I´m trying to simulate a PSD (Random response) on a T-shaped beam in Abaqus.

From a previous modal analysis, i get the ressonant frequencies and corresponding mode shapes.

In the PSD Random response model, i'm simulating white noise: i created an amplitude with Real=1, Imaginary=0 for each frequency ranging from 1 to 100 in intervals of 1. I also specified gravity (base motion). In the boudary conditions, i,ve imposed an acceleration base motion, degree of freedom (U2) and in correlation defined: Approach: correlated, PSD: the Amplitude and Real= 1 & Imaginary=0

However, when i perform the PSD, looking to the acceleration vs. frequency plot, I,m only getting some of the modes that i found in the modal analysis...not all the modes. I talking about points in the beam where, according to the modal analysis, should have some vertical acceleration, but no ressonat frequency apears in the plot...

Does anyone had a similar problem?