Research on the flexural buckling behavior of the cold-formed steel back-to-back built-up columns with Σ-section

Abstract

This paper presents a comprehensive study on the flexural buckling behavior of Cold-formed steel (CFS) back-to-back built-up columns with Σ-section (CFS-BBC-Σ), where compression tests and numerical simulations were conducted to investigate the influence of slenderness ratio and fastener arrangements. The material characterization, shearing resistance behavior of the fastener, and imperfection measurements were also performed. The test and simulation results revealed that reducing the fastener spacing and increasing the shearing-resistance stiffness could enhance the load-bearing capacity. The elastic global buckling load (Pcr) of CFS-BBC-Σ was determined using the energy method and verified against FEM simulations. The proposed energy method is an explicit expression that demonstrates high accuracy and ease of operation. Then, the Pcr was introduced into AISI-S100 specifications as an alternative to the modified slenderness ratio method (MSR) for calculating the load-bearing capacity (Pu) of CFS-BBC-Σ. Reliability analysis revealed that the proposed method provides more accurate and safe predictions for Pu than the original MSR in AISI-S100 specifications.