Structural steel design in sub-zero temperatures
Structural steel design in sub-zero temperatures
(OP)
I have to design a small 15,000 sq. ft. single storey freezer building. (25 ft. height steel building with metal roof deck and insulated wall panels).
The operating temperature inside will be -50 deg F (-45 Celcius). Assuming summer construction, the differential temperature will be in order of 120 deg F (65 deg C). The building is completely insulated (walls, floors and roof).
Are there any design guidelines I need to follow? Any words of wisdom? Any good details I should consider from your past experiences?
I appreciate your help.
Daria
The operating temperature inside will be -50 deg F (-45 Celcius). Assuming summer construction, the differential temperature will be in order of 120 deg F (65 deg C). The building is completely insulated (walls, floors and roof).
Are there any design guidelines I need to follow? Any words of wisdom? Any good details I should consider from your past experiences?
I appreciate your help.
Daria






RE: Structural steel design in sub-zero temperatures
RE: Structural steel design in sub-zero temperatures
RE: Structural steel design in sub-zero temperatures
1. An operating temp. of 50 deg. F is not a freezer, but a cooler. There is a big differance. The floor slab of a cooler does not need to be insulated, but be sure to have a good vapor barrier.
2. All joints in the insulated panel system must be well sealed and stagger the joints between insulation layers. Warm, moist exterior air that infiltrates into the cooler will cause condensation. I've actually seen it rain in a cooler that was not sealed tightly!
3. As noted, there are specialty firms that design and build coolers. Usually the enclosing building is a conventional design with a cooler built within it.
RE: Structural steel design in sub-zero temperatures
RE: Structural steel design in sub-zero temperatures
Sorry, my bifocals weren't bifocalling! (:{ You can also forget about the rain inside the unit, it will be too cold to even snow! <G>
Frost heave of the subgrade can be a concern and so the thickness of the insulation under the slab should be looked at carefully.
RE: Structural steel design in sub-zero temperatures
Below the slab on grade, we have 6" rigid insulation on a sand bed that is heat traced. The steel columns go through all this sub-grade onto the concrete piers below. But the column base plates have to sit on a +/- 8" thick wood block acting as an insulator to prevent condensation at the base of the columns.
RE: Structural steel design in sub-zero temperatures
In Canada we have structures (Operating Plants) that are exposed to ambient temperature that you are looking at (-45 deg C) and we have no problems with the serviceability condition of the structure. One thing you have to keep in mind is that all your steel is exposed to the same temperature, threfore the shrinkage is small relative to each of the steel members (assuming that the steel members are relatively the same length). Having said that, you have to look closely at the interface of disimilar material.
If you are still in the early stage of design, I would consider designing this structure "inside out". Instead of using the insulating cladding on the outside of your structure, use it on the inside of your structure. You're find that you will have a very unique looking building. I have one of these in my plant.
RE: Structural steel design in sub-zero temperatures
All bolts outside the building freezing envelope should be regular ASTM A325 or ASTM A490 high-strength bolts, and all bolts in the freezing envelope are ASTM A320 L7 low-temperature, high-strength bolts.
Cheers
RE: Structural steel design in sub-zero temperatures
The building is actually being constructed in Ontario, Canada. The entire structure is a freezer building, so I cannot consider the "inside out" concept, otherwise all structural steel will be exposed.
We are thinking of designing the entire building out of heavy timber construction using Parallam beams & columns (coefficient of thermal expansion is about 1/4 to 1/5 of steel).