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Posted by RicodJour on November 2, 2006, 5:10 pm
Mark wrote:
> >
> > You're doing a structural repair due to someone else failing to pay
> > attention to or understand the involved loads and material strengths.
> > I just checked your original post replacement thread - hadn't read it.
> > In one of your posts you pointed out that you felt a particular post
> > base would be insufficient as it only had a rated capacity of something
> > like 3500 pounds, yet your respond to my post about loads with an "I
> > have no idea".
> >
> > You seem to selectively address and ignore load information. Why is
> > that?
>
> My assertion that the EPB64 post base with a 3500 lb load capacity would
> be insufficient was strictly "from the gut." Having said that, I don't think
> it was an unreasonable concern. This is an indoor application, so I
> shouldn't
> need the standoff that the EPB series brackets provide. The ABA46 that
> I propose using is specifically intended for installation on a basement
> slab,
> and provides about 1" of standoff for good measure. It is also rated for
> about 10,000 lbs downward force. Simpson specifies that it may be filled
> with grout to "increase its capacity," although they don't specify what the
> higher capacity might be.
>
> Without a strain gauge, I cannot tell what the actual loading is on the
> existing
> post. Perhaps it is less than 3500 lbs, but I am more comfortable with
> 10,000 lbs capacity.
>
> The existing 4x4 post has stood for 75 years without any obvious distress
> in the slab, so I have no reason to believe that it won't serve as a
> suitable
> base for a 4x6 replacement column. Of course there _may_ be an integral
> footing in the slab at that point. Unlikely, but possible.
>
> I plan to use a CC3-1/4-6 post cap, which is made from 7 gauge steel and
> spreads the load over 11 inches. I hope that will be sufficient so that the
> post no longer exceeds the crush strength of the paired two-by joist.
You seem to be a methodical guy. Which makes it a little difficult to
follow your reasoning in basing your design on a failed installation
that almost assuredly doesn't meet code (code being the minimum
acceptable construction).
In the amount of time it took you to investigate the post bases you
could have determined exactly what the design load is so you wouldn't
be guessing. Unless you have a large amount of experience in
structures, "from the gut" equates to "wild assed guess". If you need
a little assistance in figuring out how to calculate the loads, just
say so. I assure you that even someone as experienced as Bob Morrison,
engineer extraordinaire, has had to ask some questions - and I've been
happy to answer them! ;)
R
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