Cyclic Evaluation of Severely Damaged RC Frames Repaired and Strengthened through FRP-Wrapped Coupler-Box Confinement
Publication: Journal of Composites for Construction
Volume 26, Issue 3
Abstract
The present study is focused on the retrofitting solution and its verification through experimental investigation for the two most common catastrophic modes of failure in reinforced concrete (RC) frame buildings, namely, buckling of reinforcing bars in the plastic hinge region of columns and shear failure of beam–column joints. The first mode of failure is retrofitted with interlinked coupler-box assemblies, while the second mode is repaired with external carbon fiber–reinforced polymer (CFRP) wrapping. The efficiency of the proposed retrofitting technique is evaluated by the hysteresis behavior, failure mechanism, and performance index parameters of the re-established frame, which are compared with the results of the initially tested bare frame. The recommended mechanism restricts the restored frame section against any possible movement or rotation and helps by a subsequent shift in yield location. The prime advantage of the proposed technique is that it prevents the possible slip of rebar from the sleeve, which is intercepted by the interlinking process, and eliminates the formation of inclined shear cracks at beam–column joints restricted by externally wrapped CFRP composites. The synergic effect of coupler-box and CFRP enhances the overall performance of the re-established frame by keeping the frame sections intact even after a lateral drift of 6%, which is relatively higher than the collapse prevention drift level, i.e., 4% as per FEMA guidelines. The obtained test results reveal the capability of CFRP and coupler-box assemblage as a possible futuristic approach for retrofitting outmoded RC building frames, in which buckling in longitudinal rebars of columns at their respective plastic hinge locations is inevitable.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors acknowledge the research funding received from the Ministry of Earth Sciences, New Delhi, India (MoE-1274-EQD).
Notation
The following symbols are used in this paper:
- Afrp,j
- cross-sectional area of a CFRP wrap crossing the joint;
- bj
- breadth of the beam–column joint;
- D
- column dimension in the loading direction;
- dj
- depth of the beam–column joint;
- Efrp
- elastic modulus of the CFRP laminate;
- ffrp
- ultimate unidirectional tensile strength of the composite;
- ffrp,deb.
- debonding stress in FRP;
- fh
- confining pressure provided by transverse steel reinforcement;
- fl
- lateral clamping pressure over the lap-splice length;
- fy
- yield stress of the reinforcing bars;
- compressive strength of confined concrete;
- Lc
- length of the coupler sleeve;
- tc
- wall thickness of the coupler sleeve;
- tfrp,c
- design thickness of the CFRP laminate near the column hinge;
- tfrp,j
- design thickness of the CFRP laminate at the beam–column joint region;
- Vo
- column shear demand based on full flexural over strength;
- Vc
- shear contribution of concrete;
- VN
- shear contribution of applied axial load “N”;
- Vs
- shear contribution by steel reinforcement;
- νfrp,j
- contribution of FRP to joint shear strength;
- Ø
- diameter of the rebar;
- Øinner
- inner bore diameter of the coupler sleeve;
- Øbolt
- diameter of the external bolt;
- ϕv
- shear capacity reduction factor;
- ϕf
- flexural capacity reduction factor;
- β
- angle of inclination between FRP wrap and column axis;
- θ
- angle between critical diagonal crack and column axis;
- ɛcu
- ultimate concrete strain based on the level of confinement by a composite jacket;
- ɛfrp
- ultimate unidirectional failure strain of the composite in tension;
- ɛyy
- strain in the longitudinal direction of the rebar due to tensile loading measured using DIC;
- ɛ1
- superficial principal strain in the lateral direction measured using DIC; and
- ξhyst
- equivalent viscous damping ratio/coefficient.
References
ACI (American Concrete Institute). 2019. Building code requirements for structural concrete and commentary. ACI 318-19. Farmington Hills, MI: ACI.
Ameli, M. J., D. N. Brown, J. E. Parks, and C. P. Pantelides. 2016. “Seismic column-to-footing connections using grouted splice sleeves.” ACI Struct. J. 113 (5): 1021. https://doi.org/10.14359/51688755.
