modal mass participation result 2

[DENSAL55]

In the results table below, I find that for the first mode the value in Ux direction and Ry are very important nomaly only one value should be expressive.is this good result.



Mode Period UX UY UZ SumUX SumUY SumUZ RX RY RZ SumRX SumRY SumRZ
1 0,910045 75,2861 0,0007 0,0000 75,2861 0,0007 0,0000 0,0011 99,4974 0,0053 0,0011 99,4974 0,0053
2 0,430470 0,0016 72,1128 0,0000 75,2877 72,1135 0,0000 98,7345 0,0011 0,0815 98,7356 99,4985 0,0868
3 0,375553 0,0096 0,0385 0,0000 75,2972 72,1519 0,0000 0,0469 0,0081 70,9066 98,7825 99,5067 70,9934
4 0,197741 10,2317 0,0011 0,0000 85,5289 72,1530 0,0000 0,0016 0,1217 0,0081 98,7841 99,6284 71,0015
5 0,104799 0,0003 10,7728 0,0000 85,5292 82,9258 0,0000 0,7230 0,0000 2,8893 99,5071 99,6284 73,8908
6 0,088809 6,1742 0,0010 0,0000 91,7033 82,9268 0,0000 0,0001 0,2856 0,0017 99,5072 99,9140 73,8925
7 0,079276 0,0003 3,0483 0,0000 91,7037 85,9751 0,0000 0,2256 0,0001 11,7153 99,7327 99,9141 85,6078
8 0,059936 0,0001 0,1440 0,0000 91,7037 86,1191 0,0000 0,0062 0,0000 0,0271 99,7390 99,9141 85,6349
9 0,052271 3,3125 0,0002 0,0000 95,0162 86,1193 0,0000 0,0000 0,0421 0,0004 99,7390 99,9562 85,6353
10 0,048579 0,0004 4,7498 0,0000 95,0166 90,8691 0,0000 0,1507 0,0000 1,3878 99,8897 99,9562 87,0231
11 0,038883 4,8055 0,0002 0,0000 99,8220 90,8693 0,0000 0,0000 0,0434 0,0009 99,8897 99,9997 87,0241
12 0,036300 0,0003 2,2210 0,0000 99,8224 93,0904 0,0000 0,0687 0,0000 4,5193 99,9584 99,9997 91,5434

 

[Murali27]

Absolutely good result, With the inclusion of 12 modes, modal mass participation achieved more than 90% in two translation & rotation degrees of freedom.

-Murali

 

[DENSAL55]

Thanks

 

[DENSAL55]

My question is "is it normal to find in the same mode two values with high ratio, in my case for the first mode i have
- Ux 75,2861
- Ry 99,4974 ."

thanks.

 

[WillisV]

That just means the first fundamental period of the building is a combined translational/torsional mode. It is not necessarily normal or not normal - it just depends on the layout of the lateral system in the building versus the mass distribution. You will want to make sure to design for any torsional irregularities per code.

 

[DENSAL55]

Thanks Willis

 

[Murali27]

Hi DENSAL55

As per your results, the modes are really uncoupled. i.e the first mode Ux = 75% & Ry (Over turning moment about y-y axis = 99.4%), Second mode Uy = 72.11% & Rx(Over turning moment about x-x axis = 98.75%) & Third mode Rz = 71% (Torsion mode)

Hope you understand.

 

[DENSAL55]

Thanks Murali27

 

[dawn836]

Murali27, what uncoupled modes mean?