Análise da flambagem elástica de perfis de aço formados a frio com seções assimétricas na compressão axial e na flexão oblíqua

Abstract

The cold-formed steel members used in civil engineering construction are generally composed of symmetrical sections, usually classified as thin-walled members, which has led to the development of specific technical standards for structural design. Unconventional sections, such as asymmetrical shapes, although not explored in research and applications is the main goal of the present work. For this, asymmetrical sections derived from channel and Z-section, simple and stiffened, were studied in both axial compression and oblique flexural bending. The developed investigation is addressed to buckling analysis, with the support of reliable numerical-computational tools, allowing the identification of the concerned buckling modes. For the Global mode, analytical solutions were developed and, presented for axial compression, resulting in a practical method of direct resolution of the critical load in asymmetrical sections. For the oblique flexural bending, a direct equation was developed allowing finding the global buckling critical bending moment for open sections, considering general bending around any centroidal axis. For the Local mode, the buckling coefficients were obtained, considering the asymmetrical sections analyzed, and even, Z-section in the condition of oblique flexural bending. The obtained results may be taken into consideration, as complementary design tools regarding the current provisions of Brazilian Standard NBR 14762:2010. The present research also highlighted inconsistencies to be observed in the Brazilian standard, and therefore, suggestions for improvement of this document.