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Re: IBC and Rho factor

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Dennis-
I believe you are correct. This issue is about to be further clarified,
if & when the Gov. signs SB800. Here is the salient section:

>(4) A structure shall be constructed so as to materially comply
>with the design criteria for earthquake and wind load resistance, as
>set forth in the applicable government building codes, regulations,
>and ordinances in effect at the time of original construction.
>
As I understand the matter of local code modification, local
jurisdictions may alter the provisions of the State Code by conducting
local legislative hearings that demonstrate that local conditions are
significantly different, and thus require different code provisions.
(local Fire Departments do this regularly around here). The local CBO is
not the Emperor of the North Pole, able to rewrite black letter code at
his own discretion. The local City Council must have hearings & adopt an
amending ordinance in order to change the provisions of the CBC.
Chuck Utzman,P.E.

Structuralist wrote:

>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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