Two post lift shakes roll up door

[Kaizen]

Noticed with zero wind and my f150 on two post that the roll up door rattled when I test shake the truck. Anyone else notice this?
Atlas 10k 2 post
6” 4K psi Alaskan slab
Only place lift touches structure is at flex electrical connection.
No cracks in slab and joints are three feet away. Lift is 15 ft from door.



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[uscarry45]

Is their any other connection to the building and the lift besides the floor concrete?

What is roll up door made of?

 

[Kaizen]

Is their any other connection to the building and the lift besides the floor concrete?

What is roll up door made of?

Nope lift is just connected by bolts.
Door is steel. If not usual I will put a laser on the post and see if the connection of flex connector is doing it. Used flex pipe so it would move. Don’t think lift could flex the whole concrete pad and stem wall to move the structure.


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[kaymccampbell]

That sounds impossible. Eagerly awaiting further reports.

 

[Kaizen]

That sounds impossible. Eagerly awaiting further reports.

No kidding. First time it was wi day so chalked it up to that. Today zero wind so thought I’d ask wtf is going on. Most likely scenario is post electrical connection is not flexing and pushing on truss which then pushes door wall. Hard for me to disprove that alone. Maybe some video tomorrow on the post


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[Garett]

There lots of surface area on the truck. Shake the truck, it moves the air which in turn rattles the door.

 

[cvairwerks]

Could be a hollow under the slab....Found one under part of my driveway when moving a one ton tool on a pallet jack. Felt the slab move when I go to the unsupported corner.

 

[Kaizen]

There lots of surface area on the truck. Shake the truck, it moves the air which in turn rattles the door.

I had open windows and roof vents are open. 1000 sq ft garage. If it was all sealed I can see how it would do that


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[Kaizen]

Could be a hollow under the slab....Found one under part of my driveway when moving a one ton tool on a pallet jack. Felt the slab move when I go to the unsupported corner.

I was there for the pour. Can’t see how there could be a void unless soil settled. This side has no crack on expansion joints at all. Other side does have normal hairline crack on joints


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[cvairwerks]

No cracks in mine either, but definitely a huge void there. Poor prep work and the PO doing something stupid caused my problems.

 

[nadogail]

Alaskan Slab in New England?

I am aware that concrete does not always stay where you put it; but for a slab to move from Alaska to New England boggles my imagination.

Please add to my knowledge.

 

[Kaizen]

Alaskan Slab in New England?

I am aware that concrete does not always stay where you put it; but for a slab to move from Alaska to New England boggles my imagination.

Please add to my knowledge.

I hope you’re kidding


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[wssix99]

When you shake the load, the arms on the lift will vibrate. This will carry all the way through the lift, through the slab, and into the building and ring the place like a bell. (Assuming everything is bolted down tight.)

To test this, pull the truck out and then drop a 50 lb bag of stone (or whatever) from chest height onto the floor. If you get a "thud" in the door - then you are all good and you are just getting vibrations in the floor translating to the building. (You could also try tamping the floor with something heavy.)

 

[Kaizen]

When you shake the load, the arms on the lift will vibrate. This will carry all the way through the lift, through the slab, and into the building and ring the place like a bell. (Assuming everything is bolted down tight.)

To test this, pull the truck out and then drop a 50 lb bag of stone (or whatever) from chest height onto the floor. If you get a "thud" in the door - then you are all good and you are just getting vibrations in the floor translating to the building. (You could also try tamping the floor with something heavy.)

Thanks this makes sense. Didn’t think about vibration. Mystery solved


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[Bobthetractor]

If it was only happening with the lift motor/pump then I could see a harmonic vibration. Do you have rebar in the floor? I could see that as amplifying things if a lift bolt is touching/close to rebar.

 

[nadogail]

Alaskan Slab in New England?

I am aware that concrete does not always stay where you put it; but for a slab to move from Alaska to New England boggles my imagination.

Please add to my knowledge.

Really I am not kidding, I went to High School in Anchorage, Alaska and this is the first time I have seen the term "Alaskan Slab".

I am requesting knowledge.

 

[PWC Repair]

Thanks this makes sense. Didn’t think about vibration. Mystery solved


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Well sure, a good thunder clap within a few miles shakes my whole shop!

 

[Kaizen]

Really I am not kidding, I went to High School in Anchorage, Alaska and this is the first time I have seen the term "Alaskan Slab".

I am requesting knowledge.

Also called monolithic slab and thickened edge slab. Basically instead of having to dig down past frost line and put a footer and foundation wall it just uses a thick edge with rebar. Not sure why it has Alaskan name. Google it. Tons of info. Saved me over ten grand building mine.


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