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Re: Top Rebar??

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>>
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