STABILITY AND RESISTANCE OF STRUCTURAL COLD-FORMED STEEL ELEMENTS WITH STIFFENED SECTIONS
João Pedro Magalhães Garcia1; Eduardo de Miranda Batista2; Juarez Moara Santos Franco3
1 Federal University of Rio de Janeiro; 2 COPPE / Federal University of Rio de Janeiro; 3 Federal Rural University of Rio de Janeiro
doi:10.20906/CPS/CILAMCE2017-0463
Resumo
This paper presents the results of a numerical-computational study on the flexural strength of stiffened trapezoidal steel members. Cold-formed open sections (CFS) are subjected to elastic buckling according to Local (L), Distortional (D) and Global (G) modes, which can be obtained by computational tools. Buckling analysis was based on Finite Strip Method (FSM) computational program CUFSM. The formulation for the prediction of the bending moment strength are related to (i) the critical bending moment associated to each of the modes L, D and G (respectively McrL, McrD and McrG) including possible interaction, (ii) combined with the cross-section initial yielding bending moment (My). In previous studies, aimed at establishing a sequence of procedures to specify typologies with the best ratio (Mcr vs. Cov) between critical bending moment (Mcr) and material utilization rate (Cov, which represents the cover rate provided by the roofing system), the authors concluded that the best performance solutions shows approximately the same critical bending moment results for L and D modes (McrL ≈ McrD). It is predicted in the literature, and confirmed by the experiments, that the interaction between buckling modes may cause degradation of the resistance, becoming more pronounced when the differences between critical moment values are sufficiently small (nearly equals) and the half-wavelengths of the modes (L and D in the present case) are multiples of each other. This leads to the conclusion that the best section geometry, according to the elastic buckling criteria, may not represent the best performance if structural strength is considered. In addition, for many cases, it was found that buckling modes of stiffened trapezoidal steel members does not fit the usual criteria foreseen in the literature. To clarify these two points (buckling mode identification and modal interaction in stiffened trapezoidal CFS in bending), the proposed paper is divided into two parts. The first part includes a parametric study of elastic buck
Palavras-chave: Cold-formed profiled sheeting; Stiffened cold-formed section; Buckling analysis; Bending moment strength