Study On Behavior Of Beam-to-column Minor Axis Connections Jointed By Double-angle In Steel Frame

Beam-to-column minor-aixs connections are as universal as strong- aixs connections in steel frame structure systerm,which is the important part in structure. At present, the research of beam-to-column minor-aixs connections are less , even most of which are on the rigid.So it is necessary to strengthen the study of the minor-axis semi-rigid connections. As a form of semi-rigid connections,double-angle connections are considered to be hinged and are assumed to transfer shear loads in design. However,it has been found that they have some rotational stiffness and can transfer some moments to the supporting members. So study on behavoir of minor-axis double-angle connections under cyclic load and putting forward design criteria are significant for theory and practice.Using the general finite element programming package of ANSYS10.0, this paper simulate the basic sample which is designed according to the actual situation and samples derived from different parameters synthetically considering nonlinear (material, geometry and contact) factors,and systematically analyzes hysteretic behavior,stiffness degradation and failure mechanism of beam-to-column minor-aixs connections jointed by double-angle under cyclic load.Otherwise this paper systemicly analyses the impact of major parameters to behavoir of the weak-axis double angle connections under cyclic load.the major parameters include slippage coeffcients,thickness of angles,dimension and grade of bolts and so on.It can be gained that this type of connections has good rotation capability and inter-story displacement angle can reach to 0.04rad. The breakage of samles mainly take place in the corner of angle. Stress of angle corner in vertical direction is large and plastic deformation is severe, ultimately a breach is formed.But its bearing capacity is small and it is can be gained the moment capacity reach to 0.16-0.2Mp from the samples'M/Mp-θcurve. The increasing of angle thicknenss,distance of back of angle limb and dimension of bolts can promote the bearing capacity and stiffness of connections.While its ductility may decline in some degree.The change of slippage coeffcients and axial compression of column has a little impact on behavior of connection,but the change can bring some impact on local stress state.According to the results of analysis, this paper argues that this type of connection should not be applied in the structure of strict control for inter-layer deformation displacement .The connection angle which is prone to damage in the design should be appropriate to strengthen to prevent components from being destroied prematurely.Node design should focus on The main factors,such as the thickness of angle steel, distance from the center line of bolts to the limb back of angle steel.The paper deeply analyses the behavior of beam-to-cloumn minor-axis connection jointed by double-angle under cyclic load and provide valuable information and reference for perfectting the system of connection theory, which can availably impulse steel frame system to be applied in more extensive field.