Yes, the 40 times diameter requirement is more an older rule of thumb,
but it still shows up in many (probably the majority) of the references
I found. That's why I qualified my comment by saying it depends on the
application and jurisdiction. I could have sworn there was a section on
rebar splicing in the International Residential Code, though, but I
couldn't find it when I checked last night.
I had to have my rebar cage checked by the building inspector before the
pour and he signed off on it. That doesn't mean much, of course, but at
least the rule of 40 probably has some historical leverage. The most
logical way to find out what the local requirement is would be to just
call the zoning commission and ask.
That pdf file looks like a great reference, by the way ... thanks for
posting it.
73,
Dave AB7E
On 1/4/2014 7:52 AM, Jim Lux wrote:
On 1/4/14 6:02 AM, Patrick Greenlee wrote:
A very robust cage you have there, David. Could you site where the 40
times diameter is written? I learned by watching and asking questions
of contractors and was told 25 times diameter by more than one and no
other value. I will have to look for a reference as I have no alternate
experience. Thanks for mentioning 40 as that provides incentive to do
some research. Oh by the way... although I demand code or better
whenever possible in all endeavors the only inspection I have had
building two houses and installing a tower has been by the DEQ
(Department of Environmental Quality) who inspect and permit septic
systems (my installer was lisc to self inspect.)
googling "rebar overlap" or "rebar lap splice" turns up a wealth of
conflicting information.
You might look at UBC 1912.1-1912.15
Apparently the 40xdiameter is an older rule of thumb/code and modern
codes vary the length of splice depending on the kind of steel,
strength of concrete, application, amount of concrete cover, and
spacing of the bars.
There's also differences depending on the year of the code and what
the application is (e.g. rebar in a masonry wall footing might be
different than in a flat slab might be different than in a poured
concrete wall, etc.)
Here's a chart
http://www.monolithic.com/stories/rebar-splicing-and-rebar-sizing
they talk a lot about complying with code, but don't say which one.
Here's a whole handbook on splicing:
http://www.daytonsuperior.com/Artifacts/DS_Rebar_Splicing_HB.pdf
Page 10 has what you're looking for.
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