Study On Distortional Buckling And Strengthening Measures Of Cold-formed Thin-Walled Lipped Channel Columns

In recent years, the cold-formed steel has been more and more popular in building constructions. With the cold-formed steel members tending to higher strength, thinner and more complicate shape sections, distortional buckling, as an important strength-governing mode, has become an important research topic recently. It is very important for reseachers to study more on distortional buckling.In this study, firstly, three buckling modes of cold-formed lipped channels are emphasized, and the fundamental concepts and differences of the two methods mentioned above in Chinese and North American codes are compared, and the calculating process of the Direct Strength Method using the complete cross-section of the cold-formed steel members is illustrated. It indicates that the Direct Strength Method provides an entirely new and effective calculating method to design those cold-formed steel members with complex lipped channels, and their load-carrying capacity maybe governed by distortional buckling.Secondly, study on the behavior of distortional buckling through finite element analysis is carried out, and some finite element models are established using the software ABAQUS. Besides, some impact factors are investigated, and gained a lot of useful conclusions.Finally, one kind of strengthing measures is brought up, that is to say, to put several diaphragms along the channel can improve the buckling loads and the ultimate strength. And it is verified through finite element analysis.