EFFECTIVE SECTION METHOD APPLICATION TO COLD-FORMED STEEL LIPPED ANGLE COLUMNS

Resumo

In the structural design of the cold formed sections, the procedures described in NBR
14762:2010 are adopted. The Brazilian standard establishes three bar design methods: Direct Strength
Method (DSM), Effective Section Method (ESM), and Effective Width Method (EWM). The DSM is
developed by calculating the geometric properties of the gross section. In the ESM, the local buckling
is considered through the effective section obtained directly, and not by the calculation of the effective
widths of its elements, as in the case of the traditional Effective Width Method (EWM). The
dispensation of numerical methods for elastic stability analysis constitutes a certain advantage of the
ESM in relation to the DSM. For cold formed steel section on compression, an important step is to
obtain the elastic buckling axial force, which in the case of ESM is obtained by means of an equation
that is a function of the local buckling coefficient for the complete section. The NBR 14762:2010
presents expressions of this coefficient for open sections of the type U, Z and rack, besides hollow
section. The objective of this work is to present a procedure to obtain the axial force of elastic
buckling, for lipped angles on compression, in order to complement the Effective Section Method. In
this context, an equation is present for the local buckling coefficient for lipped angle, as a function of
the geometric properties of the cross section.