Local buckling coefficient for cold-formed steel Sigma sections

Resumo

Cold formed steel profiles (CFS’s) allow the use of a variety of cross-sections, due to the flexibility of
manufacture and assembly. The use of CFS’s is generally associated with slender structural designs, with a large
ratio between the width and thickness of the members that compose its cross-section, which makes the profiles
lighter and more economical. CFS's are susceptible to instability due to the slenderness. This phenomenon induces
problems such as the local buckling of their members when subjected to compression. The design of these profiles
is approached by the Brazilian standard, and one of the calculation procedures presented is the Effective Section
Method (ESM), which considers local buckling through effective geometric properties of the cross-section. For
this purpose, the standard defines the buckling coefficient of the complete section by means of formulations for
specific profile types. In order to define a specific formulation for different cross-sections, it is necessary to
perform particular analyzes, such as numerical simulations using Finite Element Methods (FEM) or Finite Strip
Methods (FSM). Therefore, this work aims to define a formulation for the buckling coefficient of the complete
section of a Sigma profile, which is not defined in the scope of the Brazilian standard. For this, a numerical analysis
was developed using the ABAQUS finite element software. A parametric study was conducted through a range of
several Sigma profile's dimensions submitted to uniform compression. Based on the determinations of critical
buckling stresses from numerical analysis, a satisfactory formulation was developed. Furthermore, relevant data
about the study of local buckling behavior of Sigma-type has been determined and can be useful for their design.