Winter 2007
Dear Colleague:

Using Retain Pro 2007?
We hope you like it!
If you haven't upgraded, here's what's new...

  • Design segmental retaining walls (SRWs), either gravity or with geogrids (MSE).
  • LRFD option for masonry for more economical designs
  • Equation Menu to quick-solve over a dozen complex equations in seconds!
  • Pier foundation option (free downloadable add-on coming by 3/31 - see below)
  • Other improvements and continuing updates and enhancements via AutoUpdate.
  • FREE copy of 7th edition of Basics of Retaining Wall Design (until 4-30-07)
Now available:
7th Edition of Basics of Retaining Wall Design
Over 30% more information and
nearly every topic expanded, plus new subjects.

It's FREE with every Retain Pro order until 4-30-07 (Regular: $65)

See below for contents:

Our licensing policy

We continue to get questions about our licensing policies, so here it is again:

Our "Small office license" is for the 80% of our users who are smaller offices. It allows you to install (using your PAC) on up to four office/home/laptop computers, but only one simultaneous user is allowed. If installed on a server a second simultaneous user will be stopped. The "Site license" is for large offices installing on a network server with unlimited access by any number of engineers, but at one physical site.

BTW, we're seeing an increasing number of large companies adding Retain Pro for their branch offices - we do offer discounts for branch offices.

We've added TechLinks

A TechLinks button has been added to our home page (upper right). Click here and you'll find links to sites related to retaining walls and other web sites of interest. For example, the links to obtain seismic design data from USGS by entering zip code or latitude/longitude. Also earthquake information and activity maps for both the US and for Californians a map of seismic events updated hourly (average about 50 "events" each day!). Check out the links and let us know of other favorites you have and we'll post them. You can also copy and paste them into your favorite places.

More coming with AutoUpdate

Although there are no updates available now, some of you reported a "file not found" message when clicking YES when asked if you want to check for updates. This indicates a problem with your installation of RetainPro. The file named "RPUPDT2007.EXE" performs the actual check for updates and should be in your RetainPro folder and easily found and run.

If the update does not start from within Retain Pro you can run the updating program from your Retain Pro program group by selecting Start | Programs | Retain Pro 2007 | RP 2007 Auto-Update.

The first update will be available about April 3rd. At that time click YES when asked to check for updates, and check every few weeks thereafter. In this first download you will get:

  • Pier foundation feature activated
  • More vendors added to segmental retaining walls.
  • Corrected CRSI equation in the Equation Menu
  • Activated DXF file for segmental walls.
  • Some reported problems fixed

Technical Issues

Using LRFD for masonry
This new feature in Retain Pro 2007 will result in more economical designs. It follows IBC '06 and ACI 530-05, and can be selected under Design Method on the Stem Design screen. Use it. Your client and the contractor will benefit.

Use of vertical component of active pressure
This was discussed in our Summer 2006 newsletter but we still get questions about this. For every design you should check what you have chosen on the Options screen since what you selected for a previous design may not be appropriate for a new design. We recommend only checking its use for resisting overturning (advised by Bowles), however other texts (Das, for example) also uses it for sliding and soil pressure reduction. Use caution if using it for soil pressure reduction since applying this force to the back of a long heel can make a dramatic and probably unwarranted change in soil pressure.

Global slope stability
Please note that Retain Pro does NOT check for global stability. This analysis could be recommended by the geotechnical engineer when underlying soil is susceptible to mass rotation and is most often recommended for tiered walls and segmental MSE walls. Software is available for doing this (not inexpensive), however this analysis is best deferred to the geotechnical consultant.

Liquid retention
Water retention ponds and containment of other liquids are a frequent design task.
Here are procedures for using Retain Pro 2007 for these cases:

  1. Set heel active pressure to 62.4 pcf (some use 64 pcf for "dirty water")
  2. Set "retained height" as the height of liquid over the footing
  3. Set "soil height over toe" not more than about one-half the "retained height" (see Negative Overturning below).
  4. Set Density same as heel active pressure.
  5. On Load Factors set "H" to 1.2 (defined liquid per ASCE 7-05, 2.3.2(2)).
  6. Set Toe Side Active pressure as 30 pcf or 35 pcf.

