Bolted Connection

[andyfabian]

I am curious if anyone has a rule of thumb capacity that could help. The situation is the following:

1. It's a curtain wall system that has C6 channels at 6'-0" c/c that are connected to stiffener plates along the length of the spandrel.
2. The plate has horizontal slots for fit-up.
3. We could specify tack welding the connection after fit-up to assure no horizontal movement, but are seeking to avoid welding if possible.
4. We don't want to specify SC-bolts because it's a waste for this condition.

My idea is to find a maximum load for the connection that may be minimal, but will allow us to not have to weld. In other words, let's say for argument's sake, is there somewhere that says that bolts installed by "The Turn of the Nut Method" typically can handle 500#/bolt before the plates slide and engage the bearing condition of the connection.

If this is not clear, let me know.

Thanks in advance.

Andy

 

[rholder98]

Perhaps I don't fully understand, but couldn't you forego the horizontal slots?

And do you not need vertical slots to account for deflection of the horizontal member?

 

[samdamon]

Andy- Predicting the load at which a bearing-type A325 is consistently going to move into bearing against the sides of the steel holes is not feasible in my humble opinion. If you have horizontal slots a SC type bolt at this connection really might be best to forestall any movement of your curtain wall laterally.

If your loads are not high and the thickness of the C6 web and plate you are attaching to are not too much, consider using heavy self tapping screws to finish off the connection rather than using high strength bolts. Believe you can fasten up to 1/2" total thickness with the heaviest of these self-tap screws. You could avoid welding that way. If you do use the screws, the bolt(s)could be considered a temporary erection aid, and in that case I think it would be appropriate to use a bearing-type HS bolt, perhaps even an A307. (As you are probably aware even a temp connection has to have some strength though).

Hope this helps.

 

[samdamon]

Good question about vert movement from Rholder- Andy, what sort of vert movement do you expect in the spandrel? Is it taken care of on the other end of your C6's?