# RE: redundancy factor

• To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
• Subject: RE: redundancy factor
• From: "Cain, William" <bcain(--nospam--at)ebmud.com>
• Date: Wed, 17 May 2000 13:58:05 -0700
```Wait until you get to the IBC 2000.  In calculating the rho factor, they
limit r (did they really mean rho?  :<)  ) by the statement: "shall not be
less than 1.0, and need not exceed 1.5" (Section 1617.2.2).

Since rmaxi is defined as "the ratio of the design story shear resisted by
the most heavily loaded single element in the story to the total story
shear, for a given direction of loading" the effect would be to raise
calculated rho values because this wording would assign from 1 to 1.5 times
the TOTAL STORY SHEAR  to the single most heavily loaded element.
Personally, I think this is yet another formula screw-up in the IBC as I
assume it is intended to be basically the same as the 97UBC which limits rho
to being within this range.  But one never knows........  [ROTFL].

Regards,
Bill Cain, S.E.
Oakland  CA

-----Original Message-----
From:	Paul Crocker [SMTP:paulc(--nospam--at)ckcps.com]
Sent:	Wednesday, May 17, 2000 4:29 AM
To:	'seaint(--nospam--at)seaint.org'
Subject:	RE: redundancy factor

The definition of r(max) used in the redundancy equation is based on
the
worst case that occurs below the 2/3 point of the building for a
given
direction (1630.1.1).  Hence, if your first floor requires 1.2 in
one
direction, you must use 1.2 on your second floor in that direction,
too.

Paul Crocker

-----Original Message-----
From: Francisco Duarte [mailto:fduarte(--nospam--at)LEASUNG.COM]
Sent: Wednesday, May 17, 2000 9:55 AM
To: seaint(--nospam--at)seaint.org
Subject: redundancy factor

Let say you are designing a two story building and in your
redundancy check
you calc. out redundancy= 1.0 for all the second story force but
once you
are in the first floor you calc. out a redundancy=1.2 on one
direction. Now
my question is do you must increase the second story force in the
same
direction by the 1.2 factor or you just do the 1.2 increase in the
first
floor at that specific direction ?
any help will be much appreciated.

Francisco Duarte,E.I.T.

```