×
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

no eigen vectors?

no eigen vectors?

no eigen vectors?

(OP)
I have warnings in my analysis log and modal analysis can not be performed.

-I tried removing all files except .edb
-I changed mass sources of the building in order to examine any change
-There is a sub-story between 2 stories. I have created it by using "move" command. It is something like +6.75 btw +4.5 and +9.00. Is it possible that ETABS can not see it as a mass source and breaks?
-I wish i could attach the docs but company does not allow.

Thank you.



Warnings:


 * * * W A R N I N G * * *
 SUBSPACE VECTORS ARE NOT INDEPENDENT,
 MODEL OF STRUCTURE MAY BE NUMERICALLY SENSITIVE,
 RE-RUN ANALYSIS WITH A DIFFERENT FREQUENCY SHIFT


 NUMBER OF EIGEN MODES FOUND               =           0
 NUMBER OF ITERATIONS PERFORMED            =           1

RE: no eigen vectors?

if there's problem in  eigenvector try the RITZ Vector it will run with more iteration than the eigen vector

in your mass source there are three type of loadings

1. from self and specified mass:only self weight will be a part of the base shear
2. from loads:from here you can compute the base shear, based on what will you prefer (like you can choose the dead plus the SDL plus the load or you can just prefer the SDL plus the live load)
3. From self and specified mass and loads:you can enter your additional load  (because the base shear will automatically add the self weight)

 

RE: no eigen vectors?

(OP)
jenofstructures thank you for your response but my actual problem is not "how to add mass sources to your structures"

Additionally, Ritz Vector is not working properly too.

RE: no eigen vectors?

are you trying to say that there's a mezzanine between those floors?

try to model it as a story too and not use the reference line on it

 

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