Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Wood Moment Frame?

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I couldn't agree with you more. SEAOSC published a document - their plan
called Vision 2000. At the time, Vision 2000 was considered a plan to
revise building codes to be performance based. I interpreted this to
mean that the person with the checkbook could decide how much protection
he was willing to invest in.
This was a dangerous scheme. If you go back through many of the SEAINT
archives, you will find that I attacked Vision 2000 since before the
codification of 97 UBC. 
I was told at the last SEAOC convention held in Santa Barbara (was that
1999 or 2000) that SEAOC had no intentions of trying to promote a code
that attempted to predict the performance of a building and then what
they published did exactly that. However, the published code simply took
away the choice and increased performance expectations while increasing
design complexity. 
It seems strange to me that in 2001 we are still using the 1997 UBC
(have not adopted the 2000 IBC) and still do not have an appropriate
tool on the market that is commercially available to design in
full-compliance with the intent of the code (notice that I use Intent of
code as an oxymoron). 
On the other end of the field is the one section of the code for Type V
that acts to negate all of the intentions of the code write - a small
prescriptive section (2320) called Conventional Construction. 

I hear groaning in the background (here he goes again!). The sad fact is
that there is a dividing line between these two sections of the code
(full-compliance and conventional prescriptive construction) acting like
a wide parkway between two roads running in opposite directions. One
wants builders stiffer and more predictable but doesn't really
understand the nature of the materials. The other side wants less
material, less controls and is finding that their understanding of
performance needs a little bid of strengthening in regions of high risk.

No matter how hard many of us have tried to make these issues public,
there are enough voices to dilute the issues so that each side continues
to work independent and offers no hope of compromise. 

I will admit that I personally am leaning at the more liberal side on
this argument as those who promoted conventional construction are doing
more in the form of research and development to test the performance of
cost effective methods such as perforated shearwalls, proprietary shear
elements, and much more. On the other side is our Seismology Committee
who has yet to address with conviction, the issues that we have been
questioning for the last two or three years. The answers are always the
same - there is nothing anyone can do to change a code that has no
future, and if you have a problem with it you should be involved and try
to change it (a Catch-22). 

What I do see emerging is an effective prescriptive method in the form
of the next IRC. This looks pretty good as long as you don't use it in
the high risk zones. 

If you want to jump into this discussion without offending SEA on their
own list, you can access the thread at:
(this link should all be on one line starting with http: and ending with

Dennis S. Wish, PE
California Professional Engineer
Administrator - The Structuralist.Net
Professional Forum:
Public Forum on Housing:
Our older "UltraBoard" discussion forum will remain operational for the
next 30 to 60 days until all information has been sucessfully transfered
to our new board listed above.
If you are a registered member of the old forum, please logon to our new
forum noted above and re-register. You may use the same name and
You may continue to use the old board until all information has been
transfered, at which time the board will be shut down to conserve on
Server space.

-----Original Message-----
From: George Richards P.E. [mailto:george(--nospam--at)] 
Sent: Wednesday, December 05, 2001 1:22 PM
To: 'seaint(--nospam--at)'
Subject: RE: Wood Moment Frame?

Why should the house survive undamaged after a big wind storm?  I
that is what insurance was for.  It should survive after a common wind
or earthquake for that matter but not the BIG ones.  I think the codes
now chasing their own tails in the sense that now in trying to make
everything stiffer, stronger, and better they have lost sight of their
intent, which I thought was life safety, not economic security.  The
reason the lawyers love us so is because we do not even know what we
any more.

Sorry for the rant, but living in the world of type V I see the code not
through rose colored but broken glasses, (sorry John could not resist

George Richards, P. E.  

-----Original Message-----
From: Dan Goodrich [mailto:dang(--nospam--at)]
Sent: Monday, December 03, 2001 9:18 AM
To: seaint(--nospam--at)
Subject: Re: Wood Moment Frame?

This was my concern from the start.  I got involved with the project
because of an issue with a suspended concrete floor slab.  As I was
going through the plans, I noticed the narrow shear walls.  Out of
curiosity I called the EOR to find out how he justified it.

Apparently, the report that John Rose mentioned is about to be
published.  This is the response I got from Tom Skaggs:

    "The information that you request has recently been finalized in APA
    T2001L-56 "Narrow Wood Portal-Frame Bracing Segments"."

I don't know when it will be available though.  He is going to mail me a
copy.  Thanks, John!

I think I have talked the EOR into using a Strongwall.  We'll see.
He did not perform a deflection check.  I doubt it would meet the
code requirements.  I've noticed that a few of the strongwalls have a
full height metal strap at the edge.  I wonder if this is to limit

George Richards asked "Where is the life safety issue?"
If only we had to worry about life safety.  What do you tell the
when the garage door won't open after the big wind storm because the
garage is slightly out of plumb?

Thanks for all the input.
Dan Goodrich, P.E.

---- Original Message -----
From: "chuckuc" <chuckuc(--nospam--at)>
To: <seaint(--nospam--at)>
Sent: Friday, November 30, 2001 11:31 PM
Subject: Re: Wood Moment Frame?

> The proposed wall has an aspect ratio of 5:1 and is not UBC compliant
> Fig. 23-II-I b)--and that should be the end of the discussion.
> It is certainly possible to build such a wall so as to meet the code
> required drift limits, but it is extremely difficult if the loads are
> (and you'd need lab tests to prove it).  Simpson (and a few others)
> gone to great lengths to fabricate and test code compliant portal
> frames--tell your guy to buy some.
> The aspect ratio multiplies all the sources of deflection:
> slop, shrinkage, tie down deflection, fastener deflection, plate
> etc. 5:1 is a killer and the problem is not amenable to accurate
> even if you tried to control all the construction variables. (I don't
> think Simpson's tests with green headers are accurate because they
> allow their headers to shrink before they tested them.)
> Chuck Utzman, P.E.

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ******** 

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ********