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Carport question... W-beam related... metal guys step in.

DFW Rusty

Well-known member
May 21, 2020
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Do y'all think that W12x30 Beam will self support over about 28' with some purlins welded to it and some roof tin? No snow load, this is in Texas, 1/12 pitch.
Yeah, I personally think its overkill. Every ~20ft carport I built was drill stem and purlin, and they're still standing.

That is what I keep seeing, was at a buddies house last night and his carport was made of angle iron, purlins and drill stem it was a 30x40 and it's old as shit. I always over kill everything I build (house wise), this go around I am trying to go middle of the road. What would you use to span about 28'?
You realize that beam is going to weigh about 840lbs. Right?

Seems BIG
28 wide by x? The other dimension is important to figure how much roof it's holding. Whats your column design?
Here are the dimensions of the beam for those who are interested but don't want to look it up

Screenshot 2021-02-23 110444.jpg
we span 30' with 10" perling, and this has held up to a wet 42" snow load. 1' drop over 22'. but it did have a blocking run in the middle.
One half of my brothers 24x24 carport collapsed last week from the snow. It was built out of 8" cee purling. A lot of similarly built carports did too.

The half that survived had a wall on it that strengthened it up a bit.
These are really crappy scans. For what ever reason, I can't print to JPEG anymore from anything.... So I had to print it and then scan it to a JPEG.

On the plan view, the 8' section is free floating purlins that will butt up to my house with a receiver purlin and it has to be 8' because I have a 90" wide porch section along that wall.
On the right there is a 5' free floating section that is on the beam, 27' span and then a column with 5' hanging off (beam is approximately 32' long). This is a really rough sketch. Not going to invest much time until I decide what materials I want to use.

50974156782_358a60a784_c.jpg img010 by dfwrusty, on Flickr

50973358878_b3fbf539cc_c.jpg img011 by dfwrusty, on Flickr
i would frame it all with 10" c purling, and never worry about it. my car port in Colorado is 30 wide 22 deep 4 post one on each of the corners
If I understand what you're asking and the beam is old and only A36 then it can support 780 pounds per linear foot, and since only half of the 8' span is on it that's 195 PSF with about 1/2" of deflection in the middle.
Send it. It would even work up here.

I should mention that load is for tolerable deflection according to aisc 9th edition, and still a ways from yielding. The beam is also more likely to be 50ksi unless it's ancient.
You should match or exceed your columns and their supports to the strength of the W-beam if you can.
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