Research On Hysteretic Performance Of Polyline Weakened Joints

In the Northrich and Hanshin earthquakes,buildings collapsed as a whole due to joint failure.Since then,RBS nodes began to receive attention.However,it has been proved through research that RBS node's out-of-plane instability was caused by the reduction of beam and column node's out-of-plane stiffness due to the weakening of beam flange section.Wilkinson proposed a wedge-shaped weakening member to solve the problem that RBS nodes are prone to out-of-plane instability.Based on this weakening method,a kind of broken line weakening member is proposed in this paper,which can improve the bearing capacity of the joint and reduce the stress concentration in the depth of the wedge weakening node.In this paper,the polyline weakening joint not only adopts the design method that the weakening joint can realize the outward plastic hinge,but also avoids the out-of-plane instability of the joint caused by the weakening beam section.In order to study the effectiveness of finite element simulation,a weakened joint was simulated and compared with its experiment,which proved the effectiveness of ABAQUS simulation.After that,the author compares the three types of weakened joints with the traditional ones in failure state,bearing capacity,ductility coefficient,stiffness degradation and critical stress path,and obtains the advantages of the broken line weakened joints.In this paper,by changing the node web also weaken the part center distance pillar(a),beam web plate weakened part of the starting point of the maximum depth and web weaken the deepest position and post parameters(b),the distance of the study of these parameters under the node failure form(c),the position of plastic hinge,hysteresis properties,skeleton curves,strength and stiffness degradation performance,energy dissipation capacity,etc.Through research,it is proved that the polyline weakening node can form plastic hinge in the weakening part,realize the outward movement of plastic hinge,increase the ductility of the node,and give the reasonable range of the weakening size of polyline weakening node,which provides some theoretical basis for the seismic performance of polyline weakening node.The space steel frame structure was finally established by using ABAQUS finite element method.The stress cloud diagram,hysteretic performance and load-carrying capacity of thespace steel frame with a polyline weakening type are analyzed by comparing the space steel frame with the traditional steel frame with a reasonable weakening size.