Ameli, M. J., and C. P. Pantelides. 2017. “Seismic analysis of precast concrete bridge columns connected with grouted splice sleeve connectors.” J. Struct. Eng. 143 (2): 04016176. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001678.
Anagnostou, E., T. C. Rousakis, and A. I. Karabinis. 2019. “Seismic retrofitting of damaged RC columns with lap-spliced bars using FRP sheets.” Composites, Part B 166: 598–612. https://doi.org/10.1016/j.compositesb.2019.02.018.
Balsamo, A., A. Colombo, G. Manfredi, P. Negro, and A. Prota. 2005. “Seismic behavior of a full-scale RC frame repaired using CFRP laminates.” Eng. Struct. 27 (5): 769–780. https://doi.org/10.1016/j.engstruct.2005.01.002.
Capani, F., A. D’Ambrisi, M. De Stefano, F. Focacci, R. Luciano, R. Nudo, and R. Penna. 2017. “Experimental investigation on cyclic response of RC elements repaired by CFRP external reinforcing systems.” Composites, Part B 112: 290–299. https://doi.org/10.1016/j.compositesb.2016.12.053.
Chen, J. F., S. Q. Li, and L. A. Bisby. 2013. “Factors affecting the ultimate condition of FRP-wrapped concrete columns.” J. Compos. Constr. 17 (1): 67–78. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000314.
Chen, W., W. Shou, Z. Qiao, and S. Cui. 2019. “Seismic performance of non-ductile RC frames strengthened with CFRP.” Compos. Struct. 221: 110870. https://doi.org/10.1016/j.compstruct.2019.04.042.
Eslami, A., A. Dalalbashi, and H. R. Ronagh. 2013. “On the effect of plastic hinge relocation in RC buildings using CFRP.” Composites, Part B 52: 350–361. https://doi.org/10.1016/j.compositesb.2013.04.025.
FEMA (Federal Emergency Management Agency). 2000. Prestandard and commentary for the seismic rehabilitation of buildings. FEMA 356. Washington, DC: FEMA.
FEMA (Federal Emergency Management Agency). 2007. Interim testing protocols for determining the seismic performance characteristics of structural and non-structural components. FEMA 461. Washington, DC: FEMA.
Garcia, R., I. Hajirasouliha, and K. Pilakoutas. 2010. “Seismic behaviour of deficient RC frames strengthened with CFRP composites.” Eng. Struct. 32 (10): 3075–3085. https://doi.org/10.1016/j.engstruct.2010.05.026.
Haber, Z. B., K. R. Mackie, and H. M. Al-Jelawy. 2017. “Testing and analysis of precast columns with grouted sleeve connections and shifted plastic hinging.” J. Bridge Eng. 22 (10): 04017078. https://doi.org/10.1061/(ASCE)BE.1943-5592.0001105.
Han, W., Z. Zhao, J. Qian, Y. Cui, and S. Liu. 2018. “Seismic behavior of precast columns with large-spacing and high-strength longitudinal rebars spliced by epoxy mortar-filled threaded couplers.” Eng. Struct. 176: 349–360. https://doi.org/10.1016/j.engstruct.2018.09.007.
Huaco, G., and J. Jirsa. 2012. “Performance of damaged column retrofitted with innovative materials and devices.” In Proc., 15th World Conf. on Earthquake Engineering, 10. Red Hook, NY: Curran Associates.
IS (Indian Standard). 2000. Plain and reinforced concrete—Code of practice. 4th rev. IS 456. New Delhi, India: Bureau of Indian Standards.
IS (Indian Standard). 2008. High strength deformed steel bars and wires for concrete reinforcement—Specification. IS 1786. New Delhi, India: Bureau of Indian Standards.
IS (Indian Standard). 2009. Seismic evaluation, repair and strengthening of masonry buildings—Guidelines. IS 13935. New Delhi, India: Bureau of Indian Standards.
IS (Indian Standard). 2014. Reinforcement couplers for mechanical splices of bars in concrete—Specification. IS 16172. New Delhi, India: Bureau of Indian Standards.
