Return to index: [Subject] [Thread] [Date] [Author]

RE: Plan Irregularity Type 5

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Not Parallel is correct. Center of Rigidity vs. Center of Mass with
accidental torsion is taking care of the "Non-symmettric" and it's not a
plan irregularity. Use the 100%-30% rule or SRSS analysis.

Hth,
-gm

-----Original Message-----
From: Paul Crocker [mailto:pcrocker(--nospam--at)reidmidd.com]
Sent: Thursday, May 05, 2005 4:01 PM
To: seaint(--nospam--at)seaint.org
Subject: Plan Irregularity Type 5

A question has arisen recently among a few engineers locally about the
meaning of a Type 5 plan irregularity.  I have always thought of this as
a non-orthogal systems irregularity, but looking at ASCE 7-02 Table
9.5.2.3.2, the definition is: "The vertical lateral force-resisting
system elements are not parallel to or symmetric about the major
orthogonal axis of the lateral force resisting system."  The
interpretation, that had never occured to me, is that the "or" in the
sentence means that it applies to either non-parallel systems or
non-symmetric systems.  Since 95% of layouts are not perfectly
symmetric, 95% of buildings would have a Type 5 irregularity.  I have
not understood this to be the meaning of the irregularity, but I don't
see how I can adequately explain the "or symmetric" part.  Does anyone
have any insight into this?

Paul
  


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********