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Temperature differences during structural steel construction

Temperature differences during structural steel construction

Temperature differences during structural steel construction

(OP)
There is a statement in the masterspec go-by for structural steel framing that reads, "Make allowances for difference between temperature at time of erection and mean temperature when structure is completed and in service."

What specifically would you expect the steel sub-contractor to do in order fulfill this requirement?

RE: Temperature differences during structural steel construction

See Table 17-11 in the 13th edition AISC Manual. The Coefficient for Thermal Expansion for mild steel is 0.0000065/deg F. The example in the manual has a 40 ft. long steel member expanding 0.0078 ft (0.094") for a 30 degree F temperature change. The structure should have been designed to accomodate any expansion or contraction of the steel. Accounting for steel expansion/contraction due to temperature change should be the design engineer's responsibility (see Section L7 of AISC 360), not the steel contractor.

RE: Temperature differences during structural steel construction

Bearing alignment is the first thing which comes to mind. If you are erecting in the middle of summer at close to the max expected temperature, you wouldn't want the bearings at the middle of the movement range.

RE: Temperature differences during structural steel construction

In a similar light, does anyone have an idea of how hot steel bridge members or outside crane beams, subject to summer sunlight gets? This would be in the northern states, N.Dakota, Minnesota, etc.

Dik

RE: Temperature differences during structural steel construction

In Texas I have seen 20 degrees F above ambient, but this is incredibly variable depending on the exposure, steel thickness, angle, wind, solar insolation, et cetera, et cetera.

RE: Temperature differences during structural steel construction

Technically, I think that means that whatever the temperature range is for the steel of that finished building, the steel temp when installed should be within that range, since you as the EOR should be designing for the expansion/contraction in that range. Notice I say the steel temp and not the building temp, because if you have roof beams in an insulated plenum space then they may end up being a lot hotter than ambient temp, depending on the insulation and roof type. Floor steel beams and columns I would guess would be closer to the average building temp. So that could get really complicated, really fast, if you have several temperature installation ranges...

But I would be interested to see what others' experiences in this are, because it has never been brought up in any of my projects even with an expansion joint. I would think it would depend a lot on the type of structure, how big it is, expansion joints, and weather variances. Maybe it is a CYA thing in case they set steel on a record breaking cold/hot day?

RE: Temperature differences during structural steel construction

a2mfk:

The steel is exposed to sunlight and is totally exposed. Ambient temperature generally ranges from +30C to -40C and I was wondering if there are any guidelines from bridge or crane runway people that may have info on the temperature rise due to sunlight exposure.

Dik

RE: Temperature differences during structural steel construction

if ambient is +30, rail temp. can rise up to 65°C.
Over here we have -15 to +30 ambient, and rail can go as cold as 15 degrees lower and considerably higher.

RE: Temperature differences during structural steel construction

Thanks Kingnero... higher than I thought... I was using 50C, but was a WAG...

Dik

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