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

Flexural strengthening of steel beams using carbon fiber reinforced polymer (CFRP) laminates has gained popularity within the structural engineering community due to the many advantages it offers over traditional strengthening methods. Such advantages include ease of construction, resistance to corrosion, and minimal disruption to traffic. The interfacial shear stress transfer mechanism of the CFRP-to-steel bonded interface is critical to the performance of flexurally strengthened steel beams using externally bonded CFRP laminates. Many existing studies have investigated the behavior of CFRP-to-steel bonded joints under quasi-static monotonic loading; however, few studies have been carried out on understanding the behavior of such bonded joints under cyclic loading. This paper presents an experimental investigation aimed at understanding the behavior of CFRP-to-steel bonded joints under quasi-static cyclic loading. The experimental study presented consists of nine single shear pull-off tests of FRP-to-steel bonded joints, covering three different bond thicknesses and both quasi-static monotonic and quasi-static cyclic loading. The results are discussed in terms of their failure mode, load-displacement behavior, CFRP plate axial strain distribution, interfacial shear stress distribution, and bond-slip behavior.