07.03: Distortional‐global interaction in lipped channel beams: Part II: Strength, relevance and DSM design

Abstract

This work aims at presenting and discussing numerical results concerning the post‐buckling behaviour, strength and design of two types of simply supported lipped channel (LC) beams under uniform major‐axis bending and undergoing distortional‐global (D‐G) interaction. The relevance of the interaction effects is assessed by determining the beams whose ultimate strength and/or failure mode are visibly affected by them. Distinct (i) global‐to‐distortional critical buckling moment ratios (RGD) and (ii) yield‐to‐non critical buckling (distortional or global) moment ratios (Ry) are considered and, thus, different failure mode natures (global, distortional or interactive) are expected. For each beam type, combinations of 41 geometries and 11 yield stresses are dealt with, in order to (i) characterise the beams experiencing “true D‐G interaction” (RGD≈1.0) and “secondary global‐bifurcation D‐G interaction” (RGD >1.0 + high Ry) and (ii) investigate the possible occurrence of “secondary distortional‐bifurcation D‐G interaction” (RGD <1.0 + high Ry). The results presented consist of (i) relevant non‐linear equilibrium paths, (ii) deformed configuration evolutions along those paths and (iii) figures providing the failure mode characterisation. Then, the numerical failure moments obtained are compared with their predictions by (i) the currently codified DSM (Direct Strength Method) beam global and distortional strength curves, and (ii) proposed DSM‐based design approaches, specifically developed to handle D‐G interactive failures.

Distortional-Global Buckling Interaction Relevance in Cold-Formed Steel Lipped Channel Columns

“…Yang and Hancock (2004), Dinis et al (2007), Camotim et al (2009), Kwon et al (2009), Silvestre et al (2012), Martins et al (2018c), ), (ii) distortional-global, DG (e.g. Dinis and Camotim (2008), Rossi et al (2010), , Niu et al (2014a), Niu et al (2014b), Anbarasu and Murugapandian (2016), Martins et al (2016), Martins et al (2017a), Martins et al (2017b), Martins et al (2018b), Martins et al (2018d)) and (iii) local-distortional-global, LDG (e.g. , Santos (2014), Santos et al (2014a), Santos et al (2014b), Cava et al (2016), Young et al (2018), Dinis et al (2018) and ).…”