Experimental Study on CFRP-to-Steel Bonded Interfaces under Quasi-Static Cyclic Loading

Fatigue behavior of FRP-to-steel bonded interface: An experimental study with a damage plasticity model

“…Similar to Zhou et al [56] observations, Doroudi et al [34] experimental bond-slip behavior of CFRP-to-steel bonded interfaces under quasi-static cyclic loading showed damaged plasticity behavior, indicating the necessity for a damaged-plasticity-type model to define the bond-slip behavior under quasi-static cyclic loading. However, considering the differences between the fracture surfaces in CFRP-to-steel bonded interface and those of CFRP-to-concrete bonded interface, and that the interfacial fracture energy strongly depends on the fracture surface, the constitutive models developed for CFRP-to-concrete bonded interfaces cannot be directly applied to a CFRP-to-steel bonded interface.…”

“…This damage parameter is typically calculated assuming a damaged elasticity, i.e., when unloading after the onset of damage, the interfacial shear slip is unloaded to zero at zero interfacial shear stress [36,38]. However, a recent study by the authors [34] showed that the damaged elasticity assumption is not valid for the bond-slip behavior of a CFRP-to-steel bonded interface made using Sikadur 30 adhesive. The experimental results presented in Doroudi et al [34] clearly showed a plastic slip during the unloading once the damage started to occur.…”

“…However, a recent study by the authors [34] showed that the damaged elasticity assumption is not valid for the bond-slip behavior of a CFRP-to-steel bonded interface made using Sikadur 30 adhesive. The experimental results presented in Doroudi et al [34] clearly showed a plastic slip during the unloading once the damage started to occur. It was also shown that the stiffness values of the unloading/reloading curves of the bond-slip relation tend to reduce with an increase in the interfacial slip.…”

“…In total, six single-shear pull-off test specimens were fabricated and tested. The set-up used in the current tests was similar to that used by Doroudi et al [34], and included a thick steel plate (thickness = 17 mm, length = 250 mm) supported on a rigid support block, and a pultruded CFRP plate bonded to the top surface of the thick steel plate and loaded at one end (Fig. 1).…”

“…While extensive research has been carried out on understanding the behavior of the CFRP-to-steel bonded interface under quasi-static monotonic loading [30][31][32][33], much less has been done on understanding the behavior of such bonded interfaces under cyclic loading. There are only a few studies so far that focused on understanding the behavior of CFRP-to-steel bonded interface under cyclic loading [34]. Therefore, there is a need for studies that provide a better understanding on the fatigue behavior of CFRP-to-steel bonded interface subjected to cyclic loadings.…”