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RE: when is a wall a column...now lateral ties for walls

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Dave:

Other people have said this stuff but here is my take on what the code
requires.


For walls ACI 14.3.6 specifically says "vertical reinforcement need not be
enclosed by lateral ties ... where vertical reinforcement is not required
for compression." If the reinforcement is not required for compression then
it is not required to be in ties unless it is required specifically by the
seismic code.

Also similarly for beams the last sentence of ACI 7.11.1 says compression
reinforcement requires ties and stirrups to be provided throughout the
distance the compression reinforcement is required.  It does not say ties
and stirrups are always required.

Scott M Haan P.E.
Plan Review Engineer
Building Safety Division 
Development Services Department
Municipality of Anchorage
http://www.muni.org/building
phone:907-343-8183  
fax:907-249-7399
mailto:haansm(--nospam--at)ci.anchorage.ak.us



-----Original Message-----
From: Dave Evans [mailto:DEvans(--nospam--at)tnh-inc.com]
Sent: Monday, October 08, 2001 4:11 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: when is a wall a column...now lateral ties for walls


Conrad raises an interesting issue regarding lateral ties for 
confinement of vertical reinforcment in concrete walls with two 
curtains.

Under in-plane deformation, under certain conditions, ACI 318-99 
requires lateral ties to confine the vertical reinforcement at the ends 
of walls, but not between the ends.

Under out-of-plane deformation, the requirement for confining 
vertical reinforcement in a wall is not so clear.  If one expects high 
compression strains in a two-curtain bearing wall due to out-of-
plane deformation, then presumably confinement reinforcement in 
the region of the high strains would be prudent.  Is anyone aware of 
literature that specifically addresses the issue of confinement for 
reliable out-of-plane seismic performance of doubly-reinforced 
concrete walls?

Dave



From:           	"Conrad Guymon" <conrad(--nospam--at)karren.com>
To:             	<seaint(--nospam--at)seaint.org>
Subject:        	Re: When is a wall a column?
Date sent:      	Mon, 8 Oct 2001 13:53:09 -0600
Send reply to:  	seaint(--nospam--at)seaint.org
Organization:   	http://www.seaint.org

> Robert C. Rogers wrote:
> 
> "Also note that ACI 14.3.6 tells you that if the
> predominant mode of loading is flexural and not compressive and the ties
> are not needed for the compression reinforcement then they can be
> ommitted (i.e., just vertical rebar and meeting the horizontal rebar
> requirements per 14.3.4).  Hope this helps....
> 
> If you are in an area of seismic risk, I wouldn't omit the ties..."
> 
> Conrad
> 
> 
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