×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

P-Delta in service loads

P-Delta in service loads

P-Delta in service loads

(OP)
I all,

I have a question about P-delta analysis.

I am doing a explicit second-order analysis in a steel structure (LRFD), and according AISC Design Guide 28, when performing a second-order analysis, the analysis must be conducted at the ultimate load level.

OK, I have to do it for every combination (i.g. 1.2DL +1.6LL).

But my question is for foundation design, soil capacity, overturning and sliding, i need service loads no ultimate loads.

In this case what can i do to have service loads including second-order loads?

Hope you can help me

Best regards,

RE: P-Delta in service loads

I wouldn't think P-delta effects would impact the soil capacity or overturning/sliding loads.

Maine EIT, Civil/Structural.

RE: P-Delta in service loads

(OP)
P-delta effects will increase the moment at the base (fixed base).

RE: P-Delta in service loads

Perhaps you could get the forces similar to how the direct analysis method can be used in ASD.

Factor your load for the load case and compare it to the unfactored equivalent load case. You should then be able to figure out a combined, overall factor by dividing the factored load by the unfactored load. Run your P-delta analysis using the factored loads and then divide your final elastic + p-delta combined load by the overall factor you figured earlier.

This should result in a unfactored load case that used the factored loads for the P-delta analysis.

Maine EIT, Civil/Structural.

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!


Resources