WOOD FLOOR VIBRATION 1

[ron9876]

I have a condition where a wood framed floor is spanning 14'-8" between masonry walls. I am considering using No. 2 Southern Pine 2"x12" floor joists at 16" c/c. The ceiling will be drywall and the floor will have 3/4" T&G plywood glued and screwed. Have an area with no walls below or above to help with damping.

Minimal mechanical equipment and hardwood flooring. Is there a procedure for checking vibration. Thanks for any help.

 

[dicksewerrat]

What is your deflection on that?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[RFreund]

I actually just attended a seminar on this and I will try to post the info on Monday. However they suggested deflections tight - around LL/480 and TL/360 (if I recall correctly). Also they said their tests did not find that cross bridging or blocking helped but I can tell you from experience that it will stiffen the floor. They also said that testing done in Canada led to the same conclusion.

EIT

 

[jdgengineer]

For almost all cases we shy away from using sawn lumber for floors. We almost always use TJIs as they are straighter, truer, and less likely to shrink. You may want to consider using engineered lumber, I think it is a far superior product for floors. With that said, iLevel has a floor performance rating for perceived vibration. I think it is based on surveys and not engineering science but we typically use it as an additional serviceability check instead of just using deflection. I too try and limit floor deflections to L/480 and L/360 for wood floors in custom homes.

 

[ToadJones]

ironically, I have a large wide open living area in my house with the exact same construction you described with the sheathing being Advantech brand.
I can jump on the floor and get minimal vibrations, but if my three yr old runs across the floor, she can get into cadence with the floor frequency and the floor wobbles noticeably. I have had adults run across the floor and not noticed it anywhere near as much. My three yr olds weight and impact can set the floor off.

AISC design guide 11 is for floor vibrations and natural frequencies. ?It's possible that the procedures could be adapted to wood.

I dont have anything handy here.

 

[BAretired]

The NBC (Canada) has a procedure for calculating floor vibrations for wood joist floors. It is included in Wood Design Manual 2001 published by the Canadian Wood Council, starting on page 574.

There is also some information on the Internet. Check out this link:

http://www.google.ca/search?q=wood ...fficial&client=firefox-a&source=hp&channel=np

BA

 

[RFreund]

Attached are some of the seminar notes. They do include an equation for vibration as well as a defined range of sensitivity.

EIT
www.HowToEngineer.com

 

[JoshPlumSE]

There was an article in Structural Engineer magazine a few years ago about wood floor vibration. It took me awhile to find it, but here it is:

http://www.gostructural.com/magazin...ing_in_your_step__causing_problems_-5060.html

 

[SLTA]

iLevel has a free program called "Forte" that will help quantify some of the bounciness ideas...

 

[ron9876]

Thanks for the input. Just what I needed.

 

[msquared48]

Just keep the bass below 110 db and you will be fine.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ron9876]

Yep.

 

[FishTheStructure]

@ jdgengineer

TJI's are indeed straighter and create a better, quieter floor. However, in my area if fire fighters know that the floor is made from TJI's they will not go in the building. Just a thought to consider...

Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein

 

[hokie66]

LVL is the norm for floor joists where I am. Big softwood trees are scarce here.

 

[BAretired]

I tend to agree with the firefighters. There is not much meat in a TJI to resist the progress of a fire once it starts. Same goes for light wood trusses made of 2x4's and truss plates. We have had a number of fires in our area over the last year or so and people are starting to question the adequacy of the building code respecting fire protection. I question it too.

BA