Point load applied to roof diaphram

[UnneutralAxis]

A building I'm working on has had some changes per the architect. I now have a point load from a newly added wind girt that was never anticipated. I've looked and looked for a way to resist the girt's reaction of 4500 lbs from wind loading. Not that big, but something has to do it.

Load is applied at roof level. 3/4" plywood diaphragm. Would you feel comfortable just using a long piece of glulam blocking with a couple rows of 16d nails through the plywood into the top of the blocking to resist the load? I have up to 10' available for the length of the blocking. I have mono trusses framing perpendicular to the blocking... trusses are parallel to girt.

Any better ideas?

 

[UnneutralAxis]

Since we are in an engineering forum here... it's actually hydrogen that is combustible, not helium.

Thanks for the lesson on balloon framing though, Mike.

 

[ToadJones]

Mike-
you poking fun at my terminology?

 

[a2mfk]

Ohhhhhhhh the humanity!!!!!!!

 

[msquared48]

Toad:

Even though I use the same terms, I have fun wherever I can. After 40 years of this stuff, I need it. Thanks for the opportunity.

By the way, just checkin that you guys were reading my posts with the helium comment, OK? (just kidding)

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[ToadJones]

Mike-
No offense taken...I have been accused being a smart a$$ here and there too.

 

[msquared48]

No worries mate.


Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[a2mfk]

Helium, hydrogen, they both are lighter than air, but hydrogen is more abundant. Lets just use that to fill our dirigibles, what could go wr.....

 

[UnneutralAxis]

Following up here. What is the largest point load you guys would feel comfortable putting in a wood diaphragm? I know it depends on the exact situation and a thousand other factors. I've thought about this quite a bit the last couple days. There's really no really good way to theoretically arrive at it... more a judgment call than anything else. I have some thoughts on the matter, but wanted to hear others'.

 

[a2mfk]

The limits are your diaphragm, the drag strut length and member design, and making the connection from the girt to the drag strut. Most pre-fab steel connections for timber are not designed for this, but may be able to be used for that application. You can always design your own steel buckets/plates, I have done that several times. With wood, I try to avoid this type of detail.

Also, if you are balloon framing the end wall, remember anchorage for suction on that wall. You may have to use some tension straps at the top of the framing to get the load into the roof...