Welding I-beams together

[bdog]

I am building the rafters for my carport. 12” 14# W beam with a 4/12 pitch. Span is 29’

I have built multiple steel buildings but all had a single pitch roof and I have never had to weld beams together like this.

Does this look adequate? I am not sure if I need to fish plate it or need more reinforcements.

Disregard the grey oval plate on the bottom. The beams are just resting on it.

 

[Industrial Toys]

I am having a hard time telling if the plate is on the side or on the bottom to make a triangle.

Now the picture makes sense to me. I wasn't even seeing it in the right perspective. It looks good to me, but I probably, doing everything overkill, made the triangular plate a little bigger. Even slightly bigger would make a HUGE difference and weld strength not as important.

 

[RNeumann]

Probably fine in Texas (no snow) as long as the roof is only seeing “normal” dead loading (use regular roofing material) and minimal live loads - no helicopters or elephants up there.

This assumes you are making at least 4 of these......how many are their? Or what’s the slab in the other direction?

 

[Tractor Seabee]

Now I would put a fish plate on the opposite side from the butt weld. The plate would not need to be welded all around.

Ron

 

[bdog]

Probably fine in Texas (no snow) as long as the roof is only seeing “normal” dead loading (use regular roofing material) and minimal live loads - no helicopters or elephants up there.

This assumes you are making at least 4 of these......how many are their? Or what’s the slab in the other direction?

It is a 29’ span for the I-beams and then 26’ in the other direction. There are only two of the I-beam structures. The purlins going crossways will be 10” C purlins and then it will be sheeted with 26ga R panels.

The material sizing and spans were chosen from the steel building suppliers chart and were chosen toward the larger side of materials. I am not really concerned about the material size rather just the weld.

 

[bdog]

I am having a hard time telling if the plate is on the side or on the bottom to make a triangle.

Now the picture makes sense to me. I wasn't even seeing it in the right perspective. It looks good to me, but I probably, doing everything overkill, made the triangular plate a little bigger. Even slightly bigger would make a HUGE difference and weld strength not as important.

The triangluar piece is cut out from a 4” I beam I had laying around. I didn’t have any extra of the 12” or anything larger on hand to make the piece with.

 

[RNeumann]

It is a 29’ span for the I-beams and then 26’ in the other direction. There are only two of the I-beam structures. The purlins going crossways will be 10” C purlins and then it will be sheeted with 26ga R panels.

The material sizing and spans were chosen from the steel building suppliers chart and were chosen toward the larger side of materials. I am not really concerned about the material size rather just the weld.

So the purlins span 26’? That’s more load than I was expecting.......

 

[bdog]

So the purlins span 26’? That’s more load than I was expecting.......

Yes - they span 26’.

8” purlins are good to 25’ and 10” are good to 30’. I am barely over 25’ but went with 10”.

My last building was a single slope but was 15’ spanned by the beams and 25’ spanned by the purlins and I used 8” 10# W beam.

 

[SandburRanch]

If the weld shows a root bead on the back side as in pipe line welding you'll be good. If not grind/clean the back side groove with the angle grinder and run a bead in the back. Don't be surprised if the mid section of the beams draw in to give a slight inward bow. Hopefully not.

 

[mikester]

I am building the rafters for my carport. 12” 14# W beam with a 4/12 pitch. Span is 29’

I have built multiple steel buildings but all had a single pitch roof and I have never had to weld beams together like this.

Does this look adequate? I am not sure if I need to fish plate it or need more reinforcements.

Disregard the grey oval plate on the bottom. The beams are just resting on it.

View attachment 603007

All your stresses are in the flanges not the web. Your picture only shows the web.

The question is if you have to ask people on an anonymous tractor forum if your structural welds are good enough for a building then you probably have bigger worries like ‘is this building going to fall on my head - or my grandchildrens heads - or the neighbors...’

 

[Streetcar]

All your stresses are in the flanges not the web. Your picture only shows the web.

The question is if you have to ask people on an anonymous tractor forum if your structural welds are good enough for a building then you probably have bigger worries like ‘is this building going to fall on my head - or my grandchildrens heads - or the neighbors...’

Great response.
The building can get large wind loads.
With the peak in the roof,you have different loading than simple beam
Definitely need fish plates on flange.
With only two beams the structure has fracture critical welds. One mistake on the beams and the whole thing falls

 

[bdog]

All your stresses are in the flanges not the web. Your picture only shows the web.

The question is if you have to ask people on an anonymous tractor forum if your structural welds are good enough for a building then you probably have bigger worries like ‘is this building going to fall on my head - or my grandchildrens heads - or the neighbors...’

I am not really doubting my welds. I have built a half dozen steel buildings since the mid nineties and all are still standing today. One in particular survived a tornado that did considerable damage to the house less than 100’ away. I have also welded lots of scary things like trailer hitches, gooseneck conversions, pintle hitch plates, on dump trucks, etc.

I simply have never had to join I-beams together like this before and was just asking for advice on what reinforcements if any were necessary.

 

[yomax4]

Mine are similar and they have fish plates anywhere the I-beams are joined. Good luck with the new building.

 

[CADplans]

My 57 X 48 "L" shaped shed has a welded frame,, I fish plated every joint I could,,

The only wood fastened in my building is the flooring in the upper storage area,,

The building has been up for 20 years,, and gone through at least two 36" snows,,

 

[Streetcar]

Bdog
You have picture if welds on web. Flange will have highest stress.
Because of the angled joint , you will have buckling stress in web.
Both areas should be reinforced with fish plates

 

[bdog]

I added some plates on the side. Coupled with the extra portion of an I-beam on the bottom I think it should be fine. I stood each truss up vertically on the ground and got triple pass welds across the top flange and on the insides of the bottom flange.

We got the trusses in place today. Only got two purlins up before we had to call it a day. Hopefully will finish most of the welding tomorrow.

 

[Streetcar]

Bdog
How are beams attached to columns?

 

[bdog]

Bdog
How are beams attached to columns?

The beams are sitting on top of the columns (which are made of the same material) and they have 40” of weld securing them.

 

[Industrial Toys]

Now that I see the erected structure, I would say the welds in question are quite important. If the outer ends were erected so they had no place to go outward, then there would only be compression between the two beams at the top.

 

[3Ts]

FWIW: My barn is built with trusses that are done the same way and is a 40' span spaced 20' apart. Also 12" beams although I don't know the weight. - and no reinforcing plates. I'll see if I can get a picture tomorrow.