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Nail end edge/end distance for end of beam connection

Nail end edge/end distance for end of beam connection

(OP)
I have an existing 5 1/8" wide roof glue-laminated beam. I need to connect a 2x8 joist to the end of the glue-laminated beam (cantilever end of the beam). I am using the joist hanger from the Simpson (MUS28). My concern is that the nails are very close to the edge of the glue-laminated beam (end section of the beam as shown in the attached sketch). The NDS has requirements regarding the end/edge distance for the bolts. Is there any requirements for the end/edge distance of nails connected to the end of a beam of this nature? Any other detail I can use to resolve this issue?http://res.cloudinary.com/engineering-com/image/upload/v1453073810/tips/CCF01172016_dmgyrz.pdf

RE: Nail end edge/end distance for end of beam connection

The nails are installed into END GRAIN. In this case, I think I would be concerned about any nails near the top of the glu-lam. My recollection is that the edge distance limits on nails are somewhat vague in that they only stipulate "so as to not cause splitting" or something to that effect. (I might be mistaken about that but I thought there is something like that in NDS.) Seems like nails near the top would be prone to splitting out of the top.

Regardless, it seems to me that the real concern would be END GRAIN WITHDRAWAL. If there is any reliance on withdrawal involved in the connection, it is not allowed by NDS for nails in end grain.

Lateral load values for nails in end grain should be about 2/3 of the values for side grain parallel to the grain.

RE: Nail end edge/end distance for end of beam connection

I don't think the OP meant into the end grain, but Normal to the beam at the end. He needs to clarify that though.

If these hangers are placed with any flanges turned in and placed at the end of the beam, they should still be ok. Done all the time.

Mike McCann, PE, SE (WA)


RE: Nail end edge/end distance for end of beam connection

MS - Looking at the sketch, it sure looks like an end grain connection to me.

Also, what is meant by "at the encouragement of the beam" ? I'm not familiar with that term.

RE: Nail end edge/end distance for end of beam connection

And you are correct on the end of the beam.

Mike McCann, PE, SE (WA)


RE: Nail end edge/end distance for end of beam connection

(OP)
The hanger supports only vertical gravity load from the roof. No lateral load and nails are not subject to withdrawal, since the hanger is not part of the lateral load resisting system of the building.

RE: Nail end edge/end distance for end of beam connection

You need to move the joist to align with one side of the glulam beam and then screw it from side (at 90° angle).
Or make a custom steel hanger that wraps around glulam beam and again screw it from side.

Structural timber engineering

RE: Nail end edge/end distance for end of beam connection

I can see that moving the 2x8 to be flush with the side is one way to do this but I'm not sure that it would be better than attachment at the end of the GL and I definitely don't see why he "needs" to do that. Also seems like the alignment o the two ridges might be a "trick".

Since the new beam is a single 2x8, I would surmise that the load is relatively light.
End nails do have design values so that still seems viable.

With a side lapped connector, it seems to me that there would be a need for a much larger connector. A standard metal hanger with concealed flanges is readily available for the single ridge board so it is a matter of checking the capacity with the design load.

RE: Nail end edge/end distance for end of beam connection

At least put a steel strap with nails on top to connect new and existing beam.

If there are end grain cracks in the glulam, then shear design value per nail is just theory. In reality you'll just have a 'weak' link.

Structural timber engineering

RE: Nail end edge/end distance for end of beam connection

If it's a connection not exposed to view, you could always just screw an upright 2x6 board to the end of the glulam below the joist for good measure. There's something to be said for direct bearing.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Nail end edge/end distance for end of beam connection

I would be more prone to use the design of Simpson Strong Tie HU26TF hanger.
I am also of the opinion that manufacturers of glue laminated beams (or their related association) have engineering details about nail and screw connections into the ends of such beams, after all there is abundant data for such connections on regular wood .

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