mass partition in modal analysis < 90%

mass partition in modal analysis < 90%

Anonymous
Not applicable
654 Views
7 Replies
Message 1 of 8

mass partition in modal analysis < 90%

Anonymous
Not applicable

hi everyone,
i model a industrial structure but the modal analysis only reaches a 73% of participation, can you give me any suggested to increase this valua to 90%

link of model: https://drive.google.com/file/d/1Fzakac2NLJbV2_1t5zLFhAb72FcIeqB3/view?usp=sharing  

0 Likes
655 Views
7 Replies
Replies (7)
Message 2 of 8

Romanich
Mentor
Mentor

Hi @Anonymous ,

Try this settings:

Romanich_0-1618377802596.png

 

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


0 Likes
Message 3 of 8

Anonymous
Not applicable

Hi @Romanich
if i use a mass matrix lumped then the total mass decreases from 236 (ton) to 178 (ton). If i keep a mass matrix lumped and add nodes in the concrete columns to increase the total mass the percent of participation modal decreases to approx 70%

0 Likes
Message 4 of 8

Simau
Mentor
Mentor

Hi @Anonymous 

Using this parameters you'll get 90%

90.png

M. Agayr
Did you find this post helpful? Feel free to Like this post.
Did your question get successfully answered? Then click on the ACCEPT SOLUTION button.

EESignature

0 Likes
Message 5 of 8

Anonymous
Not applicable

Hi @Simau 
Yes, but if i apply a mass matrix lumped without intermediate nodes, the mas of the analysis decreases a lot (the total weight of the structure is 243205 kg)
masa.PNG
and if i add nodes the weight is increased to 243205kg but the % decreases to 71%

0 Likes
Message 6 of 8

Simau
Mentor
Mentor

@Anonymous 

Mass are taken into account in nodes, so with columns we lose half of columns weight that goes tout support and then not taken into account.

So spliting your columns you'll get much total mass. (the much you split the higher mass you'll get)

Below spliting columns in 5 part you get

Split.png

Mass.png

 

M. Agayr
Did you find this post helpful? Feel free to Like this post.
Did your question get successfully answered? Then click on the ACCEPT SOLUTION button.

EESignature

0 Likes
Message 7 of 8

Simau
Mentor
Mentor

And if course you need to increase the number of mode in modal analysis to reach 90%.

M. Agayr
Did you find this post helpful? Feel free to Like this post.
Did your question get successfully answered? Then click on the ACCEPT SOLUTION button.

EESignature

0 Likes
Message 8 of 8

Anonymous
Not applicable

ok, my intention was to avoid increase the number of mode for the analysis time (136 mode)

0 Likes