Dear Sir, Thank you for reply. As i already mentioned about these perticular video in my question itself that i did follow guidelines given. As per the video we have extract the modes till we the ratio of effective mass to total mass equals to 90%. But in my even if i am extracting more number of modes my ratio is not going more than 50% for one perticular direction . As in video it is suggested to use residual vector or missing mass method (this method is not explained how to do in video) but this is applicable for Response Spectrum or Transient dynamic but i am performing MSUP Random Vibration analysis so that is why I am asking what i can do for this situation.