lightly loaded column base plate attachment

[SteelPE]

I am designing a set of stairs for a client/fabricator. It is your standard set of switch back stairs that is going in what appears to be a small industrial building.

The owner of the building is also the tenant and during the construction they decided they wanted to use a radiant heating system. We have to support the stairs off of columns that rest on the existing slab. The loads are quite small (max col. reaction = 5.0 k). The typical detail would have us expansion bolt the bottom of the columns to the concrete slab. However, since there is a radiant heating system in place this is not possible.

I am in the process of getting the thickness of the SOG. I have been told that it is 6” thick but I am going to verify.

The fabricator is suggesting using epoxy to attach the column to the slab. Has anyone done a similar detail? This doesn’t seem like a bright idea but I thought I would throw it out there.

 

[azcats]

I tried to do something similar with PVC posts/plates supporting a fiberglass floor grid in a corrosive environment. Never could get enough product/material data to justify it properly.

Perhaps you could roughen the surface of the concrete and pour a small pad/pedestal with bolts for the column. A bonding agent between the two would provide pretty good adhesion.

 

[bones206]

You could look into using undercut type anchors or concrete screw anchors, which will generate smaller expansion forces.

 

[SteelPE]

bones,

The concern is not about the expansion force associated with the anchor but with the fact that you have to drill the anchor into the slab. There is a chance that when you drill into the slab you will hit one of the pipes requiring some expensive repairs.

 

[vmirat]

Unless you're in a high seismic region, the stairs won't have an uplift load, so the only thing your trying to prevent is lateral movement (hence the practice of using expansion anchors). I would make sure that the stair frame is rigidly tied together so that the columns don't have to rely on the floor for lateral stability (use X bracing or something). Then, I would try to tie it back into the walls or rely on the upper floor deck. You could also add epoxy to the base of the columns including drilling a series of holes in the baseplate so that the epoxy oozes up the holes and provides additional lateral anchorage. The only other suggestion would be to do sonic investigation to try and locate the tubing in the slab.