Fatigue Behavior of RC Beams Strengthened with GFRP Sheets

Abstract

The objective of the presented study is to examine the effects of glass fiber reinforced polymer (GFRP) composite rehabilitation systems on the fatigue performance of reinforced concrete beams. Experiments were conducted on beams with and without GFRP composite sheets on their tensile surfaces. The specimens were 152 ϫ 152 ϫ 1,321 mm reinforced concrete beams with enough transverse reinforcement to avoid shear failure. The results of this study indicate that the fatigue life of reinforced concrete beams with the given geometry, subjected to the same cycling load, can be significantly extended through the use of externally bonded GFRP composite sheets. An interesting finding is that, although the fiber strengthening system increases the fatigue life of the beams, the failure mechanism, fatigue of the steel reinforcement, remains the same in both strengthened and nonstrengthened beams. Thus, it is possible to predict the fatigue life of a cyclically loaded beam using existing fatigue models.

Bond durability of fatigued CFRP-steel double-lap joints pre-exposed to marine environment

“…Their high strength-to-weight ratios and weather resistance reignited interest in FRP composites for bridge repair and rehabilitation [9] during the late 1970s. In such applications, FRPs have demonstrated their ability to support the structural integrity of reinforced concrete (RC) [10][11][12][13][14][15]. With stiffness's similar to steel, carbon fibre reinforced polymers (CFRPs) have emerged to be one of the most appropriate composites for strengthening steel, e.g., CFRP have been demonstrated to increase the fatigue life and load carrying capacity of steel members [16][17][18].…”

Fatigue life prediction of RC beams strengthened with externally bonded FRP sheets

“…To validate the proposed model, an experimental database consisting of 28 prestressed/non-prestressed FRP sheets strengthened RC beams (Barnes et al 1999;Papakonstantinou et al 2001;Heffernan et al 2004;Quattlebaum et al 2005;Toutanji et al 2006;Yu et al 2011;Xie et al 2012) was established. All beams were reported to have failed with the rupture of tensile steel reinforcement.…”

Examination at a Material and Structural Level of the Fatigue Life of Beams Strengthened with Mineral or Epoxy Bonded FRPs: The State of the Art

“…Harries et al (2007) studied the effect of adhesive stiffness; the results showed that the generated stress in tensile steel under fatigue loading was greater with more flexible adhesive due to reduce ability of the adhesive to transfer stress to the strengthening material. From most of the studies Toutanji et al 2006;Barnes and Mays 1999;Shahawy and Beitelman 1999;Papakonstantinou et al 2001;Aidoo et al 2004;Masoud et al 2001;Dong et al 2011), the general behavior of beams strengthened with FRP is that there is an initial change in stiffness and increase of deflection due to a redistribution of the cracks in the beams. This is then followed by unchanging stiffness with increasing deflection due to the cyclic creep, the time evolution of the plastic strain under cyclic load, of the concrete as explained by Papakonstantinou et al (2001).…”

“…If the bonding of the FRP with the concrete substrate is defective, either because of sub-standard workmanship or design problems with the anchorage, any failure due to the debonding of the FRP will, for most cases, cause a steel rebar rupture; the fatigue life will obviously be impaired. Figure 8 shows the S-N data for sheet, laminate FRP strengthened beams and NSM strengthened beams from the literature (Barnes and Mays 1999;Breña et al 2005;Dong et al 2011;Heffernan and Eriki 2004;Papakonstantinou et al 2001;Yu et al 2011;Quattlebaum et al 2005;Badawi 2007 andAbdel Wahab 2011). This figure only includes data for rectangular beams to avoid any effects due to beam shape on the S-N model.…”

“…The fatigue failure mechanism of FRP composites is more complex than the failure of plain concrete or steel. Composite materials often show a much greater fatigue life than other homogenous materials (Papakonstantinou et al 2001), where cracks, due to fatigue, format a weak point and continue to grow with each load cycle. Conversely, if the individual fibers within FRP composites develop a defect, this defect does not propagate across the other fibers; thus, the undamaged fibers reduce the number of cracks that grow.…”