Bearing strength of particleboard 1

[ajk1]

I am checking the bearing strength of particleboard, where the common small diameter pins used to support the adjustable shelves fit into the holes in the supporting paticleboard vertical member. Does anyone know what particleboard used in shelving can safely support in that type of bearing? A preliminary approximate calculation indicates a peak bearing stress under the pin of about 900 psi, where the particleboard bearing has failed.

 

[structSU10]

found these on google:

http://ucanr.edu/sites/woodybiomass/newsletters/fpl_wood_handbook33291.pdf

reference American national standard for particle board

http://www.flakeboard.com/specs/ANSI A208.1-1999 PB.pdf

where some of the reference values came from:

http://babel.hathitrust.org/cgi/pt?id=umn.31951d02889735n;view=1up;seq=9

 

[CANPRO]

whats your application? I would be hesitant to rely on that for anything remotely important. Even with references in hand I would not rely on that stuff. I have to ask, why are you engineering a book shelf?

 

[ajk1]

It was not engineered and it collapsed. I have found in my lifetime that engineering principles can be applied to many things, and a lot of expense and trouble would have been avoided had these items been engineered. We could solve he issue by engineering, or we could do it by trial and error. I prfere the engineered approach. We trusted an experienced book shelf manufacturer, and it fell down.

Thanks for the references. I will study up on them. Much apreciated.

 

[XR250]

Wouldn't an experienced bookshelf maker use plywood instead of particleboard?
Sounds like Walmart

 

[racookpe1978]

I hope no one was hurt by the falling shelf and contents, and the damage to the room and (former) shelf contents was minimal.

 

[Ron]

ajk1...engineering is not always readily calculable....in such cases, a proof load (also an engineering process) works better.

 

[ajk1]

Ron - yes proof load testing occurred to me but in general I much prefer to calculate the capacity. But if I cannot find the allowable compressive bearing strength of the material, then proof load testing would be necessary.

 

[ajk1]

Another thought - if it is load tested and it passes, fine, but if it fails, it still won't be known what size connecting pin should be used. If it is calculated, it then can be calculated what size supporting pin can be used.

No books fell off the shelf - it was noticed that one corner of the shelf was lower.

I will have to check whether the material is plywood or fibreboard. I think that the fundamental problem was that there was a gap between the end of the plywood shelf and the supporting vertical member into which the pin fit. Such a large gap is not present at other shelves in the units. I don't know yet if the gap is there because the shelf was cut too short, or because the supporting vertical member bowed due to relative humidity changes from summer to winter, which varies from 15% in winter to 65% in summer.

 

[CANPRO]

I think that particle board is too inconsistent to rely on tests or calculations. Its just crap. I'm not trying to take away from anything you're trying to do here, I just think if you're putting something on a shelf and you feel it is important enough that you want to confirm the strength of the shelf, then you should not be using particle board to support it. I have a few of these in my house right now because they are cheap, and they all look like they're ready to collapse because they are full of books. When I have the time, I'm just going to buy a few sheets of plywood and build my own.

Regarding the pin...if you don't need to adjust the height of the shelves then you can screw in a long piece of wood below the shelf and give it continuous support.

 

[manstrom]

Threads like this are why my wife makes fun of me.

 

[ztengguy]

I had that happen to me, one of my pins failed the wood, and the corner sloped down a bit. luckily there were a few books under that shelf and they supported the shelf and disaster was avoided. Otherwise, I could have had a smushed doggie, he likes to sleep below the book shelf.

If you find that its not engineered right, I would see if a class action lawsuit could be started, I hate to bring lawyers into the mix, but think if it was a kid playing at the base of the bookshelf, and not a pooch.

 

[EngineeringEric]

That gap would definitely make matters worse. you would be getting prying action and localized tension/compression in the actual shelf board. My experience with shelves is that they are not meant to carry much load unless explicitly designed to. Looking around my office i see 5-6 shelves with at least 3/8" sag over 3feet. I would consider that a failure, not catastrophic yet.

 

[msquared48]

"A preliminary approximate calculation indicates a peak bearing stress under the pin of about 900 psi, where the particleboard bearing has failed."

So design the connection for 250 psi and call it good.

Mike McCann, PE, SE (WA)

 

[Tomfh]

The pins work in combined shear/bending/bearing, plus the material is nonhomogeneous and anisotropic (woodchips/glue/laminate/etc). It's hard to calculate.

Pins and particleboard are cheap and you can bust plenty of them in a short time using household equipment.

I would think testing is the way to go here.