Understanding the concepts on Degrees of Freedom
Aim:-
To calculate the effective modal mass Mn* and the modal mass participating ratio for the 5 modes. The mass matrix will be required to evaluate these parameters.
After effective modal mass calculation, we have to calculate the base shear for each of the 5 modes of vibration and the combined base shear as per SRSS rule. The pseudo acceleration design spectrum to obtain the base shear for each mode is provided below.
after the above calculation, we have to show the modal mass participation factor to achieve a participating ratio of 90%.
PROCEDURE:-
Step:-1
To calculate the modal mass.
For Mode:-1
The mode of vibration (T1) = 2 seconds.
And its associated mode shape is shown below.
by using above formula
transpose mode shape is
ϕ1= [0.334 0.641 0.895 1.078 .173]
according to the above formula
