Interaction Of Global And Local Buckling In Thin-wall Welded Rectangular Hollow Section Compression Members

When the thin-wall welded rectangular hollow section (RHS) columns with axial compression reach their ultimate statement,it may be a global problem or a local buckling problem and or the interaction of the two problems.The interaction of global and local buckling is studied and it is the main focus of this thesis.It uses some experimental datas from the research project RFS-CR-10381 funded by the European Commission Research Fund for Coal and Steel and ANSYS (a kind of software for structural analysis) in the analysis of this thesis. Some work are also done to make clear what are the contents of "Code for Design of Steel Structures (GB 50017-2003)", "Technical Code of Cold-formed Thin-wall Steel Structures (GB50018-2002)" used in our country and the European code "EN1993-1" about the ultimate strength of the thin-wall welded RHS column with axial compression. And it is found that the interaction of global and local buckling is not or a litte considered in these different codes.The actual work made in this thesis are as follows:1. For each of the six RHS columns in the experiment,finite element models(FEM) by ANSYS software are made and are compared with the tests to calibrate the numerical model.When building the FEM models, the eigen buckling models chosen are models including the interaction of the global and local buckling.To consider global and local geometrical imperfections accurately, two FEM models of considering global geometrical imperfections fully and considering local geometrical imperfections fully are made for every column. 2. At the base of effective numerical model,it makes some research into the main factors influencing the ultimate strength of the thin-wall welded RHS members with axial compression. The factors are the global slenderness,the local slendness, global and local geometrical imperfections,the steel grade and so on.3. The results of the FEM numerical model are compared with "Code for Design of Steel Structures(GB50017-2003)", "Technical Code of Cold-formed Thin-wall Steel Structures (GB50018-2002)", Eurocode "EN 1993-1" and approaches recommended by some scholars. Some advice are also made to design the thin-wall welded RHS columns with axial compression in engineering practice after a lot of analyses.