Using embedded angle to resist 4

[canwesteng]

My mechanical engineer has conveniently ordered a pump without a sub base, and now the impeller housing which is 4" away from the anchors is below the top of concrete. Breakout of course doesn't work, so I'm thinking of embedding an angle with rebar welded to it and lapped to the foundation bar and designing the embedded angle for moment. Does this make sense?

 

[WinelandV]

I think that can work, but I also that you need to start to develop l[sub]d[/sub] behind the shear breakout cone.

If that was already your intent, please disregard.

Please note that is a "v" (as in Violin) not a "y".

 

[canwesteng]

The intent is to lap the bar with the foundation top bar

 

[WinelandV]

This is what I meant (green line is the foundation top bar):

Just want to make sure you don't start measuring the lap distance until you're past the breakout cone.

Please note that is a "v" (as in Violin) not a "y".

 

[driftLimiter]

How are you planning to demonstrate that the full tensile capacity of the bars that are welded to the angle is going to be developed?
If you look at it like anchorage reinforcement, the goal is to develop the anchor reinf. on each side of the failure surface. I'm not saying it can't be done but what calcs will show it?

 

[KootK]

PCI manual will probably be your friend here. I think that they have tabulated setups for rebar anchored by welded end plates which is basically what this is.

 

[phamENG]

Any reason not use hairpins or other, 'traditional' anchor reinforcement schemes?

 

[dik]

...often with a bent strap with a 90deg bend welded at 45deg or a headed stud at an angle. The bent strap is/was common.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[canwesteng]

I don't see any issue developing the full tensile of the rebar, the weld is stronger than the bar, and it can be lapped with top bar in the foundation.

 

[driftLimiter]

@cantwesteng. Okay you can weld the rebar to the angle. Are you sure the angle will get enough bearing on the conc. to develop that yield force of the bar? Thats what I am really asking.

 

[dik]

dL... that's part of the connection design process, I would think...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[driftLimiter]

Yes I think so too. I am curious how the calc is supposed to be setup.

I visualize basically a distributed load on the vertical leg of the angle.
That load is limited by the concrete bearing, and the angle bending.

 

[canwesteng]

The loads are really quite small, 11k factored. The bearing works on about 6 sq. in. of concrete. For hairpins, I've never seen published info on how they work, and personally don't like relying on the anchor bearing against the bend of a bar. For strapping, the load path to me seems much messier than this. Good suggestions all around though.

 

[Rabbit12]

https://ascelibrary.org/doi/abs/10.1061/41130(369)225

Design of Anchor Reinforcing by Widianto, Patel, Owen is your friend. I wouldn't mess with that angle unless I'm missing something that makes ties not possible. Your adding costs and complexity that's not necessary.

 

[AgMechEngr]

Is designing a base to lift the pump so that you can increase your edge distance an option?

 

[canwesteng]

Designing a base to lift the pump is the correct option. Unfortunately the ship has sailed, and we need a fix today.

 

[driftLimiter]

The paper that @Rabbit12 posted, and example 4 of AISC Design Guide 1 demonstrate hairpins usefulness.

 

[canwesteng]

That paper shows hairpins around vertical pier bars, not around anchors as I've seen others do.

 

[driftLimiter]

Yea I guess neither of those really show what you are asking. I know I have seen a reference for hairpins. I will dig around and see if I can locate it.

 

[driftLimiter]

The Design Guide #7 Elaborates a bit more on anchor reinforcement.

Also shows this figure which you might find useful. Seems there is definitely precedent for this method of anchorage reinforcement.

Pretty good examples in this design guide regarding shear lug design, good commentary on Hairpins.