Research On The Distribution Of The Cold-formed Stresses And The Overall Stability Of The Axially Compression Members In The Effect Of Residual Stresses

Coldformed thinwa1 steel membersaredely aPPlieed in the engineering in thelast several decades.The eold-forllledsidual stresses are remained in the Coldfonnedthin-wall steel members when they are formed,d it eauses a great Influenee to theoverail stability as the members are subjeeted to the axle eenter Pressure force.Themanufacture Proeess of eoldformed thinwa1 steel members 15 very comPlex,d it,5 toodiffieult to Proeeed to analyze in theoretieally.50 there are few researeh achievemenisabout the coldformed residual stresses Whieh have many faults.And thatleads to the lackof the design fonnula of the overail stability involving the influence of the eold一fonnedresidual stresses. In this Paper, theoretieal brealhrough 15 exPlored firstly,the eoldfonned Proeess ofthe members 15 divided inio0 stages:the being formed(or member'5 loading) stage andthe elastie restoration(or member,5 unloading)stage.The Stresses in the member for eachstage are derived resPeetively:based on the theory of elastiePlastie the stresses for thebeing formed stage are obtained,then using the ANSYSfinite element analysis softwareimitates the elastie restoration stage as to obtain the ealeulating values of the stresses forthe elastie restoration stage.The sus,aehieved by adding the05ges stresses,arejustthe eoldbended residual stresses Whieh are more reasonable and more comPletc:besidesthe longitudinal residual stresses,the tangential residual Stresses and the radial residualssses are gained too;ineluding the residual stresses of bent segment,the residualstresses of straight segment are obtained too. Then,the initial stresses files whieh ean deseribe residual stfCsses areitten basedon the distribution of residual stresses obtained above.Exhaustively eonsidering all initialimPerfeetion sueh as eoldbended residual stresses,initial一bending and initial-eecentrieity,and using the finite element analysis software ANSYS to analyze the stability of axleeenter Pressure members of eold一formed thin·wall ehannel steel and henuning angle steel,therelationshiPs for these four kinds of sections are obtained.ComParing the eurvewith the Code,it ean be found thateurves of differeni kinds of seetions and sizesare very close;the stability coefficientsin thisper are equal to these in Code whenmembers'ratios to slcndemess are large:but when the ratios of slendeme:5 are small,eoeffieienisin this PaPer are a little lower than those in Code. Ai last,ealeulation formula of p 15 gained by fittingrelationshiPs obtainedab0Ve.