Fire rating of steel
Fire rating of steel
(OP)
We need to strengthen an existing concrete beam by providing a supplementary support steel beam below it packed tight, in a parking garage whose size is such that the structural members require a fire rating. Is there any way to avoid the fireproofing of the steel beam by designing it to have more strength than required?






RE: Fire rating of steel
What's the reason to avoid fireproofing?
If it's aesthetics (for a parking garage, I doubt it), look into intumescent paint. But it is expensive.
RE: Fire rating of steel
RE: Fire rating of steel
Concrete fireproofing around the beams I suppose would solve all problems, by a) providing corrosion protection, b) robustness against damage and c) fire protection.
Any comment?
RE: Fire rating of steel
Dik
RE: Fire rating of steel
Given the exterior exposure, both the steel and the intumescent paint would need protection from the environment. Like dik suggested, talk to the paint supplier. For severe exposures, it is better to go in for a weather resisting steel rather than counting on the paint to provide both, the fire and the environmental protection.
If you have the luxury of encasing the new structural steel in concrete, then go for it.
RE: Fire rating of steel
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Fire rating of steel
RE: Fire rating of steel
The newer technologies are not expensive and can be easily applied using any good primer under them and anything you like as a top coat, so very versatile. Depending on the need, I know of a handful that would fill the bill here, but I don't think I'm supposed to mention names, so just do some homework. Two I can think of are in Indiana, one in in Connecticut and more are coming along. Wait till the new developments in nanotechnology hit. These will deliver products that offered increased performance the longer they're exposed to fire. However, getting back to the here and now, Insurance companies like Grinnell Mutual have been doing research on these new coatings and have made some interesting discoveries.
As for the cement board idea, cement board is an extremely efficient conductor of thermal energy, so that would probably be counterproductive - and an excellent point is made about the fragile nature of cement board from vandals, but also just common impact damage from car doors, etc.
I would recommend finding something newer with more advanced features and treating both the steel and the concrete. Bottom line, there are products out there that solve all of these problems very elegantly and affordably without the problems and hassels that have been accurately described here, but relative to older approaches that are largely outdated.
RE: Fire rating of steel
To Tindy - yes I have spoken to a fire protection company and they have intumescent paint and also a sprayed cementitious coating that could be used in parking garages - I will have to double check with them whether the intumescent paint is ok for the garage, but they do know it is an open air garage. Both these sytems can be used with a compatible approved zinc rich paint for corrosion protection. Yes I am very aware that intumescent paint is very costly.
Yes, cement board is not appropriate for a number of reasons cited here and I think that the project manager is finally recognizing that!!
Thanks all for the great comments. Much appreciated.
RE: Fire rating of steel
Be wary of cementatious or spray applied cellulose. The Miami-Dade cultural center, the new convention center in San Juan and other places are experiencing extreme damage to the structural steel post application. The problem is that the damage can be hidden until it has become a very serious problem. Intumescents are now at the point that more obsolete approaches aren't really relevant. It reminds me of when 4' of goose down got replaced by 1/8" of 3M Thinsulate.
RE: Fire rating of steel
Andy
RE: Fire rating of steel
RE: Fire rating of steel
RE: Fire rating of steel
@ajk1 - Keep us posted about the solution you finally adopt and also any additional info you may acquire about intumscent paint.
RE: Fire rating of steel
RE: Fire rating of steel
RE: Fire rating of steel
RE: Fire rating of steel
RE: Fire rating of steel