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

ETABS: Automatic Live Load Reduction

ETABS: Automatic Live Load Reduction

ETABS: Automatic Live Load Reduction

Hi All,

I am modeling a sample project to understand how ETABS reduces the live load automatically.

I modeled the 10-storey building shown in the attached file by defining the live load pattern one time as (Live) and the other time as (Reducible Live) from "Define --> Load Patterns..."

I also chose the Canadian Building Code (NBCC2010) from "Design --> Live Load Reduction Factors... --> Tributary Area (Based on Design Code)".

I assumed that the live load on the slabs is 2.873 kPa and the span between each two adjacent columns is 6.0 m. Dead load is not considered in the analysis (Self-weight multiplier = 0).

Surprisingly, the results for both cases (live and reducible live) are the same! This means that ETABS did not reduce the live load as it should do.

Can anyone please help me with this issue? What should I do to let ETABS consider the live load reduction?

Thanks in advance!


RE: ETABS: Automatic Live Load Reduction

ETABS does not reduce live load until you run a design. If you're just looking at plain analysis results, your live load reduction won't be in there yet.

If you're looking at tables, the table that would have live load reduction incorporated is Tables>Design>Design Forces. It will also only give you results for load combinations that are designated for design, not individual load cases.

RE: ETABS: Automatic Live Load Reduction

Thank you MrHershey, you are right! I checked the design forces and they were reduced as expected. I made a quick comparison between ETABS results and manual calculations for the reduction factor:

Reduction Factors (ETABS):
Story 10: 0.832
Story 9: 0.683
Story 8: 0.613
Story 7: 0.571
Story 6: 0.542
Story 5: 0.520
Story 4: 0.503
Story 3: 0.488
Story 2: 0.476
Story 1: 0.466

Reduction Factors (Manual Calculations):
Story 10: 0.822
Story 9: 0.669
Story 8: 0.601
Story 7: 0.561
Story 6: 0.533
Story 5: 0.513
Story 4: 0.497
Story 3: 0.484
Story 2: 0.474
Story 1: 0.465

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! Already a Member? Login


White Paper - How ESI is Helping Move New Medical Device Product to Market Quicker & More Cost Effic
Early Supplier Involvement has long been a strategy employed by manufacturers to produce innovative products. Now, it almost seems like a necessity. Because decisions made in the design phase can positively affect product quality and costs, this can help add value to OEM bottom lines. This white paper will discuss many facets of ESI, including why it’s so valuable today, what challenges limit the benefits of ESI, how cost is impacted, and more. 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