Experimental and Numerical Investigation of Two Fixed-End RC Beams Strengthened With CFRP Bars in NSM Method

Document Type: Regular Paper


1 MSC, Structural Engineering, Roshde Danesh Institute of Education , Semnan, IRAN.

2 Associate Professor, Faculty of Civil Engineering, Semnan University, Semnan, IRAN.


Fiber-reinforced polymer (FRP) material is currently being produced in different configurations and widely applied to strengthening and retrofit concrete structures and bridges. It is also possible to apply other strengthening methods without changing the appearance or the dimensions of the structure. Near Surface Mounted (NSM) is a recent strengthening method using CFRP bars (rods or laminate strips) bonded into pre-cut grooves applied to the concrete cover of the elements to be strengthened. These FRP bars can help increase the flexural and shear capacity of existing concrete members as well. This article aims to present the experimental and numerical results gained separately from un-strengthened and strengthened beams under bending loading. In the experimental part, two large-scale fixed-end support reinforced concrete beams of the same size, and reinforcement characteristic was designed, constructed, and tested under one point concentrated loading system. The first specimen used as a control specimen while the second served as the strengthened applying NSM method with a new proposed hand-made CFRP Bar in the laboratory. Moreover; an extra analytical work was carried out using calibration of the analytical models as per the obtained experimental test results. The results and Photographs taken at the selected stages of loading are indicative of the fact that NSM method with FRP bars can be effectively applied to the existing structures in order to increase their flexural capacity, change their crack pattern and decrease final deflection.


Main Subjects

[1] Barros, JAO., Dias, S. (2003). “Shear strengthening of reinforced concrete beams with laminate strips of CFRP.” Cosenza (Italy), pp. 289–94.

[2] De Lorenzis, L., Teng, G. J. (2007) “Near Surface Mounted FRP Reinforcement: An Emerging Technique for Strengthening Structures.” Composites Part B: Engineering, No. 38, pp. 119-143.

[3] Asplund, S.O. “Strengthening Bridge Slabs with Grouted Reinforcement.”, ACI Structure Journal, Vol. 45, Issue 1, pp. 397-406.

[4] Nordin, H., Täljsten, B. (2006). “Concrete Beams Strengthened with Prestressed Near Surface Mounted CFRP.” journal of composites for construction, ASCE January.

[5] De Lorenzis, L., Nanni, A., La Tegola, A. (2000). “Flexural and shear strengthening of reinforced concrete structures with near surface mounted FRP rods.” In: Proceedings ACMBS III, Ottawa (Canada).

[6] Hassan, T., Rizkalla, S. (2002). ‘‘Flexural strengthening of prestressed bridge slabs with FRP systems.’’ PCI J., 47, 76–93.

[7] De Lorenzis, L., Nanni, A. (2002). “Bond between NSM fiber-reinforced polymer rods and concrete in structural strengthening.” ACI Structure Journal, 99(2):123–32.

[8] Carolin, A., Hordin, H., Taljsten, B. (2001) “Concrete Beams Strengthened with Near Surface Mounted Reinforcement of CFRP.” Proceeding of the International Conference on FRP Composite in Civil Engineering, CICE, Hong Kong, China, Dec 12-15, Vol. 2.

[9] Jalali,M., Sharbatdar, M. Kazem., Jian-Fei, Chen., Farshid Jandaghi Alaee. (2012). “Shear strengthening of RC beams using innovative manually made NSM FRP bars.” Construction and Building Materials, Volume 36, Pages 990-1000.

[10] Tanarslan, H.M. (2011). “The effects of NSM CFRP reinforcements for improving the shear capacity of RC beams.” Construction and Building Materials, Volume 25, Issue 5, Pages 2663-2673.

[11] Matteo, Breveglieri., Barros, JAO., Gláucia, M., Alessandra, Aprile. (2012). “A parametric study on the effectiveness of the NSM technique for the flexural strengthening of continuous RC slabs.” Composites Part B: Engineering, Volume 43, Issue 4, Pages 1970-1987.

[12] Mohammadian, M. (2010) “The Investigation of Flexural Behavior of RC Fixed-End Beams Strengthened with FRP Bars at NSM Method.” MS Thesis, Department of Civil Engineering, University of Takestan, Iran.