Hysteretic Behavior Analysis Based On Damage And Degradation Of Steel Frames With Ductile Nodes Under Cyclic Loading

Up to now, the joints research based on the theory of relocation of plastic hinge andthe research of steel frames in the plane have achieved some success, but theperformance of the new ductile nodes do not fully reflect the overall performance ofspatial steel frame. So based on the overall force of spatial steel frame and combiningwith research results of new ductile nodes, new Spatial steel frame models with ductilenode were established and simulated under the cyclic loading, seismic performancessuch as failure mechanism, hysteretic behavior, degraded performance, etc. and damageperformance at key positions were analyzed. All the results of these spatial steel framewith new ductile node steel may provide suggestions in designing and engineeringapplications.In accordance with domestic standards and U.S. design norms, the spatial steelframe with ordinary node(OSF), the spatial steel frame with symmetrical axillary platenode (SHF), the spatial steel frame with flange adapter plate node (FPF), the spatialsteel frame with arc-type expansion wing node (WFF), the spatial steel frame witharc-type weaken node (RBF) were designed. And then the teel frame models werecreated and analyzed under low cyclic loading by using ANSYS finite element analysissoftware.The development of stress and strain, the development process, hystereticbehavior of spatial steel frame were given, analysises of seismic performance anddamage degradation indicators wre comparaed. At last, advantages and disadvantages ofseismic performance ofthe various Spatial steel frame were listed.The results showed that: each steel frame with ductile node can achieve thepurpose of the relocation of plastic hinge, development of destruction were similar, forthe spatial steel frame with ordinary node(OSF), the spatial steel frame withsymmetrical axillary plate node (SHF), the spatial steel frame with flange adapter platenode (FPF), the maximum force in the column feet cause large plastic deformationoccur firstly, lower flange of the beam occur buckling outside the plane, in the end,because plastic deformation of the column foot and the beam end is too large, theoverall framework can not continue the development of deformation for redistribution of internal forces and damage. For the spatial steel frame with arc-type expansion wingnode (WFF), the spatial steel frame with arc-type weaken node (RBF)，large plasticdeformation appear at the end of beam spread wings and weaken the deepest firstly,followed by plastic deformation occurs in the column foot flange, which can delay thedevelopment of plastic hinges at the column foot. Finally structural damage due to largecolumn foot plastic deformation with Spatial steel frame torsion and capacityreduction.Plastic failure at the column foot will occur in all steel frame model, structuralmeasures must be taken to improve the flexural capacity of column foot by usingconcrete or stiffening ribs.Compared to the spatial steel frame with ordinary node, thespatial steel frame with ductile node have better performance in hysteretic behavior,ductility and energy dissipation capacity, have reduced stress and cracking index atbeam flange weld. loading capacity degradation varies in different steel frame models,stiffness degradation behaves more consistently.This research has some guiding values on engineering design and lay thefoundation for the further seismic performance study of Spatial steel frame with newductile nodes.