Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Wind on Retaining Walls in IBC 2009 vs 2012

Wind on Retaining Walls in IBC 2009 vs 2012

Wind on Retaining Walls in IBC 2009 vs 2012

In section 1807.2.3 Safety factor the wording has not changed between the 2009 IBC and the 2012 IBC. It reads:

Retaining walls shall be designed to resist the lateral action of soil to produce sliding and over-turning with a minimum safety factor of 1.5 in each case. The load combinations of Section 1605 shall not apply to this requirement. Instead, design shall be based on 0.7 times nominal earthquake loads, 1.0 times other nominal loads, and investigation with one or more of the variable loads set to zero. The safety factor against lateral sliding shall be taken as the available soil resistance at the base of the retain...

In regards to wind loads:

In 2009 IBC the wind maps are Basic Wind speeds (example 90mph for a huge portion). At the bottom the notes say "these are nominal wind speeds"

In 2012 IBC the wind maps are Ultimate Wind speeds (example 115 mph for a huge portion). At the bottom of the map the notes also say "these are nominal wind speeds"

So why did the "Safety Factor" wording stay the same using "nominal" between 2009 IBC and 2012 IBC but the wind map wording "nominal" corresponds with the change between Basic and Ultimate wind speed (varying with safety factors)? Are "Other Nominal Loads" not including wind? What's the deal here?

RE: Wind on Retaining Walls in IBC 2009 vs 2012

I recall this being addressed in an errata or something. Short version is I recall the intent being retaining walls designed under ASD and thus the wind loads need to be reduced to ASD levels. In IBC 2012 there's an ASD conversion table in there for things like windows and such that require ASD level wind speed maps.

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA, FL) Structural Engineer (IL, HI)
American Concrete Industries https://americanconcrete.com/

RE: Wind on Retaining Walls in IBC 2009 vs 2012

I'm working thru validating our new retaining wall software and was just figuring out how they approach the sliding and OTM FS. Ultimately, if you input strength level wind loads, they are factored by 0.6 for service loads when computing the factors of safety and the actual soil pressures.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


eBook - Mastering Tolerances for Machined Parts
When making CNC machined parts, mastering tolerances can be challenging. Are general tolerances good enough? When does it make sense to call out for tighter tolerances? Do you need a better understanding of fits, datums, or GD&T? Learn about these topics and more in Xometry's new e-book. Download Now
eBook – How to Choose the Correct Corrosion Testing Method
When designing a metal component, engineers have to consider how susceptible certain alloys are to corrosion in the final product’s operating environment. In a recent study by NACE (National Association of Corrosion Engineers), it was estimated that the direct and indirect costs of corrosion in the United States is approximately 6.2% of the GDP. In 2016, that cost exceeded $1 trillion dollars for the first time. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close