Need a book? Engineering books recommendations...

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

RE: plan irregularity type 4 - 97 UBC

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Only the beam supporting the discontinuous shear wall needs to be designed for the omega factor. However, when designing the beam, one must account for the loss of cross section (both shear and moment) if the holddown has a threaded rod (SIMPSON's PHD, HD, etc.) The moment is the largest at the location of the holddown; the member has the least meat at the highest moment demand (if the threaded rod goes through the beam).


From: "Yousefi, Ben" <Ben.Yousefi(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: "'seaint(--nospam--at)'" <seaint(--nospam--at)>
Subject: RE: plan irregularity type 4 - 97 UBC
Date: Wed, 22 Jan 2003 07:43:03 -0800

-----Original Message-----
From: Mark Baker [mailto:shake4bake(--nospam--at)]
Sent: Tuesday, January 21, 2003 4:21 PM
To: seaint(--nospam--at)
Subject: plan irregularity type 4 - 97 UBC

I don't know how many times I have dragged myself through this, decided I am
correctly interpreting the application of omega, then 2 months later a plan
checker argues my interpretation resulting in my going through it all again.

Out of plane offsets of wood shear walls..... upper wall supported by beam
in floor, floor diaph. transfering load to offset walls below.

The easiest way to summarize my question to the list is this:

In this load path, where does omega get applied, feel free to put yes/no
behind the following items:

1. Apply omega to connection transfering lateral force from wall above to
beam.[Yousefi, Ben]  Definitely Not

2. Apply omega to hold down connections of upper wall to beam and beam to
columns.[Yousefi, Ben]  Absolutely Not

3. Design beam for omega level force from hold downs (overturning) and
compression (shear force).[Yousefi, Ben]  Positively Yes

4. Diaphragm force (keep in mind that diaphragm to be designed for Fpx load
plus load input from wall above (1633.2.9 item 2)[Yousefi, Ben]  No

4a. Apply omega to Fpx?[Yousefi, Ben]  No
4b. Apply omega to load from wall above?[Yousefi, Ben]  Question is not

5. Apply omega to shear walls below diaphragm (dependant upon awnser to 4a &
4b)?[Yousefi, Ben]  No

I would love to have a building official response but don't let that
discourage everyone else from their input. Ben Yousefi, are you out there?

One question you left out is: if the beam supporting the discontinuous shear wall is designed with Omega, should the connection for the beam, the columns
supporting it, etc, all be designed for Omega? The jury is still our on
that. My personal opinion is probably not. But, I could be wrong.

Ben Yousefi, SE
San Jose, CA



The new MSN 8: smart spam protection and 2 months FREE*

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
* * This email was sent to you via Structural Engineers * Association of Southern California (SEAOSC) server. To * subscribe (no fee) or UnSubscribe, please go to:
* Questions to seaint-ad(--nospam--at) 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: ******* ****** ****** ****** ******* ****** ****** ********