Article

Retrofitting of reinforced concrete beams using composite laminates

Construction and Building Materials (Impact Factor: 2.29). 01/2011; 25(2):591-597. DOI: 10.1016/j.conbuildmat.2010.06.082

ABSTRACT This paper presents the results of an experimental study to investigate the behaviour of structurally damaged full-scale reinforced concrete beams retrofitted with CFRP laminates in shear or in flexure. The main variables considered were the internal reinforcement ratio, position of retrofitting and the length of CFRP. The experimental results, generally, indicate that beams retrofitted in shear and flexure by using CFRP laminates are structurally efficient and are restored to stiffness and strength values nearly equal to or greater than those of the control beams. It was found that the efficiency of the strengthening technique by CFRP in flexure varied depending on the length. The main failure mode in the experimental work was plate debonding in retrofitted beams.

3 Bookmarks
 · 
323 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents test results at failure of 16 reinforced concrete (RC) continuous beams with different arrangements of internal steel bars and external carbon fibre reinforced polymer (CFRP) laminates. All test specimens had the same geometrical dimensions and were classified into three groups according to the amount of internal steel reinforcement. Each group included one unstrengthened control beam designed to fail in flexure. Different parameters including the length, thickness, position and form of the CFRP laminates were investigated. Three failure modes of beams with external CFRP laminates were observed, namely laminate rupture, laminate separation and peeling failure of the concrete cover attached to the laminate. The ductility of all strengthened beams was reduced compared with that of the respective unstrengthened control beam.Simplified methods for estimating the flexural load capacity and the interface shear stresses between the adhesive and concrete at failure of beams tested are presented. Comparisons between results from experiments and those obtained from the simplified methods show that most beams were close to achieving their full flexural capacity and the longitudinal elastic shear stresses at the adhesive/concrete interface calculated at beam failure conformed to the limiting value recommended in the Concrete Society Technical Report 55.
    Cement and Concrete Composites. 01/2004;
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper investigates the flexural behaviour of reinforced concrete beams strengthened using Carbon Fibre Reinforced Polymers (CFRP) sheets. The effect of reinforcing bar ratio ρ on the flexural strength of the strengthened beams is examined. Twelve concrete beam specimens with dimensions of 150 mm width, 200 mm height, and 2000 mm length were manufactured and tested. Beam sections with three different reinforcing ratios, ρ, were used as longitudinal tensile reinforcement in specimens. Nine specimens were strengthened in flexure by CFRP sheets. The other three specimens were considered as control specimens. The width, length and number of layers of CFRP sheets varied in different specimens. The flexural strength and stiffness of the strengthened beams increased compared to the control specimens. From the results of this study, it is concluded that the design guidelines of ACI 440.2R-02 and ISIS Canada overestimate the effect of CFRP sheets in increasing the flexural strength of beams with small ρ values compared to the maximum value, ρmax, specified in these two guidelines. With the increase in the ρ value in beams, the ratios of test load to the load calculated using ACI 440 and ISIS Canada increased. Therefore, the equations proposed by the two design guidelines are more appropriate for beams with large ρ values. In the strengthened specimens with the large reinforcing bar ratio, close to the maximum code value of ρmax, failure occurred with adequate ductility.
    Engineering Structures. 01/2007;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a joint experimental–analytical investigation aimed at studying the brittle failure modes of RC members strengthened in flexure by FRP plates. Both midspan and plate end failure modes are studied. The finite element analyses are based on nonlinear fracture mechanics. The model considered the actual crack pattern observed in the tests by using a smeared and an interface crack model. This paper shows how concrete cracking, adhesive behavior, plate length, width and stiffness affect the failure mechanisms. The numerical and experimental results show that debonding and concrete cover splitting failure modes occur always by crack propagation inside the concrete.
    Composites Part B: Engineering. 01/2007;

Full-text (4 Sources)

View
581 Downloads
Available from
May 21, 2014