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Re: Fixed base timber column

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Isn't this construction similar to a  fence (except the size and configuration
of the members)? Why not build it like one? Use a good grade of outdoor lumber
like cedar for your posts. Embed the verticals in the ground in stone or
concrete to get your fixity. You may even want to treat the embedded end to
increase the resistance to rot. If you embed the posts in concrete, make sure
you detail the top of the concrete to pitch away from the post so that water
doesn't lay against it. You may have to increase the hole diameter to 24" to
totally encase your 10 x 10 columns. Granted this may not prevent the posts from
ultimately rotting out, but how long does the owner expect it to
long as a fence......or as long as his house?

The other possiblity, is to architecturally incorporate some returns at
strategic locations to brace the trellis. This might also create some additional

Jim Kestner, P.E.
Green Bay, Wi.

Thomas Long wrote:

> I am designing a free standing trellis.  The footprint is about 100ft x
> 20ft.  The owner wants to use 10x10 timber columns, 10x12 beams with 4x8
> lattice at 36" o/c.  The columns are founded on 18" diameter caissons.  The
> timber columns are spaced at 14'-0".
> The owner would not like to see the typical knee braces to support the
> timber frame from lateral movement, and no exposed connections.  I have been
> tossing ideas around in my head about how to approach this fixed base timber
> column condition.
> The ideas I have come up with are:
> 1. Use a vertical steel plate in the center of the column and bolt through
> and plug the holes.  I do not feel to good about this.
> 2. Embed threaded rods into the concrete either when they pour the caissons
> or then drill into the column and install with epoxy adhesive.  Not a bad
> solution, but how do I design it.
> 3. Embed a 2" +- pipe column into the concrete and drill the column and then
> bolt through and plug.  Hard to drill into the timber and to construct.
> Has any body designed a structure like this and if there is, how did you do
> it, what is the best solution.
> Thank you in advance.
> Thomas Long
> Thomas Long Engineering