Research Of Welded Defects On Directed Welded Tubular Jionts And Of The Influence On The Ultimate Strength Of Directed Welded Tubular Jionts

With the emergence and abroad use of new welded structure forms, there are some accidents in the welded structure due to the people's ignorance of the characteristics of the new welded structure forms and of the exist of the welded defects in welded structures. For the new welded structure forms of space tubular steel frame possessing directed welded joints, it is necessary for rational check and accept and safely use of the welded structure to realize types and characteristics of welded defects easily existing in directed welded lines and to know the degreed of influence to the ultimate strength of the welded joints.The background of this article is the space tubular frame room-project of HeLong palaestra. Author of this article choose eight directed welded K-jionts, strictly construct welding line by welded norm, get the welded defects into welded joints by different entities that simulate representative welded defects on the welded line or in the welded line such as pore, dregs, welded hump, borderline gap and gaps, calculate and analyze eight directed welded joints without welded defects and more than six hundred directed welded joints with welded defects by ANSYS program, and get influential curves to ultimate strength of directed welded joints with different welded lines or same welded lines on different location. From the curves, wo can know there is no influence when the defects is small, the directed welded joints with large displacement fe more sensitive than small, there are more uses to gaps than pore, dregs, and welded hump, and there is deep decline on the ultimate strength of the welded joints when the width welded hump is equal to the width welded line.This article consider that: there is on decline by strictly constructing welding line by welded norm; there are limitation to different welded defects; it is too stricted to welded norm now and it is necessary to map out and perfect the norm of check and accept special to steel structure; it is necessary to study the new methods and new equipments of checking welding line...