Structure's sway measurment?

[StrP88]

May I ask what are practical ways/methods to measure displacement/sway of the top of a structure?
Does the type of the structure matter? meaning the method is based on it is a concrete frame structure or steel frame structure?

Any tools/equipment does it for us?

Thank you

 

[MacGruber22]

Really precise laser surveying equipment? What are you trying to do?

-Mac

 

[StrP88]

MacGruber22 (Structural)
Thanks for your response. Can you please tell me more in detail what are the laser surveying equipment? What companies do that? What should I ask them?

I am trying to see how much the top of building sways. The owner is concerned of feeling sway on top of structure
This is not due to wind and structure is an open steel frame structure that is seismically designed but has some vibratory equipment there

 

[WARose]

Pretty much all surveying equipment (at this point) has a "gun" that shoots a laser. You could call a local surveying outfit and explain the situation. I've had survey crews shoot elevations and equipment locations (in buildings) for me before.

Wouldn't it just be simpler to take a look at the structure (i.e. the drawings, calculations, FEA model, etc) to see what the drift should be?

EDIT: If this is a vibration issue.....it might be more feasible to use vibration measurement equipment.

 

[StrP88]

WARose (Structural)
We don't have access to original design calculations and specs.
Drawings don't give the amount of drift? do they?

 

[WARose]

Drawings don't give the amount of drift? do they?

No, but you could look at what code it was done under and see what the seismic drift limit was.

Also, if you got a name (i.e. the company/stamp on the drawings) you could try contacting them and ask for calculations.

You make it sound more like a vibration issue than a drift issue (in your second post). In that case, a survey crew wouldn't be appropriate.....a vibration meter would be best.

 

[StrP88]

WARose (Structural)
Thanks again. Vibration meter- any brands or models you recommend?

Thanks

 

[WARose]

Vibration meter- any brands or models you recommend?

Depends on what frequency it's vibrating at. For 10 Hz or higher, I like my VM-6370 (by M&A Ins.). IIRC, I got it on Amazon pretty cheap. (Less than $300.)

If you have to take measurements less than 10 Hz......it starts getting pretty expensive. The last time I looked into it, we were talking nearly 10k to buy it.....or nearly 2 thousand to rent it.

 

[MotorCity]

I am not up on the latest on greatest survey equipment, but my experience has been that the lasers shoot a stationary target. Is it possible to shoot a moving target and track its path (i.e. a swaying building)?

 

[WARose]

I am not up on the latest on greatest survey equipment, but my experience has been that the lasers shoot a stationary target. Is it possible to shoot a moving target and track its path (i.e. a swaying building)?

I would think so. After all, the rod cannot be held perfectly still by anyone. (Nobody has hands that steady.)

The hard part would be getting the gun lined up fast enough (on the reflector) during the motion.

 

[XR250]

There's an app for that...

https://itunes.apple.com/us/app/vibsensor/id932854520?ls=1&mt=8

Who knows if it has sufficient accuracy