The Research On Mechanical Behavior Of The Light Steel Portal Frame Bean-column Joints

Light steel structure with its low cost, construction speed, has been widely applied. However, the corresponding design specification does not perfecting, and mostly used for common steel, especially in node positions, method of nodes calculating is not very satisfactory. Therefore, the research on character of gabled frames light-steel structure connections have an important the meaning of theoretical study and value of engineering applications.In this paper, considering the material nonlinearity, geometric nonlinearity and the status of non-linear, the study of gabled frames beam-column end-plate connections is made by the general finite element programming package of ANSYS10.0. Finite element simulation results show that almost all the beam-column connection specimen at loads showed good ductility. End-plate thickness on the carrying capacity of the connection has a clear impact. With the end-plate thickness increases, the connection the initial stiffness and bearing capacity increase. But, when the end-plate was increased to 20mm this role has become very weak. Bolt diameter has a little effect on the joint. Increasing bolt diameter, ductility and plastic rotation will reduce. But when the bolt diameter increased to 20mm seismic performance is very weak. The form of end-plate has a great effect on capacity of joint. Erect end-plate connection has higher carrying capacity and limits of joint stiffness than horizontal end-plate.But horizontal end-plate connection has a better seismic performance .Friction coefficients have little effect on the joint. Increasing friction coefficients, ductility and plastic rotation will reduce.Based on the above simulation analysis, we propose modified connection (IN1,IN2 and IN3).The improved structure is better than the common structure in load capacity. It is simple and feasible for construction. It relieves the stress concentration of node area, which can imp- rove the ductility performance and load capacity of node area.According to the results of finite element method, improved bolt calculation model , instability theory of plate and check the formula were proposed.To sum up, in this paper, the mechanical behavior of the light steel portal frame beam-column joints were roundly and deeply analysised. On this basis, modified connection were proposed, improved bolt calculation model , instability theory of plate and check the formula were proposed. It is valuable to direct practical engineering design and theoretical study.