Return to index: [Subject] [Thread] [Date] [Author]


[Subject Prev][Subject Next][Thread Prev][Thread Next]
I have a question regarding composite steel-concrete beams 
(concrete slab over steel beam), under fire conditions. I woud 
like to know how  to determine the thickness of the material 
thermal protection for the steel beam. 
Thicknesses are given for the tested assemblies in the UL listings, which are available online at You can then use the weight or area to perimeter ratios to adapt those listings to other shapes.
Another question: Is it possible to use the UL test results for 
restrained beams (which is based on deformation limit, I think), 
in any situation? 
As a general class of construction, steel framing can be designed using the restrained ratings given by UL. restrained means there is resistance to thermal expansion of the steel, which tends to increase the fire endurance of the structure.
The classification of steel construction as restrained is documented in ASTM E119 Table X3.1. There will also be a paper in the next AISC Engineering Journal by Emile Troup and Dick Gewain that further justifies the use of restrained ratings in determining the requirements for fire protection in steel structures based upon past and current fire testing of steel structures. Check out that information before you let anyone goad you into using unrestrained ratings, which can require twice the fire protection and spend a lot of the owner's money in a hurry.