Local-Distorcional buckling interaction of thin-walled steel cold-formed lipped channel members in axial compression

Gustavo Yoshio Matsubara¹; Eduardo de Miranda Batista¹; Juarez Moara Santos Franco²

¹ COPPE - UFRJ; ² UFRRJ

doi:10.20906/CPS/CILAMCE2017-0331

Resumo

Thin-walled steel cold-formed lipped channel members in axial compression are susceptible to buckling phenomena in the following modes: Local buckling (L), Distortional buckling (D) and Global buckling (G), each of them related to its specific critical load, respectively PcrL, PcrD and PcrG. The lower critical load controls the predominant buckling mode. In addition, when the lowest critical loads are close enough (in some cases coincident) buckling modes interaction may develop. L-D is one of the most important buckling interaction, which occurs when Local and Distortional critical buckling loads are (nearly) coincident (PcrL= PcrD). However, virtually all design specifications and codes for cold-formed steel members do not handle properly the ultimate strength for the case of L-D interaction. The present article includes results of FEM numerical tests of cold-formed lipped channels subjected to axial compression in L-D buckling interaction (L-D). The FEM numerical analysis was performed with the help of the ANSYS computational program. Considering L-D interaction behavior requires a considerable amount of research work to improve the knowledge of the phenomenon, the research aims at contributing to the development of this area. To achieve this goal the investigation is based on: (i) literature review of experimental and numerical research on L-D interaction, (ii) elastic linear buckling analysis with the help of both finite element and finite strip methods, (iii) nonlinear FEM analysis of post buckling behavior affected by L-D interaction, (iv) calibration of the FEM model based on comparison between numerical and experimental results. The FEM-based nonlinear post buckling behavior takes into account pre-defined initial geometrical imperfections for prediction of ultimate loading, Pu. For this, initial geometrical imperfections were taken from the critical buckling mode, which may include L and D modes combination (PcrL≈ PcrD indicates buckling mode as a combination of L and D pure modes). Finally, the u

Palavras-chave: Steel Cold-Formed Member; Local-Distortional Buckling Interaction; Thin-Walled Structures; Finite Element Modeling; Buckling Analysis; Nonlinear Analysis