Powder Actuated Fasteners to Steel in High Seismic

[sticksandtriangles]

Hoping to get some clarity on the use of PAF's in high seismic applications to steel.

ASCE 7-16 13.4.5 has this line:

PAFs in conc or steel shall not be used for sustained tension loads or brace applications in SDC D,E, or F unless approved for seismic loading (I know of no PAF approved for seismic loading).
Exception 2. PAFs in steel where the service load on any 1 fastener does not exceed 250 lbs.

Does exception (2) override all items noted in the first paragraph, aka, I can use PAF's for sustained tension/bracing applications so long as the load is limited to 250lbs?

This structure magazine article has a portion titled "Clarifying the seismic grey zone" and yet I am still confused

https://www.structuremag.org/?p=921

Thanks

S&T -

http://www.re-tug.com

 

[sandman21]

"For interior, nonstructural walls that are not subject to sustained tension loads and are not a bracing application, power-driven fasteners may be used to attach steel track to concrete or steel in all Seismic Design Categories. In Seismic Design Categories D, E, and F, the allowable shear load due to transverse pressure shall be no more than 90 pounds when attaching to concrete; or 250 pounds when attaching to steel. "

When a shotpin goes to concrete the maximum allowable load is 90#, exception 2 raise that to 250# for applications to steel. It does not allow shot pins for sustained loads unless it has approval for seismic loading.

 

[RipPECity]

The way I've read it is that in steel & SDC D or up, if you are less than 250lbs per PAF, you can use it in a sustained tension or brace application. The exception overrides the above statement. Right?

 

[sticksandtriangles]

The way ASCE 7 is written, it feels like you would be allowed to use PAFs in sustained tension/brace applications given the exception, but the structure magazine article seems to have differing verbiage.

It is also hard for me to wrap my head around the example referenced in the magazine article, wouldn't the top track/bottom track anchorage for an interior nonstructural wall be a "bracing application"?

 

[skeletron]

I've had pushback on this issue before and the AHJ or EOR does not accept the 90lb limit. It's just so much less headache to spec a KH-EZ or Titen HD. In my case, I had a partial height non-loadbearing steel stud wall with a stud brace @ 45deg to the concrete. The detail had 3 x PAF to connect the brace to the u/s of slab. Our solution was to just have the contractor go in and put a screw anchor in addition to the PAF.

Where I practice there is a special bulletin from the AHJ and the Building Board that restricts the use of PAF and drop-in anchors in "seismic tension". Oddly enough, there is a fair bit of Post-Tensioned slabs in the area as well...so finding a shallow anchor can be challenging.

I'm just realizing now that your question is in regards to steel. My understanding was that PAF actually have been shown to perform well in steel...if I can dig up some research I'll provide that later.

 

[RipPECity]

@sticksandtriangles

I agree - to me I think the code is pretty clear.

@skeletron

I have never gotten pushback from a reviewer...but I do get pushback all the time from contractors not understanding that I can't make a seismic splay attach to concrete with a PAF. Apparently their last engineer made it work just fine...

 

[skeletron]

@RipPECity:
Oh for sure! A splay wire brace with a PAF can't be done. I've seen it happen on a big TI. The Contractor had to rip most everything out.