Experimental And Model Investigation On Residual Stresses In Welded Medium-walled And Thick-walled I-shaped Sections Fabricated From Q460GJ

The diversified development of architecture including structural form and structural materials has led to the development of high strength and high performance structural steel,and our country has independently developed the GJ series structural steel which combine high strength and high performance.Because its yield strength of GJ series structural steel is not sensitive to the change of the thickness,GJ series structural steel are commonly used in medium-walled or thick-walled components.Up to now,GJ series structural steel has been used in some practical projects,but the research on the GJ series structural steel is lagging far behind.The medium-walled and thick-walled components have been used in the practical engineering without mature research,which will inevitably lead to the irrational use of high quality structural steel or unreasonable design.The residual stress has a great influence on the stability,fatigue strength and brittle fracture of the components,which is one of the key factors of the component analysis.At the same time,Q460 GJ has different stress-strain relationships and thermal properties from the mild structural steel.Both of stress-strain relationships and thermal properties have an effect on the formation of residual stresses,which means that the existing residual stress models for the mild structural steel may not useful to Q460 GJ.There is limited research on the residual stress distribution of medium-walled and thick-walled sections in Q460 GJ,which has seriously affected the promotion of high strength and high performance structural steel.Supported by the National Natural Science Foundation of China(NO.51578089),in this paper,the residual stress experimental study and the residual stress distribution model of welded medium-walled and thick-walled H-shaped sections fabricated from Q460 GJ structural steel are studied.The main contents of this paper are as follows:(1)The material test of Q460 GJ structural steel involved the thickness of 12 mm,25mm,42 mm was conducted,and the mechanical properties was obtained;(2)The sectioning method was adopted to obtain the residual stress of welded medium-walled and thick-walled H-shaped sections fabricated from Q460 GJ structural steel,meanwhile,the straightening measurement and curve correction was also used;(3)The slitting method was employed to investigated the change of the longitudinal residual stress alone the plate thickness;(4)Through the analysis of the experimental data,the effect of the variation of the width-to-thickness ratio,the thickness of the plate and the correlation of the web and flange on residual stresses are explored.(5)A simplified model of longitudinal residual stress distribution of welded medium-walled and thick-walled H-shaped sections fabricated from Q460 GJ structural steel is proposed,which will lay the foundation for the subsequent component analysis.(6)The influence of residual stress on the bearing capacity of compression columns are explored.Innovations in this paper:(1)For the first time,the thickness of the GJ series high strength and high performance structural steel was expanded to 42 mm to fill the blank of the residual stress on welded thick-walled H-shaped sections.(2)For the first time,through the analysis of the residual stress and distribution on welded medium-walled and thick-walled H-shaped sections fabricated from Q460 GJ,residual stress simplified model which is suitable for medium-walled and thick-walled Hshaped sections is put forward in order to analyze the bearing capacity of the components,which for the overall stability factor is of great significance.