Seismic Failure Mechanism And Design Countermeasures Of Cantilever Beam Splicing Of Box Strengthen-joint Region Connection For Weak Axis Of I-section Column

After the Northridge earthquake in 1994 and Kobe earthquake in Japan in 1995,the seismic performance of beam-to-column connection joints welded on site was suspected,and the beam-column connection with cantilever beam section was paid more attention.The connection of the beam-column connection with the cantilever beam section has the characteristics of “actory welding,field splicing”.This connection overcomes the shortcomings of on-site welding to climate,high welding technician requirements and difficult to control welding quality,has the advantages of good energy dissipation capacity and fast construction.Based on the former on the node domain of box type strengthened I-shaped column weak axis connections(new weak axis connections model)of the research results,this paper designs two model with cantilever beam splicing weak axis connections specimens,one for the standard specimen(S-2),another for short cantilever beam section material specimens(S-5),by test and finite element analysis software ABAQUS to carry on the thorough analysis of two specimens.The experimental results show that the ductility coefficient,energy dissipation coefficient and stiffness degradation coefficient of the two specimens do not show obvious regularity.The maximum ductility coefficient of the specimen is 2.44,which indicates that the ductility coefficient of the new weak-jointed joint with cantilever beam segment is to be improved.The stress of nodal domain of the two specimens is still in the elastic stage at the maximum load moment,in line with the "strong node domain" of the force characteristics.The stress of the joints is large and dangerous,which is very unfavorable to the seismic resistance of steel frame joints.So,it is necessary to guarantee the location of the weld quality in the actual project.The results of finite element analysis show that the S-2 and S-5 are less than 15% of the yield loads and the peak load errors,which means that the finite element simulation can well fit the stress of the specimen under cyclic loading.The ductility coefficient of the finite element simulation is larger than that of the test but still less than 3.The thickness of the skin plate has a great influence on the damage form of the node.The use of higher strength steel can delay the time of the cantilever beam splicing joint into the yielding stage and improve the ultimate bearing capacity of the steel frame.Using duty cantilever beam end nodes can improve the bearing capacity of the node,but its ductility decreases.When the cantilever beam segment using bolt-welded hybrid connection,this paper recommended the cantilever beam length is 1-2 times as high beam but should not be more than 1.6 meters.