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Re: Top Rebar??

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I asked S.K. Ghosh this exact question, and his answer was that the top bar
factor was not meant to apply to horizontal bars in walls. Furthermore, many
senior engineers that I know do not use it either.

----- Original Message -----
From: "Calvin Chang" <ccpe(--nospam--at)ms38.hinet.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Sunday, March 18, 2001 8:07 PM
Subject: Re: Top Rebar??


> >>
> Would this apply to all the horizontal bars in a 2 foot thick by 16 feet
> tall
> wall?
> <<
>
> Yes, I think so.
> Top bars must be HORIZONTAL BARS with 12 inches or more of fresh concrete
> below.
> All the main reinforcements of columns are not TOP BARS because they are
> VERTICAL BARS, even if the columns are very tall.
>
> Calvin Chang
>
> ----- Original Message -----
> From: <Tom.Hunt(--nospam--at)d-fd.com>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Sunday, March 18, 2001 8:49 AM
> Subject: Top Rebar??
>
>
> Speaking of seawater structures, I have received an interesting plan check
> comment.  We have designed a rather large double cell box culvert with
good
> size rebar vertically and horizontally in the walls due to a significant
> surcharge from a nearby railroad.  The plan checker has requested that we
> consider all HORIZONTAL wall bars as top bars in designing our splices.
> Now I know that the code reads that top bars are those with 12 inches or
> more of fresh concrete below but I have only used this in slabs and beams.
> I reviewed several texts and did not find anything definitive.
>
> When I was in school I was told that the top bar reduction was due to the
> possible accumulation of micro air bubbles rising to the surface.  Would
> this apply to all the horizontal bars in a 2 foot thick by 16 feet tall
> wall??  I have been given widely different opinions on both sides of the
> issue.
>
> Thomas Hunt, S.E.
> Duke/Fluor Daniel
>
>
>
>
>