Glue Strength

[someengineer]

Hello Engineers,

Does anyone have any information about bond/shear strength of wood construction glues?

 

[Ron]

Adhesives vary a lot. Check with the manufacturer.

 

[Compositepro]

Almost any decent adhesive designed for wood will be stronger than the wood.

 

[hokie66]

Compositepro,

That's a mighty broad statement. Do you mean just for strength across grain? Surely we can't just glue lumber together end to end and depend on the tensile or bending strength to be unreduced.

 

[msquared48]

Tension lams are spliced in Glulams Hokie, but with spline joints. However, as you suggest, I believe that far, far more of the tension force is transferred across the joint by the member above having accumulated the tension thru horizontal shear into it.

These spline joints have been tested in bending though to failure, and the failure usually did not occur at the joint, but in the wood. Perhaps this is what Compositepro was referring to. However, this is still not a butt joint splice, having much greater area and length to develop horizontal shear.

Mike McCann
MMC Engineering

 

[dik]

For wood stuff, I Usually use Bulldog PL Premium adhesive. Will stick steel to wood and wood to wood.

Dik

 

[someengineer]

Thank you for all your comments. I will contact the manufacturer. Some initial research I did, Urethane wood glue had a shear strength of about 4000 psi, pretty strong!

 

[dik]

Urethane wood glues tend to be of the 'foaming' variety, you might want to consider something else.

Dik

 

[Ron]

someengineer...I seem to pick up from your comment that shear strength is very high in urethane adhesives....however, as msquared48 noted, failure in the wood in more critical. If the adhesive is more competent than the parent material that's great....just be sure that you use the lower value (parent material vs. adhesive) for analysis purposes).

 

[dik]

Now you tell me... after I reinforced a bunch of wood joists with steel plate and used the steel strength instead of the wood... back to the drawin' board... I wonder if I can glue steel to steel <G>

Dik

 

[Ron]

dik...my comment only applies when the "steel" is squeezed from a tube!!

 

[someengineer]

Ron,

Thanks for you comments. I have checked the capacity of the wood as it governs.