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steel canopy - anchoring into the existing structure

steel canopy - anchoring into the existing structure

steel canopy - anchoring into the existing structure

(OP)


I'm designing pretty big steel canopy next to the existing residental buidling.
I am planning to anchor steel beam (blue in image) to existinc concrete wall.
Since vertical reactions at the end of the beam is quite large = 45 kN I'd like to anchor it as shown in attached sketch. That way I get shear forces only (on the bolts) right? So I have to control welds (beam - plate), bolts (shear) and steel plate (to shear).

Thoughts?

Any other/better solution will be appreciated



RE: steel canopy - anchoring into the existing structure

You’ll get some tension in the anchor bolts too because the connection is semi rigid.

RE: steel canopy - anchoring into the existing structure

(OP)
what if I use only one row of bolts instead of 2?

RE: steel canopy - anchoring into the existing structure

You get horizontal force and tension force due to the bracing too ...

RE: steel canopy - anchoring into the existing structure

(OP)
Yes, I do but they are not that large.

RE: steel canopy - anchoring into the existing structure

You should have no problem with that load into the wall. (4) 3/4" Hilti anchors should be able to handle the 45 kN and achieve some tension capacity as well if you need it. If you want to weld the tube to the plate you can just weld each long side to the plate and leave the tops un-welded. You should be able to develop 45 kN over the length of those welds. I would also spread the anchors out vertically as much as you can to reduce their interaction with one another.

If you have other shear/tension forces from the braces I would include those unless they are legitimately negligible.

Check out the anchor capacity with the Hilti profis software. As long as you have no edge distance issues in the concrete I believe you can handle those loads no problem.

RE: steel canopy - anchoring into the existing structure

I agree with Tomfh,
The beams will rotate under load, and this will cause tension in the bolts whether you have 4 bolts or 2.

That tension should be included in the design of the bolts along with their shear forces.

Another idea would be to bolt on a plate to the wall, then weld on a perpendicular single plate shear connection with horizontal slotted holes - allowing some rotation and negating rotational bolt tension.
That detail, though, doesn't allow for any axial tension in the beams to pull on the connection, or wall; so any tension on your overall framing from wind would have to be taken some other way - or you simply include it as direct tension in your bolts.

RE: steel canopy - anchoring into the existing structure

Use a larger, thinner plate for your connection that will flex before it puts too much prying action into the bolts.

RE: steel canopy - anchoring into the existing structure

Yes a more flexible plate that cannot develop significant tension in the anchors is a neat way to do it.

RE: steel canopy - anchoring into the existing structure

So I presume that there will be some kind of load on top of this structure?
Larger plates would be a very good idea.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

RE: steel canopy - anchoring into the existing structure

1) The flip side of using a flexible plate to limit connection moment demand is to use a stiff member. Things look a lot different at L/480 than they do at L/90.

2) For me, the difficulty with thin plate path is estimating how flexible the damn thing actually is. By the time that you're suitably conservative on plate bending and prying behavior, you often wind up back at "pretty stiff". And the thinner the plate, the more the prying action factors in.

3) On occasion, I've used a single row of bolts and small plate washers behind the connection plate to try to encourage pin-ish behavior. I'd not want to do that on a connection like this with aesthetic implications however.

RE: steel canopy - anchoring into the existing structure

Don't you have lateral load? The rebound of wind from the building wall can push the canopy outward and create instability, not to mention earthquake effect.

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