The Confinement of Concrete in Compression Using CFRP Composites – Effective Design Equations

Abstract

This paper presents the results of an experimental study on the behaviour of axially loaded short concrete columns, with different cross sections that have been externally strengthened with carbon fibre-reinforced polymer (CFRP) sheets. Six series, forming the total of 60 specimens, were subjected to axial compression. All the test specimens were loaded to failure in axial compression and investigated in both axial and transverse directions. According to the obtained test results, FRP-confined specimen failure occurs before the FRP reached the ultimate strain capacities. Thus, the failure occurs prematurely and the circumferential failure strain is lower than the ultimate strain obtained from the standard tensile testing of the FRP composite. In existing models for FRP-confined concrete, it is commonly assumed that the FRP ruptures when the hoop stress in the FRP jacket reaches its tensile strength from either flat coupon tests, which is herein referred to as the FRP material tensile strength. This phenomenon considerably affects the accuracy of the existing models for FRP-confined concrete. On the basis of the effective lateral confining pressure of the composite jacket and the effective circumferential FRP failure strain, new equations were proposed to predict the strength of FRP-confined concrete and corresponding strain for each of the cross section geometry used, circular and square. The estimations given by these equations were compared with the experimental ones and general conclusions were drawn.

Ductile Compressive Failure of Concrete Reinforced with High Strength Carbon Hybrid Composite

“…The progressively ductile failure of HC reinforced columns (without steel reinforcement) was distinctly different than those of conventionally CFRP-wrapped columns. Such columns with or without steel reinforcement were typically failed in a sudden and explosive manner by the complete rupture of the FRP jacket due to hoop tension [21,22].…”

Evaluation of calculation methods used for estimating the ultimate moment resistance of bridge decks reinforced with frp bars

“…Additionally to reinforcement bars, wires and ropes, FRP can be used in the form of strips, sheets and lamellas. FRP reinforcement can also be applied not only for reinforcing new concrete constructions as internal reinforcement, it can also be used in strengthening the structures as external reinforcement (Aktas, Sumer 2014;Barris et al 2012;Benzaid, Mesbah 2014;Daugevičius et al 2012;Fayyadh, Razak 2014;Lale Arefi et al 2014;Lapko, Urbanski 2015;Marčiukaitis et al 2007;Meisami et al 2013;Mostofinejad, Ilia 2014;Mostofinejad, Moghaddas 2014;Nelson, Fam 2014;Pakrastinsh et al 2006;Serdjuks et al 2003;Skuturna, Valivonis 2014a;Sprince et al 2013;Sundarraja, Prabhu 2013;Szolomicki et al 2015;Valivonis et al 2014). FRP reinforcement, as compared to steel, is lighter, resistant to corrosion, has a higher tensile strength, and is transparent to magnetic fields and electrically nonconductive.…”

Load-bearing capacity of flexural reinforced concrete members strengthened with fiber-reinforced polymer in fracture stage

“…According to EC2, the limit strain of the compressive concrete e cu could be taken as 3.5& when concrete strength f ck \ 50 MPa and e cu = 2:8 + 27((98 À f cm )= 100) 4 when f ck ! 50 MPa.…”

“…The use of fiber-reinforced polymer (FRP) materials for the strengthening of reinforced concrete (RC) structures became quite popular since its development in 1980s. [1][2][3][4] FRP materials are lighter and easier to install in comparison to the traditional strengthening materials such as concrete jackets, and steel plates. The use of FRP leads to the reduction of labor cost, although the cost fibers.…”