Loadbearing capacity of cold formed steel joists subjected to severe heating

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ConferenceInterflam 2001, 9th International Fire Science & Engineering Conference: 17 September 2001, Edinburgh, UK
Pages431442; # of pages: 12
Subjectcold formed steel, joist, fire resistance; Floors; Fire
AbstractThis paper discusses the behaviour of lightweight steel framed (LSF) unrestrained floors, protected with gypsum board ceilings, in five standard fire resistance tests. Parameters investigated in this test series were joist spacing, number of gypsum board layers in the ceiling membrane, floor cavity insulation and presence of concrete topping in the sub-floor. The fire resistance of LSF floors appears to be essentially governed by the ability of gypsum board to remain in place under fire exposure; other factors are of secondary importance.Retrospective numerical thermal-structural simulations of these tests show good agreement with measured temperature and deformation histories. The development of floor deflections is governed by the thermal bowing of steel joists except for the last one or two minutes in the tests, when ?run-away? deformations develop due to the formation of inelastic hinges near mid-span. Evaluation of bending moment resistance of heated joists using current design provisions for cold formed steel structures, adjusted to account for the deterioration of strength and stiffness of steel at elevated temperatures, leads to conservative and fairlyaccurate predictions of fire resistance.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number45009
NPARC number20378886
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Record identifier08f7a689-187f-45d2-85d1-85e9b62d1c75
Record created2012-07-24
Record modified2016-05-09
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