Bond Behaviour Of CFRP Laminates Installed Onto Steel Plates With G Shaped Clamps

Abstract:Nowadays, the Carbon Fiber Reinforced Polymer (CFRP) has drawn much attention due to its high strength to weight ratio, excellent resistance to corrosion, easy to handle during construction and transport and so forth. Although most of the current researches focus on the strengthening of concrete structures, strengthening of steel structures with CFRP also attracted many researchers’interest. As shown by many researches, the most possible failure mode for steel structures strengthened with CFRP laminates is interfacial debonding. Since the mechanical properties of the CFRP laminates have not been fully performed under this mode, therefore a simple and efficient approach which can prevent or delay the debonding failure is needed. Comparing with existing clamps, G-shape clamp has obvious advantages which including the features of simple operation and strong clamping force etc. therefore, this thesis proposed to solve the debonding problem by using G-shape clamps. The main contents of this thesis are listed below:1. Considering the shear deformation of CFRP laminates and steel plates, the formula of interfacial stress was deduced. Based on the ultimate shear stress failure criteria and the existing models, the prediction formula of ultimate load of double lap joints was concluded as well.2. This thesis discussed the development of interfacial stress/strain, failure mode and mechanism of bond failure of CFRP/steel joints through the static tensile experiment of double lap or double sided specimens. By introducing parameter analysis, the effect of parameters such as bond length and anchored width of CFRP laminates on the bond behavior were studied.3. Through verifying the feasibility and effectiveness of the G-shape clamps in improving the bond behavior of CFRP/steel joints, together with applying a series of methodologies to install the clamps, this thesis preliminarily investigated the effect that clamp installation positions and anchored width have on improving the ultimate load. 4. By using ANSYS software, the bond behavior of CFRP laminates in strengthening steel plates was analyzed with finite element method. Considering the effect of different anchorage positions, the shear and peel stress-strain diagrams for different load were generated. A good agreement between the results from numerical analysis and experimental was achieved.