If water can seep under the footing the pressure above and below the footing will be neutralized, therefore the weight of water over the footing (pressure on the top of the footing) cannot be used to resist overturning. For this case enter 1 pcf for "density" (the program will not accept a zero value for density). However, be aware that if you enter 1 pcf for density the program will also use this for the toe side (we'll correct this in a forthcoming AutoUpdate) resulting in a slight error in soil pressure and overturning. For buoyant effect you can change the weight of the footing on the Material screen.

To check the wall when water is empty and earth is present on the toe side, you will need to do a reverse design since the program will not accept a negative (clockwise) overturning. Do a mirror-image design with the earth is on the heel side.

Negative overturning
By convention, Retain Pro assumes the net forces on the wall cause counterclockwise overturning - retained material on the right-hand side of the wall. If you get a negative overturning, such as an empty detention pond with earth on the outside, you need to do a supplemental mirror-image design (i.e flip the wall).

Counterfort retaining walls
Their design is not in Retain Pro (yet) but the 7th edition of Basics of Retaining Wall Design has a design procedure described. Also, equations in the Equation Menu (version 2007) will help design the counterforts.

Circular pier/column design
The upcoming pier foundation feature requires checking the moment capacity of a spirally reinforced "column". This is a complex analysis task since the "Whitney Stress Block" is a segment of a circle, but we use the Whitney Approximation Method, proposed by Charles Whitney in an ASCE Transaction paper in 1942, using an equivalent rectangular section. This approximation method yields conservative (by 5% - 10%) results. This method is also added to the Equation Menu in the next AutoUpdate. The procedure is also described in Basics of Retaining Wall Design.

About verifying results

You want to feel comfortable with any software you are using. Although nearly every reported Retain Pro "error" is traced to faulty input, legitimate errors can and do occur. Retain Pro contains over 100,000 lines of programming code packed into nearly 4 MB, so there is always a chance for error. We investigate every report and remedy a problem as quickly as we can. Most errors can be easily spotted since an aberrant result is obvious to an experienced user, but if any result is suspect, you should verify it with a hand calculation. With very few exceptions, any result in Retain Pro can be verified by a five minute hand calculation! I recently talked with a user who questioned a result and spent considerable time trying to reconcile CalcTrac with the result. He could have saved the time with a quick calc. I faxed him my verifying calculation which took me three minutes, and I'm not particularly fast. (we plan to delete CalcTrac since it is not a complete trace of all calculations and can sometimes be difficult to follow, but more importantly it fosters reliance on output rather than encouraging you to perform your own verification).

My point: If you suspect a result, and have checked your input, do a hand calc. You'll benefit from the exercise, and if you do catch an error, we benefit too!

Incognizance award (meaning unaware of what one is doing)

Occasionally we get tech support questions that would be humorous if they weren't serious. Here is one prize winner:
The user who questioned the excessive overturning moment when retaining water.
It turned out he had input a 2:1 backfill slope!

The moral: Always check the applicability of ALL your input entries, particularly if retaining liquids.

Access past newsletters

They are all posted on our NEWSLETTERS link on our home page. Lots of good information and Technical Issues for your review.

Suggestions and comments

If you have suggestions, comments, or corrections on these Newsletters, or a technical item to contribute, we want to hear from you. Email me at hbrooks@retainpro.com. Remember to check Open Tech Forum (bottom of home page) for other announcements and user posts. We also encourage you to post a review of Basics of Retaining Wall Design. Click on Submit Review at lower left of home page.

With best wishes,

Hugh

Hugh Brooks, SE
Retain Pro Software

If you haven't upgraded to Retain Pro 2007 we offer five-minute delivery to your computer, plus the new User's Manual and the free copy of Basics of Retaining Wall Design, for just $195. ($295 if upgrading from version 6.1 or earlier). To order click here or visit us at www.retainpro.com. Offer valid until 4-30-07.

P.S. You are receiving this email because you are a Retain Pro user or have downloaded a demo and asked to be on our email list. This email list is for our use only to provide you with information, but if you do not want to receive future copies just email me at hbrooks@retainpro.com and on the subject line type "Cancel", and don't forget to include your company name and email address where you received this.

Retain Pro Software div. HBA Publications, Inc. PO Box 826 Corona del Mar CA 92626 949-721-4099 hbrooks@retainpro.com
© 2007 HBA Publications, Inc. All Rights Reserved.