Study On Behavior Of CFRP Strengthen Concrete-Filled Steel Tube Under Eccentric Tension

It is proved that utilising carbon fiber reinforced polymer (CFRP) composite material in strengthening reinforced concrete specimens can be effective and economical, which has been studied largely by many scholars all over the world. However, there are few studies on behavior of CFRP strengthen CFST under eccentric tension. Since it is common that CFST is subject to eccentric tension in practical projects, it is necessary to study this kind of behavior. In this paper, the combination of experimental and theoretical studies was used to investigate the performance of CFRP Strengthen CFST under eccentric tension.The main research works were summarized as follows:(1) In order to demonstrate the necessity and feasibility of the research in this paper, the relevant research status at home and abroad were systemically summarized firstly.(2) Including 13 CFST with bonded CFRP and 6 CFST without CFRP strengthening,19 experimental specimens subject to axial and eccentric tension were carried out in this paper. The test parameters contain number of CFRP layers, CFRP strengthening method and load eccentricity ratio. The research results indicate CFST can improve its bearing capacity obviously if strengthened by CFRP.(3) New material models of FRP were put forward which are suitable to be implemented in the finite element (FE) software ABAQUS. Numerical modeling was conducted based on the material models. The existing test data were used to verify the accuracy and reliability in the FE model.(4) Based on this FE model, the mechanism was deeply analyzed, including the state of stress and strain of CFRP, concrete and steel and the contact pressure between them. Meanwhile, a large number of parameters analyses were performed on the influences of strength of concrete, strength of steel, thickness of CFRP, steel ratio and load eccentricity ratio on axial and eccentric bearing capacity of CFRP strengthen CFST.(5) Based on the conclusions from the analysis of mechanism and parameters, the practical formulae of bearing capacity of the CFRP strengthen CFST under axial and eccentric tension were proposed. The predicted results of the practical formulae were in good agreement with those of tests. The study may provide reference to practical construction.