Estimation of Bond Strength and Effective Bond Length for the Double Strap Joint between Carbon Fiber Reinforced Polymer (CFRP) Plate and Corroded Steel Plate

Abstract

In this paper, we examine the development of the estimation models of bond strength and effective bond length for a double strap joint between carbon fiber reinforced polymer (CFRP) plate and corroded steel plate. The experimental study on the bond behavior between CFRP plate and corroded steel plate is summarized first and the analytical interfacial bond–slip model for CFRP plate externally bonded to corroded steel plate is proposed. Based on the theoretical stress analysis for the CFRP plate–corroded steel plate double-lap joint, the piecewise expressions of the interfacial shear stress and the normal peel stress of the interface between CFRP plate and corroded steel plate were established. The estimation models of the bond strength and the effective bond length for the double strap joint between the CFRP plate and the corroded steel plate were consequently developed on the basis of interfacial stress distribution equations and the stress boundary conditions. The comparison between the predicted and experimental results indicated that the proposed models could be adopted to predict the bond strength and effective bond length for the CFRP plates externally bonded to corroded steel substrates with reasonable accuracy. The proposed estimation models are expected to provide meaningful references and essential data for the reliable application of CFRP strengthening system to the performance improvement of corroded steel structures.

Stress Concentration Analysis of the Corroded Steel Plate Strengthened with Carbon Fiber Reinforced Polymer (CFRP) Plates

“…To interpret this phenomenon, the basis of the cooperative work of the corroded steel plate and CFRP plates is the load transfer of the adhesive layer, and the greater the thickness of the adhesive layer, the smaller the shear stiffness and the lower the load transfer efficiency of the interface between the corroded steel plate and the CFRP plates, and thus the worse the strengthening effectiveness. On the other hand, there is an effective bonding length on the bonding interface between the corroded steel plate and the CFRP plates [25,26]. Although the increase in adhesive thickness will lead to an increase in the effective bonding length of the CFRP plate, the strengthening effectiveness of the CFRP plates can still be fully exerted, since the bonding length of the CFRP plates in the models of this study is greater than the effective bonding length.…”

“…Recently, a few studies have been concerned with the applications of CFRP materials in the reinforcement of corroded steel structures. Chotickai [24], Li et al [25,26], and Xu et al [27] have investigated the bond properties between CFRP materials and precorroded steel plates. Sharaf et al [28] conducted an experimental and numerical analysis of the behavior of corroded steel plates strengthened with thin-ply glass/carbon hybrid FRP composites.…”

Fatigue Crack Propagation Prediction of Corroded Steel Plate Strengthened with Carbon Fiber Reinforced Polymer (CFRP) Plates

“…The line elastic constitutive model was adopted for the CFRP plate with an elastic modulus of 165 GPa and Poisson’s ratio of 0.3. The real constant of the spring element COMBIN39 (i.e., the F - D curves), which reflect the bond–slip relationship of the bonding interface between CFRP plate and corroded steel plate, was calculated according to the interfacial bond–slip model of CFRP plate externally bonded to corroded steel plate reported in the authors’ recent study [ 35 , 36 , 50 ]: where F was the force of the spring element COMBIN39, D was the displacement between the nodes at both ends of the spring element, τ and s were the interfacial shear stress and relative slip, respectively, and was the area covered by individual springs. The real constant (FSLIDE) of the bilinear force-deformation element COMBIN40 was calculated according to the maximum static friction force of the CFRP plate in the anchorage zone: where is the tensile force of the high-strength bolt in the anchor device (see Figure 1 , and more details can be found in [ 14 ]); is the static friction coefficient between CFRP plate and steel plate; is the compression area of CFRP plate in the anchorage zone.…”

“…The initial crack of the CFRP-strengthened defected steel plates in the existing numerical studies were generally simplified as a mode Ⅰ though crack, and the differences in the SIF values and crack propagation rate along the thickness direction of steel plate were always ignored. While the fatigue cracks of the corroded steel plate strengthened with CFRP materials initiated at the bottom of the rust pits on the steel surface, and gradually developed into partial-through surface crack and though crack with the increase in fatigue cycles [ 14 ], in addition, corrosion damage would also cause the change in the bonding performance of the interface between CFRP materials and steel substrate [ 35 , 36 ]. The corroded steel plate strengthened with CFRP is bound to have a distinctive mechanism and process of fatigue crack propagation with respect to the CFRP-strengthened cracked steel plates.…”

A review of FMLs performance test methods and index evaluation

“…It is worth noting that, compared with the short beam method, the double beam method has a pure shear stress point, which alleviates the influence of bending stress on the shear strength between layers to a certain extent [71,72]. At the same time, considering the application of double-beam shear method to resin-based composites, it has some specificity compared with the traditional interlayer shear performance test, and is gradually widely used in the shear performance test of FMLs [73][74][75].…”