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Re: Foundation Min. reinforcement

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In my opinion, you have different issues here.  Continuous footings are
lightly loaded and continuously supported by soil, technically there is no
moment.  Top and bottom reinforcement is provided to control cracking and to
provide reinforcement for unanticipated moment due to varying soil pressure
distribution and settlement.  I do not consider continuous footings grade
beams.  Beam action may be required if shear wall segments are shorter than
the footing length required for pressure distribution on continuous footings
or post loads require distribution beyond that provided by a straight shear
distribution.  In this case the portion of the footing where beam action is
required is subject to minimum reinforcement requirements and the section
typically applied is 10.5.3, 1/3 greater than required up to the point of
convergence with 10.5.1.

Structural grade beams spanning between pad footings or piles (caissons) are
of two categories, those assumed to carry vertical and lateral loads or
those assumed to provide lateral resistance only (footing ties at frames,
etc.)  In both cases the grade beams should be designed as beams subject to
all the same requirements as any other elevated beam or frame member as the
case may be.

I heard rumors that the ACI was looking at upgrading the footing chapter to
clarify the requirements for grade beams as part of lateral frame systems,
maybe Scott can enlighten us as to whether this is true or not.

Paul Feather
----- Original Message -----
From: "Ed Najjarine" <enajjarine(--nospam--at)permasteelisausa.com>
To: "SEAINT (E-mail)" <seaint(--nospam--at)seaint.org>
Sent: Thursday, March 14, 2002 8:29 AM
Subject: Foundation Min. reinforcement


> Fellow Engineers,
>
> We normally design footings and grade beams with 1 or 2 # 5 T & B (or
> whatever is needed for the design moment) but we don't use the minimum
> reinforcement requirements for regular beams such as 200/Fy. Can you
direct
> me to where the code makes the distinction between regular beam
> reinforcement and grade beams.
>
> T.I.A.
>
> Ed Najjarine, P.E.
>
>
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