Correct terminology for a doubler on the bottom of a wood beam 2

[DPAJR]

A few months back I came across a thread that discussed adding a doubler to the bottom of a wood beam that was undersized. The thread used a term for the doubler that I had never heard before so I bookmarked it somewhere. Wish I knew where. I also came across it in a book. Can't find that either.

It's tough getting old especially if you were already stupid.

Anyone out there know the correct term?

Thanks
dpa

 

[Lion06]

I've heard of using a "strongback".

 

[nutte]

Flitch plate?

 

[DPAJR]

Flitch Plate. Thank you thank you thank you. I never would have dredged that out of the back of my brain in a million years.

Dear EIT,

I have heard the term strongback used when a beam like arrangement is used to support a long heavy item at more than one point. It is used with heavy cranes when lifting pipe or long beams. It may apply to structures I'm not sure. I will search the sites for both terms.

Thanks guys

 

[DPAJR]

Dear EIT,

You are right strongback is also a structural term in addition to being a crane rigging term. Turns out a flitch plate is vertical and sandwitched between two wood beams and a strong back is on top (maybe also bottom?) of a beam.

Turns out strongback is what I am trying to do here since the structure is not accessible for adding a flitch plate.

Thanks again

 

[hokie66]

Scab?

 

[msquared48]

A "Sister" is added to the side, not below.

Mike McCann
MMC Engineering

 

[msquared48]

Composite?

Mike McCann
MMC Engineering

 

[msquared48]

Laminated...

Mike McCann
MMC Engineering

 

[ChipB]

Flitchplate design:
Download at:

http://www.toolbase.org/ToolbaseRes...ContentDetailID=2809&BucketID=4&CategoryID=35

 

[hokie66]

I think Mike is correct, a lump of timber added to the bottom of a timber beam would be a laminate. For it to be effective in resisting moment, the horizontal shear has to be developed. One simple way of doing this is to provide enough shear connection on each half of the beam to develop the strength of the laminate in tension.

 

[MaddEngineer]

I don't know if strongback is the best term, actually I think it is more of a sailing (nautical) term, hence its use in rigging terminology.

I think it all depends on what the member is and how are you utilizing it.

If it is a timber/steel beam placed below the existing beam you could call it a bolster beam, or a relieving beam.

If it is a timber or steel member fastened/bonded compositly to the bottom of the wood beam you could call it a strengthener or reinforcing plate.

 

[MikeHalloran]

In wooden aircraft spars or ribs, I think it's called a 'cap' or 'cap strip', whether on top or bottom.

I could swear I've heard 'cap' used to describe a half- length doubler welded to the bottom of a steel beam to stiffen it, but it's been a long time.



Mike Halloran
Pembroke Pines, FL, USA

 

[apsix]

"Strongbacks are used to reinforce critical areas of panels during erection."
(

http://universalbuildingproducts.net/library/1996/ds_strongback_bolt.pdf)

Eg. for panels riddled with holes which aren't able to support their own weight when not vertical.