Wood Truss Girder Capacity

[ron9876]

I have a question about a girder in a wood truss floor system. Can a 24" deep multiple ply girder span 25.1' and carry 1278 lb/ft?

 

[JAE]

No way to tell without referring to the species of lumber, size of members, connection capacities at joints, etc.

If you can locate the original manufacturer they might be able to get you capacity information.

If not - then probably load testing would be the only way to know.

 

[MiketheEngineer]

That is a reverse engineering solution --- JAE has it right. MUCH more info required...

 

[ron9876]

Sorry. This is a condition that I have on a set of drawings and the truss designer says it won't work.

 

[MiketheEngineer]

Then maybe you should beleive him unless you check it your self

 

[dhengr]

That’s a fairly substantial load for a steel beam, let alone a 24" deep wood truss. The problems will probably be duration of loading, deflection and ganging the several trusses together to actually get them to properly share that loading. Is it a one sided or two sided loading?

 

[ron9876]

It is two sided

 

[msquared48]

How wide is the girder?
I see a maximum shear of 16K and a max moment of 100 Kip feet. That amopunt of moment is a lot for a wood beam, an awful lot. The shear is marginal depending on the width, and we nave not addressed deflection yet.

Right now, with no further information, I would defer to the opinion of the truss designer.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ron9876]

He says it doesn't work with 5 ply.

 

[bpstruct]

Didn't check deflection, but you can get a glulam or powerbeam to work within those dimensions for strength. Not sure if switching to glulam is an option.

 

[msquared48]

5 ply wide? No wonder it won't work!

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ron9876]

Increased depth. Thanks for the input.