Design of intumescent protection systems for concrete filled structural steel hollow (CFS) sections in the UK typically requires three input parameters: (1) a required fire resistance rating; (2) an ‘effective’ section factor; and (3) a limiting steel temperature for the hollow section. While the first of these is generally prescribed in building codes, the latter two require engineering judgement. This paper examines results from furnace tests on 21 CFS sections, 12 of which were protected with intumescent coatings by applying current UK design guidance. The protected sections demonstrate highly conservative fire protection under standard fire exposure; this is not typically observed for protected unfilled steel sections. Possible causes of the observed conservatism are discussed. It is demonstrated that the assumptions used in design guidance to calculate the effective section factor for protected CFS columns are physically unrealistic and inaccurate. Interim design guidance is given.
|Title of host publication||8th International Conference on Structures in Fire|
|Place of Publication||Shanghai|
|Publisher||Tongji University Press|
|Publication status||Published - 1 Jun 2014|