Strengthening of Reinforced Concrete Beams with Carbon Fiber-Reinforced Polymer Plates: An Experimental Study

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Yos Sompornjaroensuk
วิกร โตวราพงศ์
ปวริศ โปษยะนันทน์
ปฏิภาณ จันทรวิชิต
Damang Dy


This research paper deals with an experimental study of reinforced concrete beams in which the beams are strengthened in flexure by externally epoxy bonded carbon fiber-reinforced polymer (CFRP) plates. The objectives are to investigate flexural strength capacity and deflection response behavior of beams with two different types of reinforced beam cross section between single and double reinforcements. A total of 14 beam specimens with the same overall dimensions are cast-in-situ using ready mixed concrete for laboratory tests, which can be divided into two groups depending on steel reinforcement types. In each group of beams, the first four reinforced concrete beam specimens are imposed to be as the control beams that loaded by point loadings at the distance of one-third point of span length, and loaded at the distances of 1.5, 2.0, and 2.5 times of beam depth measured from two supports. The remaining three beam specimens are strengthened by CFRP plates and also loaded at 1.5, 2.0, and 2.5 times of beam depth measured from the supports in the same manner with control beams. The tested results have been prepared and given first for the load-deflection response. Analysis of obtained results are presented and discussed for cracking load, yielding load, debonding load, and ultimate load. Some results are compared with available theoretical calculated results.

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L.C. Hollaway and M.B. Leeming, Strengthening of Reinforced Concrete Structures: Using Externally-Bonded FRP Composites in Structural and Civil Engineering, Woodhead Publishing, Cambridge, 2001.

D.J. Oehlers and R. Seracino, Design of FRP and Steel Plated RC Structures: Retrofitting Beams and Slabs for Strength, Stiffness and Ductility, Elsevier Ltd., Oxford, 2004.

D.J. Oehlers and M.A. Bradford, Composite Steel and Concrete Structural Members: Fundamental Behaviour, Elsevier Science Ltd., Oxford, 1995.

A.H. Nilson and G. Winter, Design of Concrete Structures, 11th ed., McGraw-Hill Inc., Singapore, 1991.

R. Kotynia, FRP Composites for Flexural Strengthening of Concrete Structures: Theory, Testing, Design, Lodz University of Technology Press, Lodz, 2019.

ACI 440.2R-17, Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures, American Concrete Institute (ACI) Committee 440, Michigan, 2017.

O. Buyukozturk, O. Gunes, and E. Karaca, “Progress on understanding debonding problems in reinforced concrete and steel members strengthened using FRP composites,” Constr. Build. Mater., vol. 18, pp. 9-19, 2004

M.Z. Jumaat, M.H. Kabir, and M. Obaydullah, “A review of the repair of reinforced concrete beams,” J. Appl. Sci. Res., vol. 2, pp. 317-326, 2006.

L. Xiaoyong, Z. Zhigang, “Mechanical behavior of reinforced concrete beams externally strengthened with carbon fiber sheets,” Adv. Mat. Res., vols. 179-180, pp. 955-9, 2011.

N. Kim, Y.S. Shin, E. Choi, and H.S. Kim, “Relationships between interfacial shear stresses and moment capacities of RC beams strengthened with various types of FRP sheets,” Constr. Build. Mater., vol. 93, pp. 1170-1179, 2015.

W.N. Al-Rifaie, N.N. Ismaeel, and H. Riyad, “Rehabilitation of damaged reinforced concrete beams,” IOSR J. Mech. Civ. Eng., vol. 14, pp. 58-70, 2017.

B. Wan, C. Jiang, and Y.-F. Wu, “Effect of defects in externally bonded FRP reinforced concrete,” Constr. Build. Mater., vol. 172, pp. 63-76, 2018.

R.A. Hawileh, H.A. Musto, J.A. Abdalla, and M.Z. Naser, “Finite element modeling of reinforced concrete beams externally strengthened in flexure with side-bonded FRP laminates,” Compos. B Eng., vol. 173, article no. 106952, 2019.

D. Zhang, H. Shi, T. Ueda, and W. Jin, “Effect of U-shaped anchorages on concrete cover separation in carbon fiber-reinforced polymer-strengthened beams with notches at the sheet end,” Struct. Concr., vol. 22, pp. 50-68, 2020.

B. Zhou, R.-Y. Wu, and S. Yin, “Stress field approach for prediction of end concrete cover separation in RC beams strengthened with FRP reinforcement,” Polymers, vol. 14, article no. polym14050988, 2022.