Extending H beams - strengthening?

[Pete.]

the bolts would have to go from the top of the new beam through to the bottom of the old beam to get any strength if you are only bolting to the top of the I beam you have no strength in the beam and it may peel the web off the I of the lower beam

If that was true then you would see through-bolts in every application but I've never seen them ever and I've taken apart many bolted steel structures. Also by doing what you suggest how can you achieve minimum bolt torque without deforming the beam?

If I was doing that with bolts I'd make sure I had plenty of overlap and use six bolts per end at least. If I was doing it with welds I'd cut the beam at about 22 degrees four times and flip the cut out pieces over to make a 44 degree Z shape and weld all around

 

[KemppiFrog]

I was thinking on those lines too, but reconned it would be too much work for the OP, esp as it is in situ. And, at each lower flange joint, put straps over the joint and weld down the edges. Put the welds in sheer, better than tension.
KF

 

[wrinx]

Wish I could do CAD

I've also considered the drawing above bit didn't think it would be very strong...obviously I'm wrong

I'll go get a picture now...

wrinx

 

[wrinx]

First shows the set up, 150 beams going across the 4.5m garage width with c.100mm beams bolted to them running the length. Then there's another 4m length of 150 which runs up and down.

Second shows the vehicle lift.

Third shows the reason for needing to raise the middle third, to get full lift height and park another car underneath.

wrinx

 

[Pete.]

Blimey mate it looks like your rolling beam AND the roof are supported by the RSJ you want to modify.

 

[wrinx]

Roof is just plastic sheet, no weight there at all.

But yes, I'll need to chop down the verticals to suit.

wrinx

 

[Engineer1964]

Can you just not move that beam out the way completely? You say the roof is just Plastic Sheet. I can't see the real reason for having such heavy duty steelwork in place. You can make a seperate jig or assembly for your engine hoist

You can cut out the verticals and put them in at an angle, That should enable you to remove that beam all together

 

[wrinx]

I assumed the steelwork is there primarily for the moving gantry and block 'n' tackle, which is very useful, I wouldn't want to lose it...the previous owner had a habit of over engineering everything.

I think the best and easiest solution is bolting/welding another piece on top...but back to the original question, could I extend the original piece by welding extensions or should I buy a fresh piece a couple of feet longer than the gap?

wrinx

 

[Rudi McAnichal]

Roof is just plastic sheet, no weight there at all.

Hundreds of shed roofs collapsed over the last couple of winters because folk underestimated the snow loads.

 

[wrinx]

A fair point.

wrinx

 

[brightspark]

Hundreds of shed roofs collapsed over the last couple of winters because folk underestimated the snow loads.

and some were trained structural engineers that designed them

 

[Rudi McAnichal]

and some were trained structural engineers that designed them

Wrong kind of snow. Not enough wind to blow it off the roofs.

Many collapsed sheds were big and modern, with low pitch + large gutters that prevent wet snow from sliding off. Apparently actual snow loads were up to five times as high as in the design standards used by structural engineers. Sheds built by peasants 150 ago, with steep pitch roofs, suffered less.

Reminds me that one of this forum’s regular contributors has a line about amateurs, ark, experts and Titanic.