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Summer 2010
Dear Colleague:

These quarterly newsletters (this is our 18th) are sent to all Retain Pro 9 users and those who have asked to be on our recipient list. All previous copies can be read from the link on our home page - there's valuable technical information in each.

If you are not the right recipient for this newsletter please update our database at And pass this along if you are not the right recipient.

Retain Pro 9 latest releases

The latest release is 9.13 which is available via AutoUpdate or downloadable from Changes on this release can be viewed on Retain Pro 9 Advisor, which is on our home page. An archive of changes on all previous updates to Retain Pro 9 can be viewed at -- click on Update History.

In this Newsletter

Retain Pro 2007 users

This version is now nearly four years old and has been replaced by Retain Pro 9 which has been code-updated and has many improvements and new features. We will be discontinuing support for this version on September 15th and due to changing to a simpler installation system it will be difficult to assist with any unresolved installation problems. If you have not upgraded we still offer the upgrade for $99 until September 15th. Thereafter, upgrading will still be available for $195.

Does your building department have Retain Pro?

Currently over 300 city, county, state, and federal agencies use Retain Pro - most for plan checking. We offer a free Retain Pro 9 to any city, county, state, or federal agency using it for design reviews (no commercial use). If your building official or design review agency would like a copy, they can submit their request by clicking a tab on the Order Menu at This will help them review your design submittals -- and those submitted by others - and gives you one-up for acceptance of your submittal. Alert them to take advantage of this offer!

Retain Pro Annual User Survey

Thanks to those of you who took our annual user survey which was attached to the spring Newsletter. We learned much about you. Some results from those responding:

General Questions:

62%Are one or two-person offices (non-engineering staff excluded) and 86% have fewer than 10 technical employees.
65%Design more than 12 retaining walls per year.
95%Report no unresolved issues from tech support.
100%Report little or no problem with building department acceptance.
73%Also use Enercalc software
76%Upgraded from an earlier version


81%Report little or no difficulty with installation
14%Some difficulty with installation
5%Needed help with installation

Features most used, in order:

- Cantilevered walls
- Restrained walls
- Seismic design
- Pier foundations
- Segmental retaining walls
- Gravity walls

How you rated Retain Pro 9:

84%Excellent or Very Good

Your company and the economy

Would you like to know how your peers are doing in this difficult economy? To find out, click on September Economy Survey on our home page. We refresh it every month. Click your answer to four choices and Submit, then View Results to see totals. We encourage participation because very few responded to our August survey and results can be interesting. Of those few who responded in August, the responses were:

20%We're busy
47%Hanging in
Post your current outlook on our home page!

You report it; we'll fix it.

Nearly all reports of glitches turn out to be misunderstandings of the program or erroneous entries. However, sometimes an astute user does find a problem needing fixing. We appreciate being alerted and fix it as soon as possible with an update release. But we do ask that you be as specific as you can to help us validate. Several years ago a user simply emailed "There's a bug in your program". But that's life in tech support :).

Have A Kindle?

Our book Basics of Retaining Wall Design, 8th Edition, is selling well on Amazon (and from our website) and we are working with Amazon to have it offered in a Kindle version. Keyword: "Retaining wall design".

Technical Topics

Before emailing your questions, check Tech FAQs. On our Support page ( The most common questions we get are at the top of the list. You can save yourself (and us) time and get faster answers.

If you receive the Access Denied message, this is a Windows 7 and Vista security feature that prevents unauthorized employees to access Retain Pro. It's very easy to grant yourself the rights and eliminate this message. Here are the instructions:

Lap splices for masonry (ASD) are 40 and 48 bar diameters respectively for Grade 40 and Grade 60 reinforcing bars.. See IBC '08, Section 2107.3 which modifies the requirements in MSJC '08 Section And note that the foregoing IBC section also requires the splice lap to be increased 50% when tension in rebar exceeds 80% of allowable.

Seismic force for self-weight on cantilevered and restrained walls is 0.4 SDS per ASCE 7-10, section 12.11.1. This is the Fp / Wp factor to be used in Retain Pro (Loads>Seismic).

Transferring prior version project (.rp5 files) and walls to Retain Pro 9. Instructions for doing this are on Tech FAQs at

Selecting the kh value for seismic design. Retain Pro 9 uses the Mononobe-Okabe equation to determine combined static and dynamic forces. The M-O equation is a modification of the familiar Coulomb equation - if there is no acceleration it becomes the Coulomb equation. First, determine SDS per IBC '09, Section 1615.5. Then for peak ground acceleration for retaining walls see Section 1803.5.12(2) and ASCE 7-05, 11.8.3(2) which defines the design acceleration as SDS/2,5. The kh design value is the same as further described in NEHRP (FEMA) Commentary, Section 7.5.1 defining kh = SDS/2.5. This is the value to insert for seismic due to soil pressure. Retain Pro converts this to an angle (Θ = tan-1 kh) for use in the Mononobe-Okabe equation. This procedure is NOT applicable for restrained walls - refer to the above cited NEHRP section or our companion book Basics of Retaining Wall Design.

Seismic design criteria recommended in geotechnical reports often specifies a lateral seismic pressure multiplier to the soil density, usually expressed as, for example, 20H, where H is the retained height. It usually specifies it as a uniform load with the point of application at 0.6H. which actually results in a slightly trapezoidal loading diagram. Retain Pro 9 offers this option which we call the "simplified procedure". The geotechnical consultant presumably obtains this multiplier using the Mononobe-Okabe (M-O) equation, first calculating (KAE - KA), from which the multiplier to "H" can be shown to be [ 0.5*(soil density)*(KAE - KA)]. They present it in this form to (presumably) save you time calculating the M-O equation. However, Retain Pro 9 users can do this themselves by just calculating kh (= SDS/2.5) and inserting it on the Loads>Seismic screen. The program does the rest.

Did we not respond to your email? If we do not respond within two business days please resend - some emails are inadvertently overlooked, for which we apologize.

Segmental retaining walls (SRWs)

This is becoming an increasingly popular feature in Retain Pro. Vendor data has been updated in release 9.13. If you have contact with any vendor who would like to be included ask them to contact us. All we need is their permission, any comments they wish to make, and their ES-ICC Evaluation Report (see which gives block descriptions, test results, geogrid data if applicable, and related information. Currently their listing is free.

We're looking for a backup structural consultant

We use several independent consultants to assist us in feature checking and tech support for some of Retain Pro's modules (segmental walls and geotechnical issues, for example). If you know of a licensed civil or structural engineer familiar with Retain Pro and well versed in concrete and masonry design, and building codes, who would like to assist us on a part time consulting basis, he or she can contact me at for more details.

Suggestions and comments.

Send them to me at

With best wishes,


Hugh Brooks, SE
Retain Pro Software

Retain Pro 2007 users: The $99 upgrade offer, and support for this version, ends September 15th.
If you're still using Retain Pro 2007 upgrade now at

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 and on the subject line type "Cancel", and don't forget to include your company name and email address where you received this.

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