IS (Indian Standard). 2016. Ductile design and detailing of reinforced concrete structures subjected to seismic forces—Code of practice. 1st rev. IS 13920. New Delhi, India: Bureau of Indian Standards.
Ingham, J. M., and A. S. H. Bai. 2009. “Seismic performance of mechanically coupled reinforcing bars.” Mag. Concr. Res. 61 (7): 529–537. https://doi.org/10.1680/macr.2008.00098.
Le-Trung, K., K. Lee, J. Lee, D. H. Lee, and S. Woo. 2010. “Experimental study of RC beam–column joints strengthened using CFRP composites.” Composites, Part B 41 (1): 76–85. https://doi.org/10.1016/j.compositesb.2009.06.005.
Park, Y. J., and A. H.-S. Ang. 1985. “Mechanistic seismic damage model for reinforced concrete.” J. Struct. Eng. 111 (4): 722–739. https://doi.org/10.1061/(ASCE)0733-9445(1985)111:4(722).
Parks, J. E., D. N. Brown, M. J. Ameli, and C. P. Pantelides. 2016. “Seismic repair of severely damaged precast reinforced concrete bridge columns connected with grouted splice sleeves.” ACI Struct. J. 113 (3): 615. https://doi.org/10.14359/51688756.
Phillippi, D. J., and G. A. Hegemier. 2013. “Use of mechanical couplers in concrete columns.” In AEI 2013: Building Solutions for Architectural Engineering, edited by C. J. Anumba and A. M. Memari, 715–724. Reston, VA: ASCE.
Rowell, S. P., and K. P. Hager. 2010. “Investigation of the dynamic performance of large reinforcement bar mechanical couplers.” In Structures Congress, edited by S. Senapathi, K. Casey, and M. Hoit, 2059–2075. Reston, VA: ASCE.
Seible, F., M. N. Priestley, G. A. Hegemier, and D. Innamorato. 1997. “Seismic retrofit of RC columns with continuous carbon fiber jackets.” J. Compos. Constr. 1 (2): 52–62. https://doi.org/10.1061/(ASCE)1090-0268(1997)1:2(52).
Shin, J., D. W. Scott, L. K. Stewart, C.-S. Yang, T. R. Wright, and R. DesRoches. 2016. “Dynamic response of a full-scale reinforced concrete building frame retrofitted with FRP column jackets.” Eng. Struct. 125: 244–253. https://doi.org/10.1016/j.engstruct.2016.07.016.
Shrestha, R., S. T. Smith, and B. Samali. 2009. “Strengthening RC beam–column connections with FRP strips.” Proc. Inst. Civ. Eng. Struct. Build. 162 (5): 323–334. https://doi.org/10.1680/stbu.2009.162.5.323.
Wang, D. Y., Z. Y. Wang, H. Li, and S. T. Smith. 2013. “Shaking table test of large scale nonductile RC frames retrofitted with FRP composites.” In Proc., 4th Asia-Pacific Conf. on FRP in Structures, edited by R. Al-Mahaidi, S. T. Smith, Y. Bai, and X.-L. Zhao. Melbourne, Australia: Swinburne Univ. of Technology.
Yang, Y., L. H. Sneed, A. Morgan, M. S. Saiidi, and A. Belarbi. 2015. “Repair of RC bridge columns with interlocking spirals and fractured longitudinal bars—An experimental study.” Constr. Build. Mater. 78: 405–420. https://doi.org/10.1016/j.conbuildmat.2015.01.010.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 26 • Issue 3 • June 2022
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Jun 30, 2021
Accepted: Jan 2, 2022
Published online: Feb 23, 2022
Published in print: Jun 1, 2022
Discussion open until: Jul 23, 2022
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.
Cited by
- Bu Wang, Xianhui Wu, Qi Liu, Yueyue Wu, Fei Huang, Linfeng Xu, Xing Wu, Yuanxin Deng, Effectiveness and Efficiency of Externally Bonded CFRP Sheets for Shear Strengthening of RC Beam-Column Joints, Polymers, 10.3390/polym14071347, 14, 7, (1347), (2022).