Analysis For Distortional Buckling Of Cold-formed Thin-walled C-section Steel In Bending

In rencent years, the cold-formed steel has been more and more popular in building constructions. As an important strength-governing mode, distortional buckling is receiving more attentions. Based on the existing achievements on the distortional buckling of cold-formed thin-walled C-section steel in bending around the world, this dissertation summarizes some formulaes for half-wave length and elastic distortional buckling load and estimates their applicabilities by comparing with each other. This dissertation derivates and validates a new method for half-wave length and distortional buckling load of flexural members.Then, some detailed researches are made on the performances of cold-formed thin-walled C-section steel in bending througth finite-element analysis. The analyses include elastic analysis which aims at buckling mode, elastic buckling load and parametric study and elastic-plastic analysis intending to gain elastic-plastic buckling load and ultimate load capacity. It concludes that the finite-element model is both accurate and universal to analyse distortional buckling of flexural members. At last, this dissertation presents a measure to prevent distotional buckling and increase ultimate load capacity of cold-formed thin-walled C-section steel in bending by installing connecting bar between the lips of C-section steel at a determinate distance. By finite-element analysis, the validity of this strengthening method is validated and it is suggested that the more economic distance between connecting bars is the half of half-wave length.