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RE: Kneebraced Post Design

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Chris,

This kind of thing is right up my alley. I remember doing a raised deck for
a frat house in Boulder, CO about 10 years ago that had a hot tub on it!
That one used knee braces and was very stout, however, I have on occasion a
need for the type you describe. Is there anyway you could provide more
detail of your connection?

Michel Blangy, P.E.




> -----Original Message-----
> From: chris.slater(--nospam--at)gmail.com [mailto:chris.slater(--nospam--at)gmail.com]On Behalf Of
> Chris Slater
> Sent: Friday, May 09, 2008 2:47 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Kneebraced Post Design
>
>
> Tried sending this earlier, and it never made it.  I'm assuming the
> list doesn't like attachments.  Instead, I've included a link to the
> file on my web server.
>
> --
>
> A lot of our firm's work is residential, and of that, a moderate
> percentage is small additions and remodels.
>
> One thing that we see very often (and more frequently as jurisdictions
> start getting tougher about requirements) is small covered patio
> additions.
>
> Engineering the lateral support for these is tricky.  The favored
> solution for owners and contractors is to kneebrace the support posts.
> We've done this in the past, and made it work for small patios, using
> NDS combined lateral and pullout values for Lag Screws, and an R value
> of 4.5 (UBC).
>
> In the new code, we have to use R=1.5, which means that even for a
> small patio, the seismic load is fairly high, and it is very difficult
> to make this work.  However, in an effort to not have to specify steel
> columms for every little patio we engineer, we've tried to look at
> other options, such as 1/4" steel side plates with either lag screws
> or through bolts.
>
> I developed a spreadsheet, using the NDS equations, that gives options
> based on what we put into it.  I've attached the spreadsheet to this
> e-mail (actually, it's here:
> examplecalcs.com/Kneebraced%20Post%20Design.xls)
> and would appreciate it if any of you had time to review it and
> offer feedback.  If you find it useful, please feel free to keep a
> copy.
>
> So the request for feedback is my first request.  But I also am
> interested in what others are doing with regard to small patios and
> knee braced posts.  I know that this type of thing falls way below the
> radar of many on this list, but it is something we run into very often
> in our practice.
>
> Thanks,
>
> Chris Slater
>
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