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# UBC' 97 Redundancy / Reliability Factor

• To: <seaint(--nospam--at)seaint.org>
• Subject: UBC' 97 Redundancy / Reliability Factor
• From: "Sasha Itsekson" <sasha(--nospam--at)ida-se.com>
• Date: Wed, 17 Mar 1999 08:56:30 -0800

```Hi,

I am wondering if I interpret 97 code correctly.

I have an existing masonry bearing wall building with an arched wood roof.
The footprint of the building is 100ft X 100ft.  The building is a single
story and it has on open front, solid back wall and 20ft long and 80 ft long
walls respectively on either side.

When calculating seismic forces using 97 code, it is seems like that the use
of the redundancy factor shall penalize this kind of building for having an
unbraced front side.

The calculations for the redundancy factor do not make much sense though.
According to the code, rmax factor for the direction parallel to the open
front is equal to the shear in the most heavily loaded wall (say 66 kips in
my case) multiplied by 10 and divided by length of the wall and divided by
total story shear(same 66 kips).  So I get 10/100 = 0.1 and redundancy
factor = 0 < 1.  So use p = 1.

No penalty for a faulty design!

Any thoughts?