Title:
New Approach to Predict Shear Capacity of Reinforced Concrete Beams Strengthened with Near-Surface-Mounted Technique
Author(s):
Hadi Baghi and Joaquim A. O. Barros
Publication:
Structural Journal
Volume:
114
Issue:
1
Appears on pages(s):
137-148
Keywords:
beams; carbon fiber-reinforced polymers; near-surface-mounted technique; reinforced concrete; shear failure; shear strengthening
DOI:
10.14359/51689433
Date:
1/1/2017
Abstract:
Understanding the shear behavior of a concrete beam is still a challenging task due to several complex mechanisms involved. The Modified Compression Field Theory (MCFT) demonstrated an ability to predict, with good accuracy, the shear capacity of reinforced concrete (RC) members. Due to its iterative nature, the MCFT is not a straightforward design methodology, and a simplified MCFT (SMCFT) approach of this method was proposed to overcome this aspect. This model takes into account the tensile stress installed in the cracked concrete and inclination of the diagonal compressive strut, and requires a smaller number of model parameters than MCFT. This paper presents a new approach to predict the shear capacity of RC beams shear strengthened with fiber-reinforced polymer (FRP) laminates/rods applied according to the near-surface-mounted (NSM) technique. The new approach is based on the SMCFT and
considers the relevant features of the interaction between NSM FRP systems and surrounding concrete, such as debonding of FRP laminate/rod and fracture of surrounding concrete of FRP. The experimental results of 100 beams strengthened with different configurations and shear strengthening ratio of FRP reinforcements are used to appraise the predictive performance of the developed approach. By evaluating the ratio between the experimental results to the analytical predictions (Vexp./Vana.), an average value of 1.09 is obtained for the developed approach with a coefficient of variation of 11%.
Related References:
1. Bellamkonda, S. A., “Modeling of Shear Strengthening of Reinforced Concrete Beams Retrofitted with Externally Bonded Fiber Reinforced Polymers,” master’s thesis, Louisiana State University, Baton Rouge, LA, 2013, pp. 51-69.
2. Blanksvärd, T., “Strengthening of Concrete Structures by the Use of Mineral Based Composites,” Luleå University of Technology, Luleå, Sweden, 2009, pp. 141-184.
3. Vecchio, F. J., and Collins, M. P., “The Modified Compression Field Theory for Reinforced Concrete Elements Subjected to Shear,” ACI Journal Proceedings, V. 83, No. 2, Mar.-Apr. 1986, pp. 219-231.
4. Bentz, E. C.; Vecchio, F. J.; and Collins, M. P., “Simplified Modified Compression Field Theory for Calculating Shear Strength of Reinforced Concrete Elements,” ACI Structural Journal, V. 103, No. 4, July-Aug. 2006, pp. 614-624.
5. Dias, S. J. E., and Barros, J. A. O., “Shear Strengthening of RC T-Section Beams with Low-Strength Concrete Using NSM CFRP Laminates,” Cement and Concrete Composites, V. 33, No. 2, 2011, pp. 334-345. doi: 10.1016/j.cemconcomp.2010.10.002
6. De Lorenzis, L., and Nanni, A., “Shear Strengthening of Reinforced Concrete Beams with Near-Surface Mounted Fiber-Reinforced Polymer Rods,” ACI Structural Journal, V. 98, No. 1, Jan.-Feb. 2001, pp. 60-68.
7. Nanni, A.; Di Ludovico, M.; and Parretti, R., “Shear Strengthening of a PC Bridge Girder with NSM CFRP Rectangular Bars,” Advances in Structural Engineering, V. 7, No. 4, 2004, pp. 297-309. doi: 10.1260/1369433041653570
8. Bianco, V.; Monti, G.; and Barros, J. A. O., “Design Formula to Evaluate the NSM FRP Strips Shear Strength Contribution to a RC Beam,” Composites. Part B, Engineering, V. 56, 2014, pp. 960-971. doi: 10.1016/j.compositesb.2013.09.001
9. Park, S.-Y., “Prediction of Shear Strength of R/C Beams Using Modified Compression Field Theory and ACI Code,” KCI Concrete Journal, V. 11, No. 3, 1999, pp. 5-17.
