# RE: Concrete Strong Column/Weak Beam

• To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
• Subject: RE: Concrete Strong Column/Weak Beam
• From: "Yousefi, Ben" <Ben.Yousefi(--nospam--at)ci.sj.ca.us>
• Date: Thu, 21 Jun 2001 15:01:06 -0700
```The purpose of this check is to ensure that at the connection, the plastic
hinge does not occur in the column vs. the beam. This is a local check so to
speak, whereas the stability affects the global capacity of the column. The
same check is required for steel frames and there also, The Z*Fy of the
column is compared to the beam flexural capacity.

Ben Yousefi, SE
San Jose, CA

-----Original Message-----
From:	richard lewis [SMTP:rlewistx(--nospam--at)juno.com]
Sent:	Thursday, June 21, 2001 11:52 AM
To:	seaint(--nospam--at)seaint.org
Subject:	Re: Concrete Strong Column/Weak Beam

That is what puzzled me, "the flexural capacity of the columns is
affected by the coincident axial load".  Does it not matter how
slender a
column is when you check the flexural capacity based on the axial
capacity?

I take an interaction diagram, go up to the axial load and then go
across
to the curve boundary to find the moment capacity.  If it were a
column
design the moment capacity would be the magnified moment.  In this
check
it is just the moment capacity of the beam.

Rich

On Thu, 21 Jun 2001 10:16:41 -0700 "Mike Valley" <mtv(--nospam--at)skilling.com>
writes:
> Slenderness and P-delta do not play a part in this calculation.
The
> assumption is that flexural yielding will occur at every joint.
> The
> purpose of the calculation is to assure that the columns have
> sufficient flexural capacity to force yielding into the beams or
> girders.  Keep in mind that the flexural capacity of the columns
is
> affected by the coincident axial load.
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
> -
> Michael Valley, P.E., S.E.                   E-mail:
> mtv(--nospam--at)skilling.com
> Skilling Ward Magnusson Barkshire Inc.
> Tel:(206)292-1200
> 1301 Fifth Ave, #3200,  Seattle  WA 98101-2699      Fax:
> -1201
>
> -----Original Message-----
> From: richard lewis [mailto:rlewistx(--nospam--at)juno.com]
> Sent: Thursday, June 21, 2001 9:58 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Concrete Strong Column/Weak Beam
>
>
> I have a question regarding using ACI 21.4.2.2 check for the
strong
> column weak beam check.  How is column slenderness accounted for
in
> this
> check.  The ACI equation is :
>
> sum Me >= (6/5) sum Mg
>
> If I have a slender column, is Mg magnified somehow like in ACI
> 10.13.3?
> If I used a P-Delta analysis to get Mg, does it have to be
> magnified
> for
> this equation?  How does the effective length factor 'K' factor
> into
> this
> check?
>
> Rich
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