Steel Deck Buckling with Loadbearing Precast

[Fuzzy]

We have a large (500,000sqft) warehouse with loadbearing precast and steel decking. In areas where the roofing has not been completed along the outside edges, we are seeing the metal deck welds popping due to the thermal expansion of the deck. It would appear that the precast is holding the decking from expanding (continuous trimmer angle welded at 3' o/c to precast).
Has anyone run into this problem? Will it go away once the deck is insulated? Cut trimmer angle to reduce the concentration of the buckling?
Any assistance or information of previous projects with this problem would be greatly appreciated.

 

[UcfSE]

Does the roof have any expansion joints? At 500,000 ft[sup]2[/sup] I would think you should have an expansion joint in there.

 

[Fuzzy]

The roof is divided in half with an expansion joint. Each half is roughly 600'x500'.

 

[JAE]

Is the weld damage in areas where the deck is spanning into the precast or where the deck is parallel to the precast? Also, what is the overall length of the support angle along the precast walls? I'm assuming it is continuous with welded splices?

 

[Fuzzy]

The welds are popping where the deck runs parallel to the precast. The support angle is continuous with welded splices (600' long). The popping is occuring in about the center of the outer bays (40' bays).

 

[jike]

I assume the cont. angle is serving not only as the collector but also as the diaphragm chord. If the cont. angle is the diaphragm chord, then it should not be cut!

I assume the deck is in the sun with the angle underneath and the precast in the shade.

You mention welds popping and also the deck buckling. How often is the deck buckling? Does it pop the welds in the center of a deck span and then buckle upward?

I am not sure if screws or pins may allow more "slip" to allow the deck to move a little more to accomodate the expansion.

Another idea might be to provide a short intermittent
"deck expansion joint" over a support every so often, perhaps only out 2 to 4 feet or so from the wall. This would have to be detailed properly to still allow the diaphragm to work.

 

[Fuzzy]

It appears that the problem is related to the temp when the deck was completely welded. Decking areas which were welded in hot weather have not had the same problems as buildings which were welded at a colder time. The decking which was rewelded in hot weather has not seen any further popping.