Need a book? Engineering books recommendations...

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

RE: Wood Construction Holdowns at Corners

[Subject Prev][Subject Next][Thread Prev][Thread Next]
If the earthquake comes at an angle that is not perpendicular to the
LFRS, you will get less than 100% in each principle direction. However,
in RIGID Diaphragm structure, you could get 100% with a head on EQ force
and still get a significant load perpendicular to the EQ force due to
the eccentricity of the Center of Rigidity and Center of Mass and then
accidental torsion and torsional irregularity.

I guess I would say that I don't disagree with you Bill, but I don't
think the effect is as great in a flexible diaphragm building. Chapter
16 defines flexible diaphragm if I'm not mistaken, but none-the-less, I
agree that the corner post should be checked for both directions and
some combo (be it 100-30 or SRSS) regardless of the diaphragm
classification.

-gerard
Santa Clara, CA


 
-----Original Message-----
From: Bill Allen [mailto:T.W.Allen(--nospam--at)cox.net] 
Sent: Friday, May 30, 2003 6:35 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Wood Construction Holdowns at Corners

Gerard -

I don't agree that this is a rigid diaphragm issue, that's why the
Orthogonal Effects requirement is in Chapter 16. 

I think the requirement is to account for the fact that the shock wave
will NOT hit the building perfectly aligned with one of the principal
axes. For this reason, I believe an Orthogonal Effects check is
necessary with structures with a flexible, rigid or semi-rigid
diaphragm.

Chris-

I'm not sure I can see the difference between a column common to two
perpendicular frames (moment or braced) as opposed to a column common to
two perpendicular shear walls. The mechanics are the same. The demand is
the same. The Orthogonal Effects requirement should be the same.

Regards,

T. William (Bill) Allen, S.E. (CA #2607)
V/F (949) 248-8588
San Juan Capistrano, CA


:-----Original Message-----
:From: Gerard Madden, SE [mailto:gmadden(--nospam--at)attbi.com] 
:Sent: Thursday, May 29, 2003 11:40 PM
:To: seaint(--nospam--at)seaint.org
:Subject: RE: Wood Construction Holdowns at Corners
:
:
:This gets back to rigid diaphragm argument and a code with 
:broad strokes. If the diaphragm rotates, the orthogonal 
:effects requirement is a valid check. The question remains as 
:to how rigid the wood frame building's diaphragm is to 
:necessitate this check.
:
:As far as how much axial load could a corner post be subjected 
:too, relatively speaking, it could be quite high or close to 
:capacity. Corner doesn't necessarily mean perimeter corner. 
:The OT chord force is the governing axial load, usually not 
:the gravity load.
:
:-gerard
:Santa Clara, CA
:
:-----Original Message-----
:From: Chris Roper [mailto:christophermroper(--nospam--at)hotmail.com] 
:Sent: Thursday, May 29, 2003 6:26 PM
:To: seaint(--nospam--at)seaint.org
:Subject: RE: Wood Construction Holdowns at Corners
:
:I think you guys are off the mark here.  I always thought that 
:this was 
:intended to apply to frame buildings where a column was part 
:of frames in 
:both orthogonal directions.  It seems silly to apply this to a 
:corner post 
:or column in a wood framed structure.  Besides, how much axial 
:load could 
:the corner post or stud be carrying in typical conditions?
:
:
:>From: "Bill Allen" <T.W.Allen(--nospam--at)cox.net>
:>Reply-To: <seaint(--nospam--at)seaint.org>
:>To: <seaint(--nospam--at)seaint.org>
:>Subject: RE: Wood Construction Holdowns at Corners
:>Date: Wed, 28 May 2003 14:12:49 -0700
:>
:>Pat-
:>
:>1997 UBC, section 1633.1
:>
:>Read the paragraph following the exception below "A column of a 
:>structure forms part of two or more intersecting 
:>lateral-force-rresisting systems."
:>
:>Regards,
:>
:>Bill
:>
:>
:>:-----Original Message-----
:>:From: Pat Clark [mailto:bcinc(--nospam--at)nanosecond.com]
:>:Sent: Wednesday, May 28, 2003 10:29 AM
:>:To: seaint(--nospam--at)seaint.org
:>:Subject: Re: Wood Construction Holdowns at Corners
:>:
:>:
:>:Bill, where do you find these factor for combining these hd forces?
:>:
:>:Pat Clark
:>:
:>
:>
:>
:>******* ****** ******* ******** ******* ******* ******* ***
:>*   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
:>******* ****** ****** ****** ******* ****** ****** ********
:
:_________________________________________________________________
:The new MSN 8: advanced junk mail protection and 2 months FREE*  
:http://join.msn.com/?page=features/junkmail
:
:
:******* ****** ******* ******** ******* ******* ******* ***
:*   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 
:******* ****** ****** ****** ******* ****** ****** ******** 
:



******* ****** ******* ******** ******* ******* ******* ***
*   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 
******* ****** ****** ****** ******* ****** ****** ********