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Cold‐formed members – comparison between tests and a unified design method for beam‐columns
Author(s) -
Höglund Torsten
Publication year - 2015
Publication title -
steel construction
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.443
H-Index - 8
eISSN - 1867-0539
pISSN - 1867-0520
DOI - 10.1002/stco.201510002
Subject(s) - structural engineering , beam (structure) , buckling , centroid , eurocode , column (typography) , bending , cold formed steel , materials science , engineering , mathematics , geometry , connection (principal bundle)
In [1] a unified method for the design of steel beam‐columns is presented. The method has been checked for rolled steel beam‐columns and extruded aluminium beam‐columns. It is included in Eurocode 9 [19] for aluminium members and it is proposed to be included also in Eurocode 3 Part 1‐3 [16] as well, but then it needs to be checked for typical cold‐formed sections. Cold‐formed sections are usually un‐symmetric and thin‐walled, for instance channel sections or C‐shaped sections (lipped channels). When used as compression members, local buckling causes a redistribution of the longitudinal stress which leads to a shift of the effective centroid. The shift causes overall bending and reduces the column strength when the member is compressed between pinned ends. In fixed‐ended columns, however, the shift of the effective centroid is balanced by a shift of the applied force and bending is not introduced [6]. As a result, the strength of fixed‐ended channel column exceeds that of a pin‐ended column of the same effective length [7]. Using effective width for the flanges of channels e.g. according to EN 1993‐1‐5 [17] gives conservative result as the centroid of the effective section is too close to the web. The mixed effective width/effective thickness method for outstand elements given in Annex D of EN 1993‐1‐3 [16] is the basis in the following interpretations.