The Research On The Whole Stability Of Axially Loaded Compression Members Of Cold-formed Thin-walled Steel Sections In The Effect Of Residual Stress

It is a universal phenomenon that residual stress exists in steel structures The existence of residual stress makes certain parts of member develop plasticity ahead, thereby reduces the whole stability of member. It is an important factor that influences the whole carrying capacity of member In technical code of cold-formed thin-wall steel structures GB50018-2002,the calculation of stability carrying capacity of axially loaded compression members does not consider the influence of the residual stress. By using of the large finite element software ANSYS, the whole stability of axially loaded compression members of cold-formed thin-walled steel sections in the effect of residual stress is studied in the paper.In the paper, the results of experience and rules of distribution of the cold-formed residual stress are analyzed, the models of the cold-formed residual stress that are close to the fact are founded, initial stress files of ANSYS which can describe the magnitude and distribution of the residual stress are established. Through leading the files into the stability analysis of ANSYS, ultimate load in the effect of residual stress can be gained. The method can be applicable to simulate difficult distribution of the residual stress.According to the feature that residual stress does not change with pole, the program is compiled to deal with the difficulties in writing file when there are a great of elements.The main study object of the paper is channel steel whose finite element models are founded in ANSYS The material is assumed as elastic-plastic body. The stability carrying capacities of members in the effect of diversified factor are calculated and compared. Through stability calculations of the model that are of cold-formed residual stress and l/1000 initial out-of-straightness, (?) - λ curve that reflects the fact can be gained. Comparing the curve with the code and results of experience, it is proved that the curve is reasonable and the stability coefficient @ of the code should be suitable to improve.