10. Baghi, H., “The Effectivness of SHCC-FRP Panels of the Shear Resistance of RC Beams,” PhD thesis, University of Minho, Braga, Portugal, 2015, pp. 13-15.
11. Bianco, V.; Monti, G.; and Barros, J. A. O., “Theoretical Model and Computational Procedure to Evaluate the NSM FRP Strips Shear Strength Contribution to a RC Beam,” Journal of Structural Engineering, ASCE, V. 137, No. 11, 2011, pp. 1359-1372. doi: 10.1061/(ASCE)ST.1943-541X.0000370
12. ACI Committee 440, “Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-08),” American Concrete Institute, Farmington Hills, MI, 2008, 80 pp.
13. Dias, S. J. E., and Barros, J. A. O., “Performance of Reinforced Concrete T Beams Strengthened in Shear with NSM CFRP Laminates,” Engineering Structures, V. 32, No. 2, 2010, pp. 373-384. doi: 10.1016/j.engstruct.2009.10.001
14. Dias, S. J. E., and Barros, J. A. O., “Shear Strengthening of RC Beams with NSM CFRP Laminates: Experimental Research and Analytical Formulation,” Composite Structures, V. 99, 2013, pp. 477-490. doi: 10.1016/j.compstruct.2012.09.026
15. Dias, S. J. E., and Barros, J. A. O., “Shear Strengthening of T Cross Section Reinforced Concrete Beams by Near Surface Mounted Technique,” Journal of Composites for Construction, ASCE, V. 12, No. 3, 2008, pp. 300-311. doi: 10.1061/(ASCE)1090-0268(2008)12:3(300)
16. Dias, S. J. E., “Experimental and Analytical Research in the Shear Strengthening of Reinforced Concrete Beams Using the Near Surface Mounted Technique with CFRP Strips,” Department of Civil Engineering, University of Minho, Guimarães-Portugal, 2008. (in Portuguese)
17. Chaallal, O.; Mofidi, A.; Benmokrane, B.; and Neale, K., “Embedded Through-Section FRP Rod Method for Shear Strengthening of RC Beams: Performance and Comparison with Existing Techniques,” Journal of Composites for Construction, ASCE, V. 15, No. 3, 2011, pp. 374-383. doi: 10.1061/(ASCE)CC.1943-5614.0000174
18. Rizzo, A., and De Lorenzis, L., “Behaviour and Capacity of RC Beams Strengthened in Shear with NSM FRP Reinforcement,” Construction and Building Materials, V. 23, No. 4, 2009, pp. 1555-1567. doi: 10.1016/j.conbuildmat.2007.08.014
19. Islam, A. A., “Effective Methods of Using CFRP Bars in Shear Strengthening of Concrete Girders,” Engineering Structures, V. 31, No. 3, 2009, pp. 709-714. doi: 10.1016/j.engstruct.2008.11.016
20. Cisneros, D.; Arteaga, A.; De Diego, A.; Alzate, A.; and Perera, R., “Experimental Study on NSM Shear Retrofiting of RC Beams,” 6th International Conference on Composites in Civil Engineering (CICE 2012), Rome, Italy, 2012.
21. Moraes Neto, B.; Barros, J.; and Melo, G., “Model to Simulate the Contribution of Fiber Reinforcement for the Punching Resistance of RC Slabs,” Journal of Materials in Civil Engineering, ASCE, V. 26, No. 7, 2014, p. 04014020. doi: 10.1061/(ASCE)MT.1943-5533.0000913
22. Collins, M. P., “Evaluation of Shear Design Procedures for Concrete Structures,” Report prepared for the CSA technical committee on reinforced concrete design, 2001.