Study On Procedure Of Crackle Extending Of Tradition Connection And Beam-Cover-Plate Reinforced Connection Of Steel Frame

The results that both at home and abroad of major earthquake damage investigation show a fact that the steel frame beam column connections are prone to brittle fracture under seismic load,which belongs to the weak link of the node design.At present,studies on cracking process of steel frame beam column and quantitative prediction of development of crack size are rarely reported in field of engineering.For the in-depth study of the fracture properties of steel frame beam column joints under earthquake,this paper introduced mature crack calculation method that is put forward by the domestic and foreign scholars,established the finite element model by using ANSYS software,to study the development of the crack that under the consideration of beam column ordinary nodes and beam-cover-plate reinforced joint,the main contents include:(1)Using ANSYS to establish common steel frame joint finite element model,then we can calculate the crack development process through the crack growth formulas.Compared with the existing test,the limit state occurred in thirtieth cycles through the finite element to simulate and it occurred in the thirty-first cycle through the test,There is only a cyclic load difference between them,so this method has a high reliability.(2)Discussing the influence of the joint area on the crack to the development of the butt weld joint through the change of the thickness of the transverse stiffening rib in the joint domain.(3)The results show that with the increase of stiffener thickness,crack develops faster;when 0.5 times more than the thickness of the stiffener beams,the crack length remained stable.(4)Defining the damage ratio according to the limit state of cracking.Considering the development of crack under cyclic loading with different initial crack size,judging the limit state by the damage ratio.Finally,listing a table.(5)Discussing the influence of the parameters of the cover plate on the crack length of the beam-cove-plate reinforced joint.The results show that with the increase of the length of the cover plate,the butt weld crack on the position of the maximum translate from the middle point to both ends,the crack length becomes larger,the fillet weld path of crack length change is not obvious;with the increase of the thickness of the cover,butt weld crack length decreases slightly;weld crack length decreases.The research results of this paper can provide some theoretical support for the analysis of fracture behavior of steel frame joints.