Research On Performance Of Beam-column Inverted Channel Steel Joints In Steel Frame Under Central Column Failure

When the steel frame structure is in normal use,it may suffer from various accidental loads,such as vehicle impact,explosion and fire,which makes the structure collapse.The deformation and bearing capacity of beam column joints play an important role in the anti continuous collapse of the structure.The new type of reverse channel joint has the advantages of high construction efficiency,clear transmission path and less steel quantity.The upper and lower channel steel can transfer the load of the upper and lower flange of the beam respectively,and can release the residual stress and deformation.However,the mechanical properties of the joint under the failure of the middle column need further study.Therefore,the mechanical properties of the steel frame beam column reverse channel joint force under the failure of the medium column will be studied.Firstly,the finite element model of all sub structure is established.The validity of the model is verified by comparing the finite element simulation with the experiment.Secondly,the mechanical properties of iw2-3 and base nodes are compared and analyzed in detail.Finally,according to the end plate form,the reverse channel joints are divided into two groups A and B.the structure anti collapse performance of each group of models under different end plate thickness,channel web thickness and double vertical channel steel separation net distance is analyzed.The failure mode,beam end rotation capacity and deformation form,the stress process,the ratio and transformation process of bending mechanism and catenary mechanism are studied,The influence of the parameters of the studied nodes on the structure anti-continuous collapse is explained.The results show that the plastic hinge of the new type of reverse channel steel joint can protect the joint parts effectively away from the core area of the joint.The node has strong bearing capacity,deformation capacity and beam end rotation capacity,which mainly relies on the catenary mechanism to provide resistance.The thickness of web,end plate,net distance of double vertical channel and the stiffener set inside the channel have great influence on the development degree and rotation capacity of the joint resistance,while the external stiffeners of the channel have little influence on the mechanical properties of the joints.This paper puts forward reasonable suggestions for the size parameters of the reverse channel joints,which can provide reference for the subsequent research.