer, S. M., and Jirsa, J. O. (1993). “Strength of reinforced concrete frame connections rehabilitated by jacketing.” ACI Struct. J., 90(3), 249–261.
Antonopoulos, C., and Triantafillou, T. C. (2003). “Experimental investigation of FRP-strengthened RC beam-column joints.” J. Compos. Constr., 39–49.
Bousselham, A. (2010). “State of research on seismic retrofit of RC beam-column joints with externally bonded FRP.” J. Compos. Constr., 49–61.
Chajes, M. J., Finch, W. W., Jr., Januszka, T. F., and Thonson, T. A., Jr. (1996). “Bond and force transfer of composite-material plates bonded to concrete.” ACI Struct. J., 93(2), 295–303.
Chen, G. M., Teng, J. G., and Chen, J. F. (2012). “Process of debonding in RC beams shear-strengthened with FRP U-strips or side strips.” Int. J. Solids Struct., 49(10), 1266–1282.
Chen, J. F., and Teng, J. G. (2001). “Anchorage strength models for FRP and steel plates attached to concrete.” J. Struct. Eng., 784–791.
Cui, J. Y., Sun, J. A., and Song, Y. P. (2008). “Experimental study on shear resistant capacity of reinforced concrete frame corner joints.” J. Earthquake Eng. Eng. Vib., 28(5), 115–121 (in Chinese).
El-Amoury, T., and Ghobarah, A. (2002). “Seismic rehabilitation of beam-column joint using GFRP sheets.” Eng. Struct., 24(11), 1397–1407.
GB50011-2001. (2001). “Code for seismic design of buildings.” China Architecture and Building Press, Beijing.
Gergely, J., Pantelides, C. P., and Reaveley, L. D. (1998). “Shear strengthening of bridge joints with carbon fiber composites.” Proc., 6th US National Conf. on Earthquake Engineering, EERI, Oakland, CA.
Gergely, J., Pantelides, C. P., and Reaveley, L. D. (2000). “Shear strengthening of RCT-joints using CFRP composites.” J. Compos. Constr., 56–64.
Ghobarah, A., Aziz, T. S., and Biddah, A. (1997). “Rehabilitation of reinforced concrete frame connections using corrugated steel jacketing.” ACI Struct. J., 94(3), 282–294.
Ghobarah, A., and El-Amoury, T. (2005). “Seismic rehabilitation of deficient exterior concrete frame joints.” J. Compos. Constr., 408–416.
Ghobarah, A., and Saatcioglu, M. (2006). “The impact of the 26 December 2004 earthquake and tsunami on structures and infrastructure.” Eng. Struct., 28(2), 312–326.
Ghobarah, A., and Said, A. (2001). “Seismic rehabilitation of beam-column joints using FRP laminates.” J. Earthquake Eng., 5(1), 113–129.
Ghobarah, A., and Said, A. (2002). “Shear strengthening of beam-column joint.” Eng. Struct., 24(7), 881–888.
Granata, P. J., and Parvin, A. (2001). “An experimental study on kevlar strengthening of beam-column connections.” Compos. Struct., 53(2), 163–171.
Hakuto, S., Park, R., and Tanaka, H. (2000). “Seismic load tests on interior and exterior beam-column joints with substandard reinforcing details.” ACI Struct. J., 97(1), 11–25.
Karayannis, C. G., and Sirkelis, G. M. (2008). “Strengthening and rehabilitation of RC beam-column joints using carbon-FRP jacketing and epoxy resin injection.” Earthquake Eng. Struct. Dyn., 37(5), 769–790.
Kitayama, K., Otani, S., and Aoyama, H. (1987). “Earthquake resistant design criteria for reinforced concrete interior beam-column joints.” Proc., Pacific Conf. on Earthquake Eng., PEER, CA.
Le-Trung, K., Lee, K., and Lee, J. (2010). “Experimental study of RC beam-column joints strengthened using CFRP composites.” Composites Part B, 41(1), 76–85.
Li, J., Samali, B., Ye, L., and Bakoss, S. (2002). “Behavior of concrete beam-column connections reinforced with hybrid FRP sheet.” Compos. Struct., 57(1–4), 357–365.
