Techno Press
Techno Press

Steel and Composite Structures   Volume 28, Number 2, July25 2018, pages 233-250
DOI: http://dx.doi.org/10.12989/scs.2018.28.2.233
 
Nonlinear behavior of axially loaded back-to-back built-up cold-formed steel un-lipped channel sections
Krishanu Roy, Tina Chui Huon Ting, Hieng Ho Lau and James B.P. Lim

 
Abstract     [Full Text]
    Back-to-back built-up cold-formed steel un-lipped channel sections are used in cold-formed steel structures; such as trusses, wall frames and portal frames. In such built-up columns, intermediate fasteners resist the buckling of individual channelsections. No experimental tests or finite element analyses have been reported in the literature for back-to-back built-up coldformed steel un-lipped channel sections and specially investigated the effect of screw spacing on axial strength of such columns. The issue is addressed in this paper. The results of 95 finite element analyses are presented covering stub to slender columns. The finite element model is validated against the experimental tests recently conducted by authors for back-to-back built-up cold-formed steel lipped channel sections. The verified finite element model is then used for the purposes of a parametric study to investigate the effect of screw spacing on axial strength of back-to-back built-up cold-formed steel un-lipped channel sections. Results are compared against the built-up lipped channel sections and it is shown that the axial strength of un-lipped built-up sections are 31% lesser on average than the built-up lipped channel sections. It was also found that the American Iron and Steel Institute (AISI) and the Australian and New Zealand Standards were over-conservative by around 15% for built-up columns failed through overall buckling, however AISI and AS/NZS were un-conservative by around 8% for built-up columns mainly failed by local buckling.
 
Key Words
    cold-formed steel; built-up sections; un-lipped channels; screw spacing; back-to-back sections; axial strength; finite element analysis
 
Address
(1) Krishanu Roy, James B.P. Lim:
Department of Civil and Environmental Engineering, The University of Auckland, Auckland, New Zealand;
(2) Tina Chui Huon Ting, Hieng Ho Lau:
Faculty of Engineering and Science, Curtin University Malaysia, Miri, Sarawak, Malaysia.
 

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