Study On Performance Of Anti-Progressive Collapse Based On The New Steel Joints

In recent years,vertical progressive collapse damage has occurred frequently,while the structure must have joints with sufficient bearing capacity,stiffness and ductility to resist progressive collapse damage.However,so far,there are few researches on steel joints which can improve the initial stiffness and bearing capacity without reducing the ductility.Therefore,in order to meet the anti-collapse requirements of steel joints for bearing capacity,stiffness and ductility,two new steel joints with stud reinforcement and steel plate reinforcement based on double web angle steel joints were proposed in this paper,through static pushover test and finite element analysis,the anti-progressive collapse performance based on the new steel joints substructure were studied.The main works are as follows:(1)Based on the double web angle steel joints,two new substructure test models of steel joints strengthened by stud and steel plate were designed and manufactured by using Q235 and Q345 steel.The static pushover tests of three substructure models were carried out by using the static pushover test method.The deformation and failure characteristics of the above substructure joints were studied,and the differences of their stiffness,bearing capacity and ductility were analyzed,especially the initial stiffness and the influence of initial stiffness and internal force in beam on the collapse resistance of substructure.The results show that the two new steel joints change the main failure characteristics of the substructure,and their initial stiffness and ultimate bearing capacity are significantly higher than those of the double web angle steel joints,and the ductility is almost unchanged,which indicates that the new joints effectively improved the anti-collapse performance of the substructure when the middle column fails.(2)The finite element calculation models of the above three substructure test models were established by ABAQUS finite element analysis software in refined analysis method.Through the finite element analysis,the stress and deformation properties of stud and connector of the new type of joint were studied;the stress distribution law of the bolt hole on the upper flange of the steel frame beam was analyzed;the bearing capacity,stiffness and ductility of the corresponding substructure were discussed and the bilinear joint moment-rotation mechanical analysis models were established.Compared with the experimental results,the results are in good agreement.(3)By ABAQUS finite element software,in which the constitutive model of hinge element is defined as the analysis model of joint moment-rotation proposed,the finite element analysis models of new steel joint plane steel frame and double web angle steel joint plane steel frame were established respectively in this paper.Using ABAQUS/Explicit module,the quasi-static analysis was carried out by applying linear increasing vertical displacement at the failure column,and the load displacement curves of two plane steel frame models were obtained,which are in good agreement with the experimental results.Then,the ABAQUS/Explicit module was used to remove the bottom middle column,inner column and side column of the frame,respectively,and the dynamic nonlinear finite element progressive collapse analysis of the above models were performed.According to the frame deformation,the end displacement of the column,and the time history curve of the corner of the beam-column joint,the anti-progressive collapse performance comprehensively were evaluated.The results show that the new steel joint frame has greater rigidity and bearing capacity than the double web angle steel joint frame.When the bottom middle column and inner column are removed,the failure displacement and beam end rotation angle of the new steel joint steel frame are smaller than that of the double web angle steel joint;when the bottom side column is removed,the failure time of the new steel joint steel frame is also greater than the failure time of the double web angle steel joint which indicating that it has better resistance to progressive collapse.