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RE: FW: R-values in Seismic Provisions

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The non structural mass would be there whether contributing to the stiffness
of the structure or not.

Regards,
Bill Allen

-----Original Message-----
From: La Count, Curt [mailto:Curt.LaCount(--nospam--at)Jacobs.com]
Sent: Wednesday, September 16, 1998 7:00 PM
To: seaoc
Subject: FW: FW: R-values in Seismic Provisions


To add my $.02;

It would depend on the ratio of the mass to the stiffness (that stiffness
contributing to the building stiffness).  If the non-structural elements had
a higher mass to stiffness ratio than the structural elements, then the
period would increase from the bare structural model.  The reverse would
also be true.  In any event, as the non-structural elements degrade and lose
stiffness (independant from other actions), the period of the structure
would increase.  T=2*pi*Sqrt(W/gk).

Curt La Count
Jacobs Engineering
Portland, OR.
 ----------
From: Majid Sarraf
To: seaint(--nospam--at)seaint.org
Subject: RE: FW: R-values in Seismic Provisions
Date: Wednesday, September 16, 1998 1:43PM

With all due respect to Mr. Hamburger, I agree with Bill and I must add that
Non-structural elemnts are indeed stiff but rather brittle elements that
provide
addiotional stiffness, by acting in parallel with the main structural frame.
They must incerease the overal stiffness which results in decreased period
(i.e. increased frequency) in the initial dynamic response, and later, as a
result of failure of these non-structural elements or their stiffness
degradation, overal stiffness reduces to that of the bare frame, and dynamic
response corresponding to the period based on the bare frame stiffness
should prevail.

Please feel free to correct me on this.


Regards,

Majid Sarraf