Tuesday, September 13, 2011

Re: ASCE 7-05 Section

The second part is addressing each line of resistance, not the entire building.

-----Original Message-----
From: Jason Christensen <jason@wcaeng.com>
To: seaint <seaint@seaint.org>
Sent: Tue, Sep 13, 2011 2:57 pm
Subject: ASCE 7-05 Section

Can anyone expand on the second sentence in this section?  It seems to mean  nothing, considering the requirement of the first sentence. R, Cd , and Ω0 Values for Horizontal Combinations. Where a combination of different structural systems is utilized to resist lateral forces in the same direction, the value of R used for design in that direction shall not be greater than the least value of R for any of the systems utilized in that direction. Resisting elements are permitted to be designed using the least value of R for the different structural systems found in each independent line of resistance if the following three conditions are met: (1) Occupancy Category I or II building, (2) two stories or less in height, and (3) use of light-frame construction or flexible diaphragms. The value of R used for design of diaphragms in such structures shall not be greater than the least value for any of the systems utilized in that same direction.  Maybe I am missing something, but it seems to say in the first sentence that you  have to use the least R values (which makes sense), but the second sentence  seems to be giving an exception if the three criteria are met, however it still  states that the least R values is to be used.   Any thoughts would be helpful.  Jason  ******* ****** ******* ******** ******* ******* ******* *** *   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@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 ******* ****** ****** ****** ******* ****** ****** ********