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Alternate BWP's (Thor & Dennis)

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Thor & Dennis,

I'm not sure if someone pointed this out yet (I'm a little too quick
with the "delete" button), but UBC Section 2320.11.4 DOES require a
continuous, reinforced foundation along the entire wall line that
contains an "alternate braced wall panel". I'm not familiar with the
IRC, but this requirement was included and expanded in Section
2308.9.3.1 of the 2000 IBC.


FYI,
Dave Adams, S.E.
Lane Engineers, Inc.
Tulare, CA
davea(--nospam--at)laneengineers.com




-----Original Message-----
From: Dennis Wish [mailto:dennis.wish(--nospam--at)verizon.net]
Sent: Sunday, October 26, 2003 3:07 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Thickened footings under interior braced walls (Was: RE
Hardy Frames)


Thor, I agree with you on this one. Although, section 1806.6 has been
revised and it appears that there are no responsible building officials
in my area :>) - probably the reason I stay away from Conventional
construction.

To answer Aleces question; The Conventional Construction section is not
governed by engineers. ICBO consisted of other lobbyists which include
the National Association of Home Builders and the Building Industry
Association. The NAHB has been working with the AF&PA as well as
research done by Georgia Tech to develop studies that might be published
to satisfy HUD standards for low income housing. Given the opportunity,
NAHB and BIA would rather engineers be out of the housing industry.
However, there is a catch-22;

Homes that are originally designed as low income become a product of
their property values. The best investment has always been real-estate
and the price of low income housing usually grows to a point where low
income families can financially benefit from the profit earned on their
homes - thus moving up in the world. The home then becomes available at
whatever the market will bear and there is no disclosure required as to
the method used to design and build the home. A permit was issued and
"Buyer Beware". 

Low income tract homes represent some of the most expensive real-estate
in California. The city of Indian Wells is considered one of the most
expensive places to live, yet the quality of the homes sold at
$1,000,000.00 plus is simply that of a low income tract home constructed
in the fifties through the seventies - when Indian Wells was not
popular. So the homebuyers who now own these expensive homes find that
at 15% deductible for state seismic coverage, they must layout up to
$150,000.00 out of pocket to reconstruct their home when damage occurs
after a seismic event.

True, the value of the property is more than the value of the home that
sits on it, but the value is based on what the county evaluates the land
cost to be and the value of the structure above. In most cases, the cost
of the home is still much more than the percentage paid out-of-pocket by
the new buyer can bear.

Forget for the moment that we are talking about people who may be able
to afford to repair their homes. Now consider the low income family that
still owns that home that has appreciated in value. They work multiple
jobs in order to get ahead, but if I am correct, their income does not
increase as it had years ago. Still, the cost of homes in my
neighborhood (which includes low income homes) has more than doubled in
three years. The families who own the low income homes face a much
higher cost of replacement if they have appropriate coverage from their
insurance carrier. The cost of labor and materials has increased, maybe
not as much as the cost of land, but inflation has still accelerated the
cost to replace these homes. Quite frankly, the low income family will
not be able to cover their cost to rebuild a Conventionally framed home
that, while protecting lives, will suffer a good deal of damage as they
had in Northridge (Check the NAHB report that admits most homes
constructed in the San Fernando Valley were constructed to prescriptive
methods). 

So, why can't we upgrade this section of the code or the forthcoming
IRC. As a former member of the BSSC TS-7 committee, one thing I learned
is that the snowball is rolling downhill and there is nothing that I as
a member can do other than write a note of dissent. There are no
discussions between members (I tried and got shot down by the committee
chair) and all that is expected is for the member to find errors in
rhetoric on an already ready to be published code.

Do I sound bitter - sure. The lobby of the NAHB and BIA has obvious
clout and political power. This section of the code represents their
authority and SEA, in my opinion, does not choose to use the financial
resources that they have to fight it. Years ago it was evident that
prescriptive methods must not be less than the minimum engineered value
- it no longer is the case and conventional construction is expanding to
multi-story larger buildings as long as they remove any irregularity.
With our codes getting more complex, it is obvious that we create
incentives in high risk areas for those who are willing to build a box
using conventional means.

If I live long enough, I may have a great future in seismic repair of
light-framed buildings constructed by prescriptive methods. With only 8
or 10 local engineers for over 150,000 people, the future markets look
bright. Add to this that the San Andreas is 50 years beyond a major
event, I might make a few bucks before I retire!

"I should live so long :>)"

Dennis

-----Original Message-----
From: Thor Matteson, SE [mailto:matteson(--nospam--at)yosemite.net] 
Sent: Sunday, October 26, 2003 6:50 AM
To: SEAINT
Subject: Re: Thickened footings under interior braced walls (Was: RE
Hardy Frames)

Two points to make:

First, in response to Antonio,  the Code People (in particular, John
Henry
of the ICBO/ICC) make a distinction between BRACED walls and SHEAR
walls.
Braced walls occur in Conventional Light-frame construction, and include
let-in braces and gypsum sheathing (shudder).   The conventional framing
section of the code does not mention Shear Walls.  So while any engineer
knows that OF COURSE you need a foundation under a Shear Wall, the code
does
not require them under Braced Walls.

Which brings up point #2:  Section 2320.11.3 requires that "sills shall
be
bolted to the foundation or slab in accordance with Section 1806.6".  It
does not say what thicknes the slab should be.  Section 1806.6 requires
7-inch bolt embedment into concrete (not a combination of concrete and
dirt...)   If you have an "alternate braced wall panel" that requires
tie-downs with the 1800 or 3000 pound capacities, you are not going to
get
the manufacturer's rated uplift capacities by embedding an anchor rod
for
the tie-down into a 3-1/2 inch slab.

I don't see any way that a reasonably responsible building official
could
allow installing a braced wall panel on a slab (or thickened part of the
slab) less than 10 inches thick.   Note the qualifier used before
"building
official".

As for the Conventional Framing section of the code and the IRC, I think
they have their place--but we are seeing huge abuses of them where
designers
are pushing the envelope in every direction possible, all at the same
time.

Thor Matteson, SE

www.shearwalls.com




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