STABILITY AND STRENGTH OF COLD-FORMED STEEL COLUMNS WITH INTERMEDIATE STIFFENERS

Resumo

Cold-formed steel (CFS) profiles have the advantage of combining low weight with high
strength capacity, which can be improved with the inclusion of intermediate stiffeners. This paper
analyzes the influence of stiffeners on CFS columns and proposes a search for geometry with highest
critical buckling load and highest compressive strength. For this purpose, (i) the lipped channel-type
parametric model was developed with flange and web stiffeners and (ii) performed the sensitivity
analysis that relates these variables to the mechanical performance of the columns. The elastic buckling
analysis was performed using the Finite Strip Method (FSM), which allowed identifying the local (L)
and distortional (D) buckling modes and the relationship between their critical loads (Rdl). The resistance
was obtained by nonlinear analysis with arc control technique, in an implementation of the Finite
Element Method (FEM). The parametric model also incorporated manufacturing constraints, such as
coil width, sheet thickness and usual bending angles. All studies adopt, as restriction, a constant area in
the cross section of the profile. This study is particularly interested in (i) verifying whether the signature
curves of the optimal profiles present common properties, such as the Rdl ≈ 1, and in cases where this is
verified (ii) measure resistance erosion due to LD interaction. The ultimate objective of this work is to
determine the value for Rdl that maximizes the strength of stiffened columns. Future applications of these
results include the development of resistance optimization routines based on FSM.