AS3600-2009 fire rating for columns
AS3600-2009 fire rating for columns
(OP)
Hey everybody,
I refer you to table 5.6.4 note 1: "The first order eccentricity"... blah blah... "e/b has been taken as <=0.025 with emax = 100mm". I take it this clause limits the table usage to columns with tiny moments and high axial loads.
For example I'm designing a 600 by 300 column which is 4000mm high. I'm taking the effective length as 4m because only the 300mm wide face is attached to the slab, thus I can't use table 5.6.3 as it is limited to columns with an eff. length less then 3m. My fire actions are 380kN and 195kNm respectively which give an e=513mm! Which means that I can't use table 5.6.4 either cause e must be less then 100mm. Apart from using the Eurocode 2, referenced in clause 5.3.1, how else do I get a fire-rating for this column?
I think this eccentricity limit is a little over the top and should be reviewed, anyone else care to comment?
I refer you to table 5.6.4 note 1: "The first order eccentricity"... blah blah... "e/b has been taken as <=0.025 with emax = 100mm". I take it this clause limits the table usage to columns with tiny moments and high axial loads.
For example I'm designing a 600 by 300 column which is 4000mm high. I'm taking the effective length as 4m because only the 300mm wide face is attached to the slab, thus I can't use table 5.6.3 as it is limited to columns with an eff. length less then 3m. My fire actions are 380kN and 195kNm respectively which give an e=513mm! Which means that I can't use table 5.6.4 either cause e must be less then 100mm. Apart from using the Eurocode 2, referenced in clause 5.3.1, how else do I get a fire-rating for this column?
I think this eccentricity limit is a little over the top and should be reviewed, anyone else care to comment?





RE: AS3600-2009 fire rating for columns
RE: AS3600-2009 fire rating for columns
I don't know of anyone that is using AS3600-2009 part 5 for design. See this thread for discussion on this chapter, and note that the committee is reviewing this chapter and other errors. thread744-264534: Fire in AS3600-2009
Rapt, if you happen to pass by, do you know what happened at the committee meeting?
A clear conscience is usually the sign of a bad memory
RE: AS3600-2009 fire rating for columns
RE: AS3600-2009 fire rating for columns
There is supposed to be an amendment coming out shortly to fix some of the problems with the code, while other problems have been referred back to sub-committees to sort out. Presumably they were too complex for a quick fix. Dont know when this will be finalised.
RE: AS3600-2009 fire rating for columns
I noticed that is has numerous tables in Annex C that deals with more variable actions then the single table in AS3600. Thankfully they have a few that require "e=0.5b with e<200mm".
The criteria that e/b =<0.025 ratio is not it the Eurocode either. The Aussies have added in an 0, the eurocode says e/b=<0.25.
Fire-rating for unbraced columns may be found in a "Country's National Annex" according to EC, where is that in AS3600?
Also, why is the a columns effective length different for fire-rating purposes?
RE: AS3600-2009 fire rating for columns
Actually the e/b limit of .25 is in the EC code (I have a draft copy but it should not have changed much) in clause 5.3.3 for Method B which is one of the 2 simplified methods offered in AS3600. It is basically the same as the AS3600 method, both the table and the limitations.
It refers to Appendix C to extend this table to cover more columns and to Appendix B for calculation methods to cover any section (on which both Appendix C and clause 5.3.2 and 5.2.2 in EC are based.
THis is the part that is not in AS3600. I assume it will be covered in the Commentary when it si written (at least I will be trying to get it in there) but I cannot be sure at this stage.
RE: AS3600-2009 fire rating for columns
This is the point of pwht1's post, the usefulness of T.5.6.4 is severely limited.
RE: AS3600-2009 fire rating for columns
RE: AS3600-2009 fire rating for columns
RE: AS3600-2009 fire rating for columns
RE: AS3600-2009 fire rating for columns
You use one of the 2 calculation methods in Appendix B of EC2 if not covered by 5.6.3 in AS3600.