07.02: Distortional‐global interaction in lipped channel beams: Part I: Mechanics and elastic behaviour

Abstract

This work aims at presenting and discussing Generalised Beam Theory (GBT) numerical results concerning the elastic geometrically non-linear behaviour of simply supported lipped channel (LC) beams under uniform major-axis bending and experiencing distortional-global (D-G) interaction, making it possible to shed fresh light on the mechanics underlying this coupling phenomenon. Two LC beams geometries are considered, each exhibiting a different type of D-G interaction, namely (i) "true D-G interaction" (close global, McrG, and distortional, McrD, critical buckling moments), containing three critical-mode initial geometrical imperfection shapes (two global, due to the lack of symmetry, and one distortional) and (ii) "secondary global-bifurcation interaction -SGI" (McrD<<McrG), containing a critical-mode distortional initial imperfection. In order to clarify the surprising behaviour of the beam undergoing a SGI, an additional beam is analyzed, deemed to exhibit a "pure" distortional post-buckling behaviour. The GBT results provide the evolution, along given equilibrium paths, of the beam deformed configuration (expressed in modal terms), relevant displacement profiles and modal participation diagrams. The knowledge acquired has visible impact on the development of rational design rules for CFS beams affected by D-G interaction, a topic addressed in a companion paper.

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 ).…”