Analysis On Mechanical Behavior Of Double-limbs Built-up Cold-formed Steel Box Member

Cold-formed steel C section flexural members of heart and heart do not coincide,the torsional shear ability,in order to improve the stability and bearing capacity,this paper proposes a split double limb cold-formed thin-walled steel members,through the two C steel plate is arranged in the middle of filling,split into a box section surface form.In order to study the mechanical properties of double limb built-up cold-formed steel beams,using ANSYS finite element software to split bending and axial compression performance issimulated and analyzed,discussed in plate failure mode,ultimate bearing on the building element and displacement ductility influence,study shows:1.Assembly members in bending stress condition: Split member failure performance for mixed mode distortion section between the flexural buckling and local buckling and fill plate,did not show the overall distortional buckling or torsional buckling.(1)Fill plate width on split the flexural performance of a greater impact,when the fill plate width in the range of220mm~340mm,with the fill plate width increases,the ultimate bending component bearing capacity and flexural stiffness increases,the ductility decreases with increasing filler plate width.(2)Fill plate spacing to split the flexural bearing performance impact is larger,when the fill plate spacing in the 240mm~400mm range,with the fill plate spacing decreases,the ultimate bending component bearing capacity and flexural stiffness increases,displacement ductility decreases with the increasing of fill plate spacing.(3)Influence of flange width to thickness ratio of the building element is obvious,when the components of flange width to thickness ratio changes in the range of 35~48,with the flange slenderness ratio increases,the flexural ultimate bearing capacity is smaller,the changing tendency of flat flange width tothickness ratio the greater the damage degree of the flange is bigger,failure mode the distortion of local mixed failure becomes distorted and damaged,the damage on the flange plate gradually increased,the ductility decreases with the increase of the ratio of flange width to thickness.2.The building element pressure stress state on the shaft: Split member failure performance for mixed mode distortion section between the flexural buckling and local buckling and fill plate;At the same time,local buckling occurred in the first web,did not show the overall distortional buckling or torsional buckling.(1)Influence the fill plate width on the compression performance of the building element,when the fill plate width in the range of210mm~330mm,with the fill plate width increases,the ultimate bearing capacity of axial compression and axial stiffness increases,the ductility increases with the increase of filler plate width.(2)Effects of fill plate spacing on the building element is larger,when the fill plate spacing in the 197mm~356mm range,with the decrease of fill plate spacing,axial compression bearing capacity and axial stiffness increases;at the same time change fill plate spacing,only the damage degree of the component,does not change the component failure the final model,are web flange damage,with some damage.The displacement ductility increases with the decrease of the fill space.(3)Influence of flange width to thickness ratio of the building element is obvious,when the ratio of flange width to thickness changes in the range of 35~48,with the flange slenderness ratio increases,increases the bearing capacity of axial compression limit,flange width thickness ratio is larger,component failure degree of flange is also larger,but does not change the failure model components,displacement ductility increases with the increase of the ratio of flange width to thickness.