Weird gap in PEMB frame

[theonlynamenottaken]

I was on a scissorlift looking at a gym PEMB frame last week. It was fabricated and erected ~late 60's - early 70's. It is a typical bent with tapered columns and gabled, tapered beams. The clear span is about 108'.

At the column-beam joint there is an odd condition I've never seen. There is a vertical web stiffener, a horizontal stiffener (parallel to floor) and a diagonal stiffener. The horizontal stiffener is basically the extension of the beam bottom flange through the column web. On the upper face of the horizontal stiffener (beam bott flange extension) the web above is only welded to the stiffener for the interior 9" of the column's 49" depth. For the remaining 40" there is an 1/8" gap between the web and the stiffener/beam bott flange.

It did appear to be intentional, though I've never seen anything like that. I haven't checked yet but I feel that the 9" of connection will be adequate for wind pressure on the column (at a height of 20' and 25' frame spacing). The column flange connections are robust and surely will handle the couple...

But has anyone seen anything like this before and care to explain?

 

[MWPC]

As I understand your post, the top of the stiffener is welded for 9". Is the bottom of the stiffener welded to the column web? Ken

 

[theonlynamenottaken]

All 49" of the column web is welded to the stiffener on the bottom face.

 

[hokie66]

Sounds like it was intentional, designed that way. The first part of the stiffener takes the greater load, then it dissipates into the web. Might have done it that way myself, except think I would have put the continuous part on top so as not to provide a trap for moisture.

 

[DaveAtkins]

I bet it was designed that way. PEMB suppliers design things VERY precisely--for example, they will use a .235" thick web plate instead of 1/4".

DaveAtkins