Hi

my question is with regards a simple vertical cantilever model that I made in CII and the impact of a short term dynamic force on the bottom anchor of it.

I defined a "triangle" force-time spectrum and had CII convert it to a frequency-DLF spectrum and applied it in the middle of the cantilever. the largest contribution of the force is in the 4th mode of the system (4 X(1)) where the natural frequency is about 57HZ.
as I refer to the frequency-DLF spectrum, the DLF should be about 1.2 at about the same frequency.
to my surprise, the reaction force on the anchor is even smaller than one time the original applying force while I expected it to be 1.2 times of it according to the frequency-DLF spectrum.

can anyone explain what I am missing here please?

many thanks in advacne