Lu, Z. D., Su, L., and Yu, J. T. (2011). “Experimental study on the seismic behaviour of strengthened concrete column-beam joints by simulated earthquake.” Procedia Eng., 14, 1871–1878.
Maeda, T., Asano, Y., Sato, Y., Ueda, T., and Kakuta, Y. (1997). “A study on bond mechanism of carbon fiber sheet.”, Japan Concrete Institute, Tokyo.
Masi, A., Santarsiero, G., Lignola, G. P., and Verderame, G. M. (2013). “Study of the seismic behavior of external RC beam-column joints through experimental tests and numerical simulations.” Eng. Struct., 52, 207–219.
Mukherjee, A., and Joshi, M. (2005). “FRPC reinforced concrete beam-column joints under cyclic excitation.” Compos. Struct., 70(2), 185–199.
Pantelides, C., Clyde, C., and Dreaveley, L. (2000). “Rehabilitation of R/C building joints with FRP composites.” Proc., 12th World Conf. on Earthquake Eng., New Zealand Society for Earthquake Engineering, Wellington, New Zealand.
Pantelides, C. P., Okahashi, Y., and Reaveley, L. D. (2008). “Seismic rehabilitation of reinforced concrete frame interior beam-column joints with FRP composites.” J. Compos. Constr., 435–445.
Prota, A., and Nanni, A. (2004). “Selective upgrade of underdesigned reinforced concrete beam-column joints using carbon fiber-reinforced polymers.” ACI Struct. J., 101(5), 699–707.
Sezen, H., Whittaker, A. S., Elwood, K. J., and Mosalam, K. M. (2003). “Performance of reinforced concrete buildings during the August 17, 1999 Kocaeli, Turkey earthquake, and seismic design and construction practice in Turkey.” Eng. Struct., 25(1), 103–114.
Täljsten, B. (1997). “Defining anchor lengths of steel and CFRP plates bonded to concrete.” Int. J. Adhes. Adhes., 17(4), 319–327.
Tastani, S. P, Thermou, G. E., and Pantazopoulou, S. J. (2012). “Deformation analysis of reinforced concrete columns after repair with FRP jacketing.” 15th World Conf. on Earthquake Eng., IAEE, Tokyo.
Tastani, S. P., and Pantazopoulou, S. J. (2013). “Yield penetration in seismically loaded anchorages: Effects on member deformation capacity.” Earthquakes Struct., 5(5), 527–552.
Teng, J. G., and Chen, J. F. (2005). FRP strengthened RC structures, China Architecture & Build Press, Beijing (in Chinese).
Tsonos, A. D. G. (2010). “Performance enhancement of R/C building columns and beam-column joints.” Eng. Struct., 32(3), 726–740.
Tsonos, A. G. (1999). “Lateral load response of strengthened reinforced concrete beam-to-column joints.” ACI Struct. J., 96(1), 46–56.
Wang, G. L., Dai, J. G., and Teng, J. G. (2012). “Shear strength model for RC beam-column joints under seismic loading.” Eng. Struct., 40, 350–360.
Wang, Y. Y. (2008). “Lessons learned from the “5.12” Wenchuan earthquake: Evaluation of earthquake performed objectives and the importance of seismic conceptual design principles.” Earthquake Eng. Eng. Vib., 7(3), 255–262.
Ye, L. P., and Qu, Z. (2008). “Study on ensuring the strong column-weak beam mechanism for RC frames based on the damage analysis in the Wenchuan earthquake.” Build. Struct., 38(11), 52–67 (in Chinese).
Yuan, H., Wu, Z., and Yoshizawa, H. (2001). “Theoretical solutions on interfacial stress transfer of externally bonded steel/composite laminates.” Proc. JSCE, 2001(675), 27–39.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 20 • Issue 3 • June 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Nov 28, 2014
Accepted: Jul 22, 2015
Published online: Oct 9, 2015
Discussion open until: Mar 9, 2016
Published in print: Jun 1, 2016
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.