Bond–Slip Relationship for CFRP Sheets Externally Bonded to Concrete under Cyclic Loading

Abstract

The objective of this paper was to explore the bond–slip relationship between carbon fiber-reinforced polymer (CFRP) sheets and concrete under cyclic loading through experimental and analytical approaches. Modified beam tests were performed in order to gain insight into the bond–slip relationship under static and cyclic loading. The test variables are the CFRP-to-concrete width ratio, and the bond length of the CFRP sheets. An analysis of the test results in this paper and existing test results indicated that the slope of the ascending segment of the bond–slip curve decreased with an increase in the number of load cycles, but the slip corresponding to the maximum shear stress was almost invariable as the number of load cycles increased. In addition, the rate of reduction in the slope of the ascending range of the bond–slip curve during cyclic loading decreased as the concrete strength increased, and increased as the load level or CFRP-to-concrete width ratio enhanced. However, these were not affected by variations in bond length if the residual bond length was longer than the effective bond length. A bilinear bond–slip model for CFRP sheets that are externally bonded to concrete under cyclic loading, which considered the effects of the cyclic load level, concrete strength, and CFRP-to-concrete ratio, was developed based on the existing static bond–slip model. The accuracy of this proposed model was verified by a comparison between this proposed model and test results.

Experimental Study on Interfacial Bond Behavior between CFRP Sheets and Steel Plates under Fatigue Loading

“…These defective steel structures urgently need to be strengthened and repaired. During the last few decades, fiber reinforced polymer (FRP) composites, and especially for carbon fiber reinforced polymer (CFRP) composites, have gained more and more attention in the strengthening engineering of structures for its high strength-to-weight, stiffness-to-weight ratios and corrosion resistance [1,2,3,4,5,6,7,8,9,10]. In the meanwhile, as the most critical part, the bond behavior of the bonded interfaces between CFRP and steel directly determines the reinforcement effects of a steel structure reinforced by CFRP [11].…”

Design Optimization of Explosion-Resistant System Consisting of Steel Slab and CFRP Frame

“…In addition, there is also a demand for lightweight materials for lighter, faster and safer military vehicles. Recently, an efficient material substitute for steel has been carbon fiber-reinforced polymer (CFRP), which contains numerous unique characteristics such as high strength-to-weight ratio and high strength [ 2 ], high energy absorption capacity, and corrosion resistance [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Moreover, the tensile strength and stiffness of steel structure were improved significantly by CFRP [ 11 ].…”

Experimental Investigation of Fatigue Debonding Growth in FRP–Concrete Interface

“…Based on previous research, by using of externally bonded FRP plate, several premature debonding failures [12][13][14][15][16][17][18][19] may occur before the load reaching the expected failure modes, such as a rupture of the FRP plate or concrete crushing, and thus lead to unsatisfactory strengthening effects. The failure modes caused by FRP debonding can be broadly classified into two categories [20]: (a) plate end debonding: separation of the FRP plate or FRP plate attached with the whole thickness of the concrete cover from (or near) the plate end and then propagating towards the loading point; and (b) intermediate crack-induced debonding (IC debonding): debonding caused by the opening of the major flexural crack or flexural-shear crack and propagating towards the near plate end.…”