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Re: Landslide

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Caldwell, Stan wrote:

> Generally the soils engineers recommend a minimum of a twelve inch
> >diameter pier with four number four bars and #3 ties at varied spacing.

This looks like a rehash of a very old federal housing specification from
1963 for a minimum drilled shaft and grade beam pier foundation. That
document indicated 12 inch piers with a single #5 bar and no spiral cast
into a grade beam with two (2) #5's.

> Whoa!  When did geotechs start specifying concrete reinforcement?  Where
> did they get that expertise?  Don't they have enough liability within
> their own profession?

I practice geotech, and on occasion have recommended minimum steel and
concrete diameters, especially with laterally loaded drilled shaft concrete
piles.  I don't hold my self out to be a structural engineer, however, I
feel confident that I can design foundation systems.

> What self-respecting structural engineer would design concrete in
> accordance with a geotech's specifications?  IMHO, the geotech should give
> us the soils forces, resistances, and stiffnesses (if applicable), and
> geotechnical construction guidelines
> (if appropriate), and then get out of our way!  In other words, all of
> the geotechnical design criteria, but only the geotechnical design
> criteria.

Many structural engineers appreciate a geotech solving the lateral load case
with soil-strucute interaction.  On the other hand, some engineers just want
the design criteria, which from a liability standpoint is just fine with
me.  Actually, either case is fine by me.

> *************************************************
> Let my words be sweet and tender today,
> for I may have to eat them tomorrow!
>                                         ...anonymous
> *************************************************

Hmm, will you have the white or red wine with your previous post.

Arvel L. Williams, P.E.