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RE: Soils Reports under CBC 1802.2

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Unfortunately, there's not much of a loop hole there.  The exception to
1802.2.7, item 2 only applies to the site-specific study for peak ground
acceleration taking into account soil amplification effects.

All of the other soils report requirements dictated in Section 1802.6
still have to be addressed, and in SDCs D, E, and F, so do the rest of
the items contained in 1802.2.7, items 1 and 2.

All projects in our jurisdiction are assigned to SDC E or F, and we are
really struggling with the fact that we're forced to require soils
reports for even small projects on infill lots.


Brian Gerving
Plans Examiner
City of Eureka Building Department

-----Original Message-----
From: Thor Matteson [mailto:thor(--nospam--at)yosemite.net] 
Sent: Thursday, February 14, 2008 6:28 AM
To: SEAINT
Subject: Soils Reports under CBC 1802.2

I keep hoping to find a loop-hole....

Section 1802.2.7, item 2, Exception states:  "A site-specific study need
not
be performed, provided that peak ground acceleration equal to
(S-sub-DS)/2.5
is used, where S-sub-DS is determined in accordance with Section 21.2.1
of
ASCE-7"

The above exception *looks* like it's intended to let you "over-design"
(GOD, I hate that term...) for seismic and avoid having a site-specific
soils report.  BUT--  when you go to Section 21.2.1 of ASCE-7, there is
no
mention of S-sub-DS.  In fact S-sub-DS is barely mentioned in Chapter 21
at
all.   Chapter 21 deals with site-specific accelerations anyway, so this
is
sort of a circular argument ("you don't need a site-specific soils
survey if
you have done a site-specific soils survey").

Could it be that the reference to Section 21.2.1 is incorrect?  If so,
which
section should be referenced instead?

Thanks for any hints....

Our office is hoping that reports from the Natural Resources
Conservation
Service (NRCS, part of the US Dept of Agriculture) website will be
acceptable for 'run-of-the-mill' projects.  They give the USCS soil
types of
SM, GP, SW, etc. that can then be cross-referenced with IBC/CBC Table
1804.2
for soil bearing values.

The NRCS "Web Soil Survey" site is:
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx
You might have to go to this site first to load the application:
http://websoilsurvey.nrcs.usda.gov/app/
I have not spent too much time there, but it has an *amazing* amount of
info.  We all paid for it---can we at least USE it now, please??

Thor Matteson
www.shearwalls.com


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