Cold-formed steel lipped and plain angle columns with fixed ends

A novel DSM-based approach for the rational design of fixed-ended and pin-ended short-to-intermediate thin-walled angle columns

“…10 It was found that the DSM local strength curve predicts reasonably well the numerical ultimate strengths of the shorter columns.…”

“…The post-buckling behaviour, strength and design of angle columns has attracted the attention of several researchers in the past (e.g., [1][2][3][4][5][6][7][8][9][10][11]). Nevertheless, numerical simulations recently carried out by the authors [12,13], concerning pin-ended (but with end-section warping prevented) and fixed-ended short-to-intermediate equal-leg angle columns, shed new light on key (and somewhat surprising) mechanical aspects related with the structural response of such members, namely the fact that it is strongly influenced by the interaction between two global buckling modes (one involving major-axis flexure and torsion, and the other minor-axis flexure only) 1 .…”

“…Although these DSM-based design approaches were shown (i) to provide efficient (accurate and reliable) estimates of the available pin-ended and fixed-ended experimental and numerical failure loads, and (ii) to outperform all their predecessors, they exhibit one nonnegligible drawback: the lack of an underlying rational structural model. This is mainly because they do not take into account explicitly the fact that the column behaviour and failure are governed by the interaction between minor-axis flexural and major-axis flexural-torsional (instead of local) buckling effects, which are markedly different for pin-ended and fixed-ended equal-leg columns [2][3][4][5][6][7][8][9][10][11][12][13].…”

Buckling Behavior of Cold-Formed Studs with Thermal Perforations

“…Ungermann [33,34] dealt with experimental and numerical investigations on plain channels subjected to coupled instabilities. Post-buckling behavior of cold-formed steel columns was observed by Schafer [35].…”

Short-to-intermediate slender pin-ended cold-formed steel equal-leg angle columns: Experimental investigation, numerical simulations and DSM design

“…Although the non-linear behaviour, strength and design of angle columns has attracted a lot of attention for decades (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14]), it was not until the last few years that the mechanics underlying the column non-linear behaviour were unveiled and properly understood [15,16] and it became clear why the current North American Specification (NAS) for Cold-Formed Steel Structures [17] still excludes short-to-intermediate equal-leg angle columns from (i) the pre-qualification for the Direct Strength Method (DSM) design and (ii) the application of the LFRD resistance factor / = 0.85, valid for all other cold-formed steel compression members. It was found that, although such columns buckle in flexural-torsional modes associated with a critical load plateau, the corresponding post-critical strength reserve changes considerably along that same plateau, thus affecting significantly the column failure load.…”