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RE: 97 UBC Lateral force on elements of structures

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In this example they also apply the minima to each location resulting in the
minima at elevation 0 being averaged with the formula value at the roof. If
you use the average height instead you get a significantly lower result.

It also makes sense NOT to include the rho factor in these instances. Rho
does not represent a real force but is a penalty for the lateral load
resisting system on a system wide basis. The connection forces and element
forces are already significantly amplified.

-----Original Message-----
From: Rick.Drake(--nospam--at) [mailto:Rick.Drake(--nospam--at)]
Sent: Tuesday, October 19, 1999 9:52 AM
To: seaint(--nospam--at)
Subject: Re: 97 UBC Lateral force on elements of structures

Robert Shaffer <rkdn(--nospam--at)> on 10/19/99 10:07:03 AM

There is a good example of this calculation in the Seismic Design Manuel,
Vol 1 by SEAOC and ICBO.

They calculate the value of Fp for each diaphragm elevation and then average
w = [(Fp1x + Fp2x)/2] * W  .

It seems that there is contradictory language in the code as to the
application of Rho to Fp.  In 1630.1 the definition of Eh includes Fp,  but
then in 1632.2 it indicates to set Rho equal to 1.0.