Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: RetainPro

[Subject Prev][Subject Next][Thread Prev][Thread Next]
My comments are peppered throughout...

Bill Allen
> From: Michael Brooks <mdbrooks(--nospam--at)>
> To: Bill Allen, S.E. <BAllenSE(--nospam--at)>
> Subject: Re: RetainPro 
> Date: Friday, August 22, 1997 7:54 AM
> Dear Bill:
> At 06:46 AM 8/22/97 -0700, you wrote:
> >I agree with the problem with the analytical algorithms, but the most
> >prevelant method I've seen in practice (reality) is analyzing the wall
> >using EFP forces instead of using the Rankine method. Not being able to
> >even 1/3 * Ph generates an unacceptably conservative footing.
> All this discussion reinforces my belief that no-one really knows how to
> properly design a retaining wall. As "Structural Engineers" we should all
> have a definitive procedure for such a critical and commonplace
> element.

It _would_ be nice if all of structural engineering were "cookbook" to make
life easier for sofware authors. Unfortunately, this is not reality. I take
grievous offense to your belief that you think only you and your father can
properly design retaining walls since I don't believe you or your father
actually do that for a living.

> I can't believe, that after all these years, there are so many "beliefs"
> about how to apply Pv (or even where it comes from and how it can

> Most engineers nationwide are using our simple "EFP" method and ignoring
> (believe me...I talk to a LOT of engineers),

The reason most engineers use the EFP method is that this is the most
common criteria provided by either a building official or the typical soils
report. When was the last time you designed a retaining wall from a soils
report and not some pie in the sky theoretical soil coefficient?

> when it is so obvious that the
> more detailed approach is simple and appropriate.

The Rankine method is not difficult, but...see above.

> Ditto for walls with TOF a large distance below the soil surface.
> I think I will do some additional research to add to what our software
> (and I feel the best way is the Rankine method....internal friction
> are no big deal, really).

The Rankine method is not difficult, but...see above.

Stop trying to sell the Rankine method, I don't think it will work (the
sell, not the method).

> My father's short book "Basics of Retaining wall design" is excellent,
> with the addition of a few definitive topics on these so-called "grey
> areas", I think it would be doing our peers a great service.
> If you have any additional input please let me know so I can investigate.

Michael, I truely believe that you produce some of the best structural
engineering software out there. I also own both of your fathers
publications (retaining walls and tilt walls) and I strongly feel they
should be on every engineer's bookshelf. However, I think you, as a
software author, should spend more time listening to practicing engineers
(your customer base) rather than preaching to them.

> PS: You responded to me via the SEAOC list server by accident last time.
> would appreciate keeping private email private...thanks!

Sorry, it was no accident. This is an active topic and you are the author
of a piece of software a lot of engineers use. If you go back through the
dialog, it wasn't I who first referenced Retain Pro; I just responded to
comments that were part of the dialog. I thought it would be beneficial to
all for the list service to be aware of our dialog.

It just seems to me that it should be fairly easy to put a "check box" in
the program to allow the user to use Pv with EFP method, level backfill
even if only 1/3*Ph is used. For walls with a "zero" heel, maybe something
else to represent the friction between wall and backfill material (check
box w/input value?). This should be a tool to assist the engineer to do a
design consistent with their criteria, not yours. Times like this make me
miss your old spreadsheet days :o(

> Sincerely,
> Michael D. Brooks, S.E.
> President