Stability Behavior Of Perforated Channel Column With Web Holes And Complex Edge Stiffeners Under Eccentric Compression Around Weak Axis

As for the manufacturing technology of cold-formed thin-walled steel members,the research on the most important stability issues of cold-formed thin-walled steel members has been continuously carried out.However,with the continuous emergence of new sections,the emergence of opening methods for web holes,and the development of high-strength steels,many new stability problems have been brought to cold-formed thin-walled steel members.At present,domestic and foreign researches on cold-formed thin-walled steel axial compression members with web openings have become mature,but the research on bias members is still scarce,and the research objects are mostly U-shaped or C-shaped grooves with one bead Steel members.However,the research of web-opening bias members with complex sections is even rarer.At the same time,in previous studies at home and abroad,most of the research on new types of openings was limited to different crimping forms or just different stiffening methods.Few combinations of openings,complex crimping and stiffening cross sections were used.Research.In addition,the DSM method for the axial compression members with web openings has been well studied,but the research on the biasing members with web openings is still rare.China’s code has not yet provided a clear calculation method for such components.In view of the above problems,this article has carried out experimental research on the bearing performance of 16 complex crimped channel steel opening members under eccentric loads around the weak axis.8 crimped channel steels each.Investigate its bearing characteristics such as ultimate bearing capacity and instability mode.The test results show that the stiffening of the web can increase the critical buckling load of the component under certain circumstances,effectively control the occurrence of local buckling of the web,and significantly increase the ultimate bearing capacity of the negative eccentric compression member.Affected by the phenomenon of effective centroid shift,the actual centroid of the unstiffened member is shifted to the curling direction,so the ultimate bearing capacity of the unstiffened member at a similar positive load eccentricity is slightly larger than that of the stiffened section member.The finite element method is used to simulate the test,and the comparison with the test proves that the model can better simulate such specimens.At the same time,three different plate thicknesses were selected,and a total of 139 web-opening and non-opening members of the two cross-section types selected in Chapter 2 were analyzed by finite element analysis under different load eccentricities.The results show that the opening of the web will have a significant impact on the load-bearing efficiency of the component.As the plate becomes thicker,the holes weaken the load-bearing efficiency of the C-shaped section member,and it also has a certain effect on the offset of the effective centroid.The weakening effect of the opening of the hole on the load-bearing efficiency of the Σ-shaped member decreases with the thickness of the plate.As the plate becomes thicker,the eccentricity at which the ultimate bearing capacity of the C-shaped section member reaches the highest point gradually decreases.The effect of web stiffening on the bearing capacity of the component is also very significant.When the plate is thinner,the webstiffening has a greater effect on improving the load carrying efficiency of the component,but as the plate becomes thicker,the web stiffening improves the load carrying efficiency of the component It will become smaller and even weaken the bearing capacity of the component.As the eccentricity of the load increases,the influence of web stiffening on the bearing capacity of the component decreases.Based on the existing research on biased components in China and the direct strength method provided by the relevant North American codes,the simulated components were verified and a direct strength method formula considering the effective centroid offset was proposed to prevent the occurrence of effective centroid offset.The moving C-shaped cross-section member was verified by calculation.The formula proposed in this paper is suitable for calculating the ultimate bearing capacity of two kinds of complex crimped channel steel asymmetrical axis biased members with and without holes.