Mark,
Can you give me some background on where you've come to this conclusion
on seismic design category D and higher not being
within the scope of NFPA-13? My latest ASCE7 manual seems to suggest
otherwise.
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website
Eckard, Mark - Mark E wrote:
Another issue with seismic bracing design and calculation is the fact
that NFPA 13 only applies to seismic design category A, B, & C.
Categories "A" and "B" usually do not require bracing unless it is a
local jurisdictional requirement to brace everything. Seismic design
category D and higher are out of the scope of NFPA-13 and require design
by a Professional Engineer. So in summary NFPA is good for Seismic
design category "C".
I have come to realize that quite a large number of designers don't
realize this.
Mark E. Eckard S.E.T.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Steve
Leyton
Sent: Wednesday, May 28, 2008 11:33 AM
To: sprinklerforum@firesprinkler.org
Subject: RE: Seismic Calcs
If you consider this issue in terms of the 2007 standard, the sprinkler
system EQB designs are based on standard values that can be taken from
referenced sources (such as ASCE). You then plug the values into
equations prescribed by NFPA 13 and you get a finalized design
(basically, you confirm the fastener or means of anchorage for the brace
assembly). None of which takes into account the capacity of the
building itself to bear the applied loads that have been calculated, but
you don't need the help of an SE to simply design the braces.
Once upon a time, we did our designs on a deferred basis, showed EQB's
every 40', picked a hanger based on the type of structural member and
submitted for approval. Today, especially here in the Southwest, we
consult the project structural engineer of record on every project.
Modern lightweight construction systems, engineered wood products and
high seismic force values often mean that even if one could design a
brace assembly that bears enough load to space out to 40' on center, you
simply can't put 600, or 700 or 800 lbs. of horizontal load on the floor
or roof framing. We currently have projects where bracing is limited to
25-30' on center, just to dilute the load on each brace.
Southern California has several fire departments that now REQUIRE review
by the SE of record and an accompanying letter of acceptance. This
speaks to the original question of what to put on the shop drawings -
perhaps nothing, if you can submit documentation of a 3rd-party review.
I know that this is another step that most in our industry have never
undertaken and generally doesn't account for in estimating design costs,
but I strongly recommend that every project be submitted to the
Architect for review by the designer(s) of record before submittal to
the FD. And if you're in a region that is just now breaking into the
whole "seismic thing", I would also craft language into my standard
proposal form that excludes costs for review by structural engineer as
may be required.
Steve Leyton
Protection Design & Consulting
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Todd
Williams - FPDC
Sent: Wednesday, May 28, 2008 7:51 AM
To: sprinklerforum@firesprinkler.org
Subject: Re: Seismic Calcs
Bill,
I think that you may have discovered another disconnect between
theory and practice. To my knowledge, none of the AHJs in my area
have either the expertise or staff to do a review on seismic. My
guess is that they are just going to say "yes, there is seismic".
That is pretty much what I see now and I don't see it changing, given
municipal budgeting. The exception could possibly be in larger cities
or at the state level. The structural engineer from the design team
(assuming that there is one) would be the only person qualified to do
an actual review. Whether they ever see sprinkler shop drawings is
questionable.
At 10:02 AM 5/28/2008, you wrote:
NFPA 13-2007, 22.1.3(39) requires "Calculation of loads for sizing and
details of sway bracing". What should a typical shop drawing package
include so that the selected sway bracing can be approved?
Who reviews these calculations prior to submission to the AHJ? Do AHJs
pass these on to structural design reviewers, or are the sprinkler
installer's submittals accepted without review?
Bill Brooks
William N. Brooks, P.E.
Brooks Fire Protection Engineering Inc.
372 Wilett Drive
Severna Park, MD 21146
410-544-3620 Phone
410-544-3032 FAX
412-400-6528 Cell
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Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
www.fpdc.com
860.535.2080
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