HSS closure plates for AESS

[AaronMcD]

I'm designing an architecturally exposed structural steel patio shade structure mostly out of HSS tubes.

The columns and a couple of the beams will need closure plates. First I detailed end plates to match the HSS section, groove the outside of the HSS and weld all around. But I figured it might be easier and look a bit better to inset and groove the plate, then grind the end. I'm wondering for this option how close a steel shop could get the plate to fit. Will there be a gap at the root of the PJP? Is this a problem? The beam end plates will have structural loads, which is why I'd rather use the groove weld than a seal weld.

http://www.hellodwell.design

 

[hokie66]

Galvanized? Remember the zinc drainage holes.

 

[dhengr]

AaronMcD:
What are the sizes and dimensions of the HSS and end pls.? Can they really take much more than a slightly grooved seal weld? Fitting the end pl. into the end of the HSS is tough due to many different tolerance variations. Maybe better to cut (nibble, grind, machine) an outside groove/bevel on the end of the HSS, and cut the end pl. slightly oversized, fill the groove with weld, and then grind to clean up and finish. That way you now the throat size of the weld, and can see the fit-up and root condition before starting welding. What are the loads on these end pls. and what’s causing them? Galvanized or not, do drill some drain holes at the low points. These things have a way of collecting water over time.

 

[kingnero]

A vote for inserts, with the corners cut off (=> think an octagonal plate), with 4 edges beveled (3-5 mm @ 45°).
Dimensional variations can be picked up by welding, after all they shouldn't be that large.
Make those small enough, hold 'em in place using magnets during tack welding, remove magnets, weld all around (except the corners obviously).

 

[Veer007]

If it is a closure plate, must need PJP? why don't you use butt weld all around with grind smooth? Post some images if possible.

Thanks in advance!!

 

[kingnero]

BW with cjp requires more prep, there is more that can go wrong, and your example requires grinding IF the sides are visible for esthetical reasons.
BW pjp "inserts" require less prep, there is no need for a "full strength" joint there, and they are typically used on top of columns, so not visible (you can drop the grinding).
Your example also prohibits HDG, which seems a logical/necessary step to do for an outside patio. OR you need an additional machining (drilling/punching) step.

 

[AaronMcD]

The plates at the tops of the columns will not have load. There are 2 raised HSS beams that but into a beam or a column and will see some small bending moment. Very light loads. Any size structural weld should do the trick. The columns are 6x6x1/4 and the raised beams are 6x4x3/8. I saw a previous thread about holding the plates in with magnets, and was thinking if they are setup for this it might be easier to grind the end smooth than the grind smooth all around the HSS as they would for a cap plate.

They don't want galvanized texture, they will paint the steel. I'd rather not have any holes. The columns are embedded so drainage would be very difficult, and the beams are horizontal so I'm not sure where to locate holes. Holes will look bad on the underside of beams.

http://www.hellodwell.design

 

[XR250]

I am curious why you are expending resources to detail this. Why not let the fabricator figure it out?

 

[dik]

Not really a good idea... I've seen too many HSS tubes split from trapped frozen water. Let the fabricator meet the AESS level required. He knows how to do it, better. For seal caps, you do not need CJP welds.

Dik

 

[AaronMcD]

As for letting the fabricator detail it, I think that would be fine for the non-structural column caps, but the structural engineer is responsible for structural connections. I'll show the inset plate with groove welds and let the fabricator ask for something else if they would rather do it differently.

We don't get freezing temperatures. I was going off recommendations in older threads about sealed HSS.
I guess I could drain the beams in the center but that wouldn't look nice. For the columns I would have to drain through the foundation and out to... somewhere. An underground aggregate pit wrapped in fabric?? Maybe a typical HSS base drain hole and put aggregate over the foundation, but I wonder if that would tend to collect water as much as it would drain water.

http://www.hellodwell.design

 

[dik]

Dik

 

[r13]

Mount your column on the floor slab, and provide small vent hole.