Weep holes for tubular structures

[cybo11]

Ok, I give up. Where in D1.1 does it say tubular structures need weep holes? I can't find anything on it from AISC, either. Any AASHTO comments on it?

Application: A segmented arch pedestrian bridge, HSS 8x8x3/8" A588.

TIA,
Cybo

 

[hokie66]

I assume you intend to galvanize the structure. If you don't leave weep/drainage holes the closed sections will not be coated inside. In addition, they may blow up in the galvanizing bath.

 

[dik]

If galvanised, they're required and if outside, I often supply them to keep trapped water to a minimum for freezing purposes. You can buy little plastic plugs made intentionally for drain holes.

Dik

 

[cybo11]

Not Galvanized. Weathering steel A588 or as I should say A 847 for tubular shapes. The tube segments are approx 8'long and will be completely enclosed via welding. The only real consideration here is condensation inside the tube. I can't find anything to say this needs consideration.

 

[hokie66]

In your case, I see no need for holes. Holes would just be a place for moisture intrusion.

 

[dik]

For weathering steel, staining of surrounding concrete can occur... the assembly can be seal welded as hokie notes; I often put in drain holes just in case.

Dik

 

[apsix]

Completely enclosed via welding doesn't guarantee that moisture will not enter.

From SCOSS; "Although the structural elements are manufactured as 'sealed units', continuous welding does not necessarily produce a complete seal and water may accumulate inside where the units are exposed to the weather".

http://www.scoss.org.uk/popuptemplate_1.asp?pubid=28

 

[ornerynorsk]

Weep holes are very common, can't recall if there's a standard that covers it, though. Experienced structural draftsmen will usually notate the preferred location, size, etc from what I've seen. Don't do a lot of structural these days, though. Someone else is bound to have a lot more info on this.

 

[berkshire]

If this structure is located in a frost zone, you need drain holes.
The accumulated water apsix mentioned will bulge the tubes when it freezes.
B.E.

 

[moltenmetal]

Bulge? Try RUPTURE- we've seen it.

Even if your welders are perfect, someone will later drill an attachment hole for some minor component on a horizontal top surface and there's your water ingress point.

If you're in a climate that EVER freezes, drill the holes!

 

[4Pipes]

I have never thought that randomly sized open holes in a structure that cannot be corrosion protected on the inside are a very good technical solution. It seems perverse that $m are spent on paint specs, grit blasting the outside of struuctures then leaving the inside open!!

Holes are never at the bottom and are often burnt rather than drilled.

As a non-structural engineer, if I were building my own house from hollow sections, I would drill and tap vent holes and use a threaded plastic plug. I would use the holes for inspection and for pressure testing if I was worried about water ingress. I would use the hole for introduction of a vapour phase inhibitor and for the location of a humidity indicator.

 

[samy68]

weep holes are must require for Galvanizing as a train vent to avoid the explosion at kittle during hot both. It is also require during chemical both(cleaning)before hot coating.