Istrazivanja i projektovanja za privreduJournal of Applied Engineering Science


DOI: 10.5937/jaes0-39645 
This is an open access article distributed under the CC BY 4.0
Creative Commons License

Volume 21 article 1117 pages: 758-766

Suhaib Sabah Abdulhameed*
Civil Engineering Department, Mustansiriyah University, Baghdad, Iraq

Dina Mukheef Hamza
Civil Engineering Department, Mustansiriyah University, Baghdad, Iraq

This paper investigated the behavior of reinforced concrete (RC) beams of near surface mounted (NSM) strengthening technique with using steel bar and hybrid steel bar. The effects of NSM reinforcement and load patterns on the flexural behavior and ductility of the RC beams have been studied. A four-point bending test was carried out on five reinforced concrete beams divided into two groups. The first group was tested under the effect of static load, whereas the second group was tested under repeated load. The experimental results are reported regarding the failure mode, flexural strength, load-deflection response, cracking behavior, and ductility. These results showed that strengthening of concrete beams with NSM steel bar increased the yielding and ultimate loads by about 28.6% and 28.5% respectively as compared to control beam, whereas the yielding and ultimate load increased to 33% and 35.7% over the control beam when strengthened with hybrid NSM steel bar. The ductility index of the control beam was equal to 2.6, this value increased to about 24.6% and 52.3% of the NSM steel bar and NSM hybrid steel bar strengthened beams respectively. The repeated load decreased the load capacity of the strengthened hybrid beams by about 65%, whereas the mid-span deflection is nearly the same.

View article

The authors would like to thank the Mustansiriyah University (, Baghdad - Iraq, for its support in the present work.

1.      Danraka, M.N., Mahmod, H.M., Oluwatosin, O.K.J. and Student, P., 2017. Strengthening of reinforced concrete beams using FRP technique: a review. International Journal of Engineering Science, 7(6), p.13199.

2.      Barris, C., Sala, P., Gómez, J. and Torres, L., 2020. Flexural behaviour of FRP reinforced concrete beams strengthened with NSM CFRP strips. Composite Structures, 241, p.112059.

3.      Szabó, Z. K., and Balázs, G. L., 2007. Near surface mounted FRP reinforcement for strengthening of concrete structures. Periodica Polytechnica Civil Engineering, 51(1), pp. 33-38. DOI:10.3311/

4.      Soliman, S.M., El-Salakawy, E. and Benmokrane, B., 2010. Flexural behavior of concrete beams strengthened with near surface mounted fiber reinforced polymer bars. Canadian Journal of Civil Engineering, 37(10), pp.1371-1382. DOI:10.1139/L10-077

5.      Askar, M.K., Hassan, A.F. and Al-Kamaki, Y.S., 2022. Flexural and Shear Strengthening of Reinforced Concrete Beams Using FRP Composites: A State of The Art. Case Studies in Construction Materials, p.e 01189.

6.      Nurbaiah, M.N., Hanizah, A.H. and Farhana, I., 2014. Flexural Behavior of Reinforced Concrete (RC) Beams with Externally Bonded (EB) Carbon Fiber Reinforced Polymer (CFRP) Sheets. In InCIEC 2013 (pp. 637-648). Springer, Singapore. DOI:10.1007/978-981-4585-02-6_55

7.      Thamrin, R. and Zakiyyah, A., 2021, April. Effect of reinforcement ratio on flexural behavior of reinforced concrete beams strengthened with CFRP plates. In IOP Conference Series: Earth and Environmental Science (Vol. 708, No. 1, p. 012015). IOP Publishing. DOI:10.1088/1755-1315/708/1/012015

8.      Wu, Z.S., Sakamoto, K., Niu, H.D., Shimada, M. and Murakami, S., 2002, June. Strengthening effects of concrete flexural members retrofitted with hybrid FRP composites. In Proc. of the third international conference on composites in infrastructure (ICCI'04), CD-ROM, California, USA.

9.      El-Hacha, R. and Rizkalla, S.H., 2004. Near-surface-mounted fiber-reinforced polymer reinforcements for flexural strengthening of concrete structures. Structural Journal, 101(5), pp.717-726.

10.   Grace, N.F., Abdel-Sayed, G. and Ragheb, W.F., 2002. Strengthening of concrete beams using innovative ductile fiber-reinforced polymer fabric. Structural Journal, 99(5), pp.692-700. DOI:10.14359/12309

11.   Abdalla, J.A., Mohammed, A. and Hawileh, R.A., 2020. Flexural strengthening of reinforced concrete beams with externally bonded hybrid systems. Procedia Structural Integrity, 28, pp. 2312-2319.

12.   Abdalla, J.A., Hawileh, R.A., Nawaz, W. and Mohammed, A., 2018, February. Reinforced concrete beams externally strengthened in flexure using hybrid systems. In 2018 Advances in Science and Engineering Technology International Conferences (ASET) (pp. 1-5). IEEE. DOI:10.1109/ICASET.2018.8376864

13.   Choobbor, S.S., Hawileh, R.A., Abu-Obeidah, A. and Abdalla, J.A., 2019. Performance of hybrid carbon and basalt FRP sheets in strengthening concrete beams in flexure.  Composite Structures, 227, p.111337.

14.   Hawileh, R.A., Rasheed, H.A., Abdalla, J.A. and Al-Tamimi, A.K., 2014. Behavior of reinforced concrete beams strengthened with externally bonded hybrid fiber reinforced polymer systems. Materials & Design, 53, pp.972-982.

15.   ASTM A370,”Mechanical Testing of Steel Products,” ASTM International, West Conshohocken, PA, (2021).

16.   ASTM C39,”Compressive Strength of Cylindrical Concrete Specimens,” ASTM International, West Conshohocken, PA, (2021).

17.   Sika group. (2020). SikaWrap230C. /dms/us01/g/sikawrap_hex-230c.pdf

18.   Sika group. (2022). Sikadur®-300. /dms/gcc/7/sikadur_-300.pdf

19.   ACI Committee, 2008. Building code requirements for structural concrete (ACI 318-08) and commentary. American Concrete Institute.