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Wood and metal join tecnique

Wood and metal join tecnique

Wood and metal join tecnique

Which is the strongest way to join a Wood beam and a Metal frame?

And Which is the strongest way to join a Wood beam and a Metal Beam?

In the link below I have shown two ways representing both cases.

In figure 1, A wood beam is joined with Metal beam in a way. Which is the strongest joint technique?

In figure 1 and 2, A wood beam is joined with metal frame. First one is indirectly welded. 2nd one is directly screwed.

RE: Wood and metal join tecnique

A hanger is the best. As for your details both will work. I would use a knife plate (your detail 1) only for a hidden connection. The angle plate, I would use an angle each side of the wood beam.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: Wood and metal join tecnique

Thanks. Ill go for knife plate then. smile

RE: Wood and metal join tecnique

If the joint is to be loaded only on one direction - like gravity loading, a connection using bearing is the best. You can add a plate to the bottom of the knife plate to bear on the bottom of the beam.

One needs to be careful using connections hanging from bolts or pins. This type of connection can cause cross-grain tension - the weakest and most unpredictable way to load wood. Similar to a wedge used in splitting fire wood.
The wood can split along the line of the fasteners.

RE: Wood and metal join tecnique

The main flaw with detail 1 is that there is a good chance for the wood beam to develop an horizontal crack thru the bolt hole where the horizontal shear stress is the highest. While detail 2 would appear unsightly, nonetheless, that would be my preference but as mentioned above with two clips instead of one. It all depends on the loading for a selection between details 1 and 2.

RE: Wood and metal join tecnique

Joist hangers such as the Simpson strong ties may be another option

RE: Wood and metal join tecnique

As others have said, I believe both solutions are problematic as you are relying on a very small area presented to the wood by the top of each screw or bolt.

The chance of the wood splitting and failing catastrophically is too great.

You really need some steel UNDER the wood. The Screws/Bolts should not support the wood, just keep it in place.

As displayed in the drawings, any wood UNDER the Fasteners is dead weight, and is not contributing any strength to the joint at all. Yes, the wood under the fasteners does make a difference at all places other than the joint. But when the joint fails, nothing else will matter.

That said, Drawing #2 is slightly better (though still problematic). Keep in mind you never want to add additional cuts and holes to any piece wood that are unnecessary, and Drawing #1 does just that.

RE: Wood and metal join tecnique

If you must use Drawing #1 or #2, drill only the two LOWER HOLES into the wood, and for #2 use an L-Bracket on both sides so as to minimize the TWISTING that Drawing #2 introduces.

Honestly, both Drawings concern me a lot if you're using Sawn Lumber.

RE: Wood and metal join tecnique

Keep in mind that as time passes, if your wooden elements keep dry, they will shrink and your initially tight connections will be loose. This will exacerbate the situation.

With a lip of Steel Welded underneath the Wooden Beam, you'd be so much better off.

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