Wind load on covered pipe bridge 1

[WARose]

I got a pipe bridge that consists of a couple of 10' x 10' towers supporting what is essentially another 10' x 10' "tower" (running horizontally). Basically the frame is all HSS members. It is very stiff as there are HSS members running between the columns bracing it up. (Almost like a lattice tower except they are connected by welding).

I am uncertain of the wind loading to apply. If it was uncovered with deck.....the answer would obviously be loading it on a member by member basis or per "Signs & Lattice Frameworks" provisions in Figure 29.5-2 in ASCE 7. However, since this thing is completely covered in deck, I'm unsure as to whether to treat is like a enclosed structure, use the provisions in Figure 29.5-1 (i.e. a chimney, tank, or rooftop equipment), or perhaps even treat it like a sign (i.e. the provisions in Figure 29.4-1).

Your thoughts?

 

[hokie66]

Sounds very much like a sign structure to me. Sort of like an overhead highway signage gantry.

 

[WARose]

It kind of reminds me of a sign as well. I'm just having my doubts because it's not thin like a sign.

 

[SAIL3]

is the 10'x10' totally enclosed by cladding?...if it is, I would treat it like horiz ductwork with Cp of 1.3..

 

[WARose]

is the 10'x10' totally enclosed by cladding?

Yep. Except for the ends. (So the pipe can run.)

if it is, I would treat it like horiz ductwork with Cp of 1.3..

Good point.

 

[dik]

An old publication, and based on experimental work done by the Swiss in the 50s and 60s. Used to be part of the Canadian National Building Code. See 20 & 21... lots of irregular shapes.

Dik

 

[SAIL3]

on further thought, just in case the OP is designing to a knat's eyebrow, make that a Cp=1.4, 0.8 windward, 0.6 leeward...