Study On The Reinforced Methods Of Joints By Enlarging The Column Section With Bonding CFRP Composite

In today, vigorously promote and develop the energy-saving society, people’s environmental awareness has been strengthened,energy-saving building have been support and development vigorously. Retrofitting on the existing old Building appropriately is that extending or improving its function with the economy technical means for the existing buildings Including old buildings to continuously adapt to the development of human society. It can effectively conserve resources and reduce environmental pollution caused by project garbage, and have important economic and social benefits and significance to alleviate the growing tension of urban land conflicts.The node as an important part of the connecting beams frame structure, not only bear the role of internal force transmission and distribution, but also to protect the integrity and stability of the building structure. It has a good and broad application prospects in practical engineering applications that by taking various measures to reinforce weak or damaged parts of note to improve its mechanical properties, so that the structure to meet the requirements and earthquake disaster prevention requirements.Since the reinforcement of existing conventional methods have advantages and disadvantages, in order to better used in engineering practice, this new technology uses reinforcement enlarge column section and the carbon fiber composite to achieve the reinforcement of reinforced concrete beam-column joints. Based on the available structural testing research and analysis results of reinforced concrete framework on domestic and foreign, the framework of the core area of the cross beams with stirrups little weak node as the research object, establish nonlinear finite element model of frame joints with existing nonlinear finite element analysis software ABAQUS. In three different axial compression ratio (0.3,0.45,0.6) for each group separately establish a contrast component and eight different plans reinforcement components, a total of 27 components. It was used to increase the column section reinforcement method, CFRP reinforcement method and a new column section increases with CFRP composite reinforcement method. Respectively by the methods of enlarging the column section reinforcement, bonding carbon fiber reinforced plastics and enlarging the column section with bonding carbon fiber reinforced plastics composite reinforcement method. Reinforcement method which increases the column section is divided into two programs whether to raise the stirrups in the core area of increasing column, CFRP reinforcement method is divided into two programs whether to paste CFRP in the core area, these two factors are also taken into account the variables on component design composite reinforcement method.Using static monotonic loading, applying constant axis pressure on top of the column, using hinged support at both ends of the column to limit its horizontal displacement, the vertical concentrated load antisymmetric is applied to both ends of the beam synchronously.The results showed that eight reinforcement programs except a single paste carbon fiber reinforcement programs have changed the nature of the components destruction, components becomes ductile failure by brittle failure, the ultimate bearing, stiffness and deformation capacity components both are improved. CoMPared to the single enlarge column section reinforcement and a single CFRP reinforcement, the ultimate bearing capacity of composite reinforcement scheme components improve significantly, even the programs with on stirrups and CFRP in the core area of the node also increased significantly, improved single CFRP reinforced components after reaching the ultimate load carrying capacity significantly decline. The stiffness of components which use several composite reinforcement program increased significantly and stiffness degradation are stable.For the displacement ductility factor components, the increase degree of composite reinforcement method is significantly higher than the sum of both two single reinforcement method.When the axial compression ratio is too large, on reinforcement components is carrying capacity decreased significantly, bonding carbon fibers significantly improved, and with axial compression ratio increases, bearing capacity of components have a slight increase, in the composite reinforcement, CFRP is required in the core area.