| Concrete filled steel tubular(CFST)column offers the advantages of high strength,favorable ductility and convenient constructability,and has been widely used in civil engineering.Beam-column joints are the key parts of the structure,and reasonable beam-column joints will improve the mechanical properties of the structure.A new type of steel structure beam-column joint is proposed in this paper,namely the steel sleeve beam-column joint.Compared with the traditional beam-column joint,the joint is connected through interference fit,both on-site welding and bolting are avoided,which greatly improves the installation efficiency.A refined finite element analysis method is developed based on validation studies.The validation studies include comparison studies on the finite element analysis results of a similar beam-column joint with the experimental results and one on the finite element analysis results with the theoretical solutions.According to the hysteretic behavior of the joint under low-cycle reversed load,the reasonable structure is determined.Extensive parameters of the joint were explored to obtain the influences on the moment-rotation curves,according to the results of the parameter analysis,establish a moment-rotation curves calculation method.The specific research process is as follows:(1)The modeling method of steel sleeve beam-column joint in ABAQUS is described in detail.and verified by the existing similar tests and theoretical calculations.With orthogonal experimental design,nine beam-column joint finite element models are created,and the low-cycle reversed load is used in these models.(2)According to the hysteretic behavior of the joints,determine the reasonable dimension of the joints,such as the diaphragm width,sleeve thickness and sleeve height.(3)Based on the reasonable joint structure,the joints are analyzed from three aspects including material parameters,geometric parameters and load parameters,and the initial stiffness and bending moment-rotation curves of the joints under each parameter are obtained.(4)According to the results of parameterized analysis,the rigidity of the joint is discussed,and the calculation model of moment-rotation curves in the form of three-parameter power model is established.The following conclusions can be drawn based on the research work above: Through adjusting the dimension of the joint within the reasonable range,the plastic hinge can be set at beam end away from the sleeve,the high bearing capacity and the good energy dissipation capacity can also be reached.The main factors influencing the initial stiffness and bearing capacity of the joints were obtained by parametric analysis.According to EC3 specification,the steel structure beam-column joints were regarded as semi-rigid,but close to rigid with non-sway frames.A three-parameter power model was used to fit the simplified calculation method of the moment-rotation curves.The mathematical models were in good agreement with the finite element results. |
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