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RE: IBC and Rho factor

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Ben,
Giving this some further thought, I don't believe that engineers are off
the hook from potential liablity. Here is my opinion on the issues.

A building department can adopt and accept anything that they believe to
be valid or reasonable for the design of a structure. They can not,
however, reliquish the engineer of record from potential liablity if the
results of his or her design is less than that which would be the result
of compliance to the current code in force - the 97 UBC. The building
official is not liable - even if he or she provides the wrong advice to
the design engineer and the engineer assumes all responsibility should
he or she be challenged in court.

If the 2003 IBC is adopted by the state of California and then adopted
by each jurisdiction, the engineer would be free of liability to conform
to the code. However, if the Tri-County and the city of Los Angeles
chooses to accept work based on the wording of the 2003 IBC code and
even amends a policy in that jurisdiction, the results of the revised
code acceptance, but be sure to produce results that are equal or
stricter than what is currently adopted in California as the 97 UBC or
98 CBC.

Please correct me if I am wrong. The city has decided to be lenient on
the issue of design, yet in a courtroom, the engineer is required to
design to whichever his the law in the state and the local jurisdication
can not adjust the law to something less restrictive without changing
the state code or law first.

If there are any expert witnesses or legal minds out there I would like
a ruling on this. I know that our local jurisdiction will require a
change in the code that is approved first at the state level and not
simply adopted by any one jurisdiction no matter how powerful it might
be. If the building official carries no liability, the design engineer
should be very careful what he or she accepts to be the standard of
professional practice.

Cautiously,
Dennis

-----Original Message-----
From: Yousefi, Ben [mailto:Ben.Yousefi(--nospam--at)ci.sj.ca.us] 
Sent: Wednesday, October 02, 2002 3:21 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: IBC and Rho factor


Dennis, please see my answers below:

-----Original Message-----
From: Structuralist [mailto:dennis.wish(--nospam--at)verizon.net]
Sent: Wednesday, October 02, 2002 2:29 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: IBC and Rho factor


Ben,
I'm no longer an SEA member so I won't be receiving the notes from this
presentation. What I want to ask is this:

1. The 20% increase that you are refering to is the difference between
2.5Wd/(1.4R) and 3.0Wd/(1.4R) I take it???

(BY)Yes

2. Don't you require V=3.0Wd/(1.4R) to be multiplied by a Rho of 1.5?

(BY)No

3. Do you consider plywood covered in lightweight concrete to be
flexible or rigid?

(BY) Yes. The concrete topping is not a continuous diaphragm, it is
discontinued by wall sill plates and there is no documentations that
proves it causes the plywood to act rigid.

4. Doesn't the code still require the engineer to calculate the
deflection of the diaphragm before assuming it is flexible and using the
Simplfied Static Method? This was my interpretation of the code as I
could not find any specific wording that stated the engineer may use
flexible diaprhagm analysis for a wood structure three stories or less
based on Simplified Static proceedures. My interpretation has always
been that the engineer must first calculate the diaprhagm deflection. Is
the assumption of flexible diaphram only the Tri-County's comprimise on
the issues?

(BY) No, if you comply with the simplified method provisions. For all
other cases you are correct. The new policy (amendment) that I was
referring to which will be adopted November 1 by most LA and Bay area
jurisdictions, is modeled after the new language in 2003 IBC and it
reads as follows:

"1630.2.3.4	Horizontal Distribution.  Diaphragms constructed of
untopped
steel decking or wood structural panels or similar light-frame
construction are permitted to be considered as flexible"



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