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Re: pier design

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Suggestion, If you do or anticipate doing much pier work Go straight to L-Pile do not
pass Broms.

Michael Donoghue PE


Arvel L. Williams, P.E. wrote:

> MarthaAlic wrote:
>
> > I am currently designing a roof platform. The lateral resisting system is
> > composed of moment frames running in both directions. This platform is exposed
> > and due to space limitations, I have no other choice than using drilled piers
> > for foundations.  For the embendement length, I divided the moment by the
> > shear at the base and found an equivalent height for the shear load (ie.
> > M/V=h'). My questions are:
> >
> > 1. What is the minimum reinf. required.
>
> > 2. Do I have to design the pier as if it were a column with and axial and
> > amoment (eventhough it is lateraly braced by the soil) or should I justconsider
> > the moment.
>
> I  develope an interaction diagram for the piers to determine reinforcing steel
> requirements using ACI 318-95.
>
> > 3. Is there a source I can use as a guideline for my design.
> >
>
> The simplest method I've found, in a uniform soil, to determine the moments and
> shear is Brom's theory from 1964.  It is describe by Poulos & Davis in their text
> published in 1980.
>
> If the situation is critical, I'd consider using one of the finite difference
> solutions with P-Y data.  If your not familiar with P-Y curves there is some
> guidance in Poulos & Davis.
>
> Also check out Bowle Fifth Edition of his text.  It is usually straight forward
> and has alternative methods.
>
> If this is a layered soil site it might be a good idea to get assistance from a
> geotech engineer with experience in designing laterally loaded piles using
> computer aids such as L-Pile or PileDG.
>
> Arvel L. Williams, P.E.
>