| With the continuous improvement of high-strength steel production and processing technology at home and abroad,high-strength steel has gradually been applied with its unique advantages.At present,the application of high strength steel in the field of domestic construction is still in its infancy,facing some problems to be solved,such as low ductility,high yield ratio,welding connection brittle fracture easily and so on.Especially,the welding of high strength steel is difficult and the welding sensitivity is high,different welding forms have a significant influence on the welding quality of high strength steel.At present,high strength steel is widely considered to have a broad application prospect in steel structure buildings.Because of the connection of steel frame flange welds in complex stress state,high strength steel flange by butt welds more prone to brittle cracking under earthquake.Therefore,it is necessary to carry out in-depth research on the fracture performance of high-strength steel beam-column welded joints against the structural form of butt weld,in order to provide reference for the application of high strength steel in construction engineering.This paper is based on 4 types of butt weld structure in the form of Q460 high strength steel beam-column flange butt weld welded joints,using finite element software ANSYS,simulating the existence of the welding process of welding residual stress,and through the distribution of fracture index along the critical path,compared and analyzed the fracture performance of the joints of 4 different butt weld structural forms.Designed four different types of butt-welded joints of high-strength steel beam column flange butt welded partial welded joints specimens,through the experimental study,comparison and analysis of the impact of butt weld structure and loading mode on the fracture properties of local welded joints of flanges of high strength steel beamcolumn,and the test and finite element numerical simulation results were compared,considering the influence of lining plate spacing on bilateral weld fracture properties of joints.The results are as follows:(1)By using the finite element software ANSYS,adopting the indirect couplingmethod of thermal structure,simulation of welding transient process of local welded joints of beam and column flanges in 4 different butt welded structures,calculate the welding residual stress distribution of the joint.(2)Based on the finite element model considering the welding residual stress,aiming at the critical path of cracking of welded joints,the fracture performance of joints is analyzed by comparing the fracture indexes.Comprehensive judgment,there is a high possibility that the welding joint will crack and destroy in the butt weld end and the central region of the beam flange,The lining is welded with double seam structure and the joint weld area is strengthened,and the fracture performance of the joint is better.At the same time,comparative analysis of the welding residual stress and no welding residual stress fracture performance of the node,The results show that the welded residual stress nodes are more likely to crack in the weld area.(3)Experimental results show that the different butt weld structures have great influence on the fracture performance of welded joints of high strength steel column flange,4 kinds of test specimens are mainly prone to cracking and cracking in the base material area and the fusion surface of the butt weld and the base material;The specimens with bilateral weld seam of the lining plate were damaged in the base material area and accompanied by a large amount of plastic deformation,which showed better fracture properties,mainly because the lining board adopts bilateral weld construction strengthen the strength of the weld zone,avoid fracture of weld and heat affected,so that the peak value of the specimen moved to the base metal area,destruction of the parent material plastic deformation,The fracture resistance of the specimen is strong.(4)The establishment of 4 kinds of butt weld structure refined finite element model of welded joint and compared with the test results.The results show that the fracture performance of the finite element calculation results better than the test results,mainly due to the finite element analysis without considering the initial defects and influence of crack;liner with bilateral weld structure test with the finite element calculation results are in good agreement,Mainly due to the finite element test piece cracking in the parent material is more likely to damage,accompanied by large plasticdeformation,which is basically consistent with the experimental results.(5)The finite element model is established to consider the influence of the distance between the two sides of the liner on the fracture performance of the joint,the results show that increasing the distance between the two sides of the lining increases the strength of the weld zone and shifts the peak stress outward,it is suggested that increasing width of the lining properly can reduce the possibility of cracking of the weld under the premise of the construction. |
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