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

RE: Chords in concrete and masonry buildings

[Subject Prev][Subject Next][Thread Prev][Thread Next]
UBC 97, Chapter 21, Part 2106, General Design Requirements

Paragraph 2106.1.12.3 Special Provisions for Seismic Zone 2 requires a
continuos bond beam at roofs, floors, and tops of walls of at least 0.2 sq.
in (#4) for running bond and 0.0007bt for stack bond.

Paragraph 2106.1.12.4 Special Provisions for Seismic Zones 3 & 4 adds
additional steel to Zone 2 requirements (except for some occupancies). The
minimum sum of horizontal and vertical wall reinforcement is 0.002bt, with
the minimum in one direction of 0.007bt. Maximum reinforcing spacing is 4
ft.

The bond beams at the floors and roof act as the chord of the horizontal
diaphragm as well as increasing the development of the ledger anchor bolts.

-----Original Message-----
From: Rodriguez, Marlou [mailto:mrodriguez(--nospam--at)BiggsCardosa.com]
Sent: Thursday, September 28, 2000 8:02 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Chords in concrete and masonry buildings


Good point Jeff,

thanks
-----Original Message-----
From: Jeff Coronado [mailto:"jcse(--nospam--at)flash.net"@flash.net]
Sent: Thursday, September 28, 2000 7:36 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Chords in concrete and masonry buildings


Marlou,

I don't believe this represents a code violation, but it doesn't sound
like a good idea.  Putting in an extra bar or two horizontally at the
top of the wall seems so simple.  You must have a pretty good reason for
considering not following this path.

My concern is that using the ledger is not standard practice, unless
others correct me on this.  My concern is that 5, 10, 20 years from now,
and after the drawings may have been lost, a new owner is going to
retain another engineer for a T.I.  That engineer will appropriately
assume the chord is in the wall.  They will be careful to not cut
reinforcement.  They will think nothing of cutting or butchering the
ledger.  Maybe a heavy connection butchers the ledger.  Maybe a new beam
and column against the wall cuts the ledger.  I would try to stick with
standard practice.

Jeff Coronado, S.E.
West Covina, CA

Rodriguez, Marlou wrote:
> 
> When designing a concrete or masonry shearwall building with flexible roof
> or floor diaphragm, does the chord have to be taken by continuous bars in
> the concrete or masonry that are placed at the elevation of your
diaphragm,
> even if you have steel ledgers that are continuous at the perimeter of the
> diaphragm.  Could the steel ledger be used as a chord? or is this against
> the code.
> 
> TIA
> 
> Marlou
> 
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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) to the list, send email to
> *   admin(--nospam--at)seaint.org and in the body of the message type
> *   "join seaint" (no quotes). To Unsubscribe, send email
> *   to admin(--nospam--at)seaint.org and in the body of the message
> *   type "leave seaint" (no quotes). For questions, send
> *   email 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) to the list, send email to 
*   admin(--nospam--at)seaint.org and in the body of the message type 
*   "join seaint" (no quotes). To Unsubscribe, send email 
*   to admin(--nospam--at)seaint.org and in the body of the message 
*   type "leave seaint" (no quotes). For questions, send 
*   email 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) to the list, send email to 
*   admin(--nospam--at)seaint.org and in the body of the message type 
*   "join seaint" (no quotes). To Unsubscribe, send email 
*   to admin(--nospam--at)seaint.org and in the body of the message 
*   type "leave seaint" (no quotes). For questions, send 
*   email 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) to the list, send email to 
*   admin(--nospam--at)seaint.org and in the body of the message type 
*   "join seaint" (no quotes). To Unsubscribe, send email 
*   to admin(--nospam--at)seaint.org and in the body of the message 
*   type "leave seaint" (no quotes). For questions, send 
*   email 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 
******* ****** ****** ****** ******* ****** ****** ********