Installing force plates on the third floor?

[Ryan Chang]

Hi,

we are in the process of moving a lab. The new lab will be on the third floor (not ideal for a force plate). The floors are 14 inch thick concrete. At every 20 feet (on every floor in the both the length and width direction), there are concrete pillars with approximate a 3 foot diameter (see pic) .

I was wondering if anyone could share advice on installation of force plates at higher floors. Are there different installation techniques? How good/bad has been your data? Advice on smoothing?

Our lab will also have other sources of impact and vibrations, such as treadmills in the vicinity.

Thanks,
Ryan

[Edmund Cramp]

Re: Installing force plates on the third floor?

I'm not seeing a picture on your post but, while a third floor location is not ideal, there are many labs around the world with force places in these locations that are getting good data. Overall I've seen more problems from bad mounting than external vibration so just do a good job of mounting the force plate and you should be OK.

If you have other devices with moving parts/motion around then these are potential sources of noise - you may need to look at their mountings to try and reduce impulse noise - for example, a treadmill will not generate much physical vibration by itself but once a line-backer jumps on and starts running, then mounting issues could result in the treadmill "tapping" the floor which you will probably detect. You may need to stop using these devices while you collect data.

[Dan India]

Re: Installing force plates on the third floor?

Hello Ryan:

I have installed force plates in Downtown Chicago on 14th floor Labs and and in NYC on similar structured. The biggest issue is insuring that you have sufficient support under the force plate. Cutting into the concrete on a raised floor of a new building may leave you with a few inches and civil engineers will frown upon that idea. Hence most upper floor structures are mounted on the actual floor (to concrete) and then a raise flooring system is provided around the plates.

To test your flooring stability, you can call civil engineers that do such testing. Or you can place a few glasses of water around the area to mount and start jumping / running past that point and via a camera looking into the glass you hope not to find ripples.

Dan India
Qualisys Motion Systems

[Ryan Chang]

Re: Installing force plates on the third floor?

Thank you both for your input. The glass of water is a great idea - I've been wondering what I could use as a quick test.

Edmund, sorry the pic did not work the first time. Here it is:

drydock pic.jpg

[Edmund Cramp]

Re: Installing force plates on the third floor?

Never, ever, cut into a concrete floor in a building without a long discussion with the building engineers and architects. A raise floor, or runway, around the plate is the only way to go.

I have seen force plate pits in multistory buildings but these were either designed into the building originally, or constructed at great expense and considerable engineering work afterwards.

[Edmund Cramp]

Re: Installing force plates on the third floor?

That looks pretty solid - I would think you would be OK. Assuming that you get the go-ahead to do this and it works, it would be very useful if you could post an update at some point in the future to provide a little positive feedback for others facing the same situation.

[Manvendra Singh]

Re: Installing force plates on the third floor?

Key is, to always mount Force Plates on solid base of RCC slab, never on floor finish above it. And, never cut into the RCC slab, because that would endanger the structural safety of the building.

[Edmund Cramp]

Re: Installing force plates on the third floor?

Key is, to always mount Force Plates on solid base of RCC slab, never on floor finish above it. And, never cut into the RCC slab, because that would endanger the structural safety of the building.

Absolutely - this is very important. For those of you who do not have a architectural background, RCC is Reinforced Cement Concrete, that is the concrete floor of the building. Cutting or drilling into the building floor can weaken the building. It's generally not a problem to remove floor surfaces with the building owners permission and it should not be a problem to rough up the RCC surface to ensure that the force plate mounting plate can be firmly glued to the building.

It is important when mounting a force plate, that the mounting plate, which the force plate is attached to, does not move at all and that the force plate is attached to the mounting plate firmly without any possibility of movement. In addition, make sure that any surrounding walkway, or raised floor components, do not touch either the force plate (obviously) or the mounting plate (not so obvious). It is easy to get pre-foot strike noise in your data if the surrounding floor or walkway has any possibility of motion - this will cause a tapping on the floor, which travels to the mounting plate and then into the force plate sensors - and eventually, your data.