Static displacement in dynamic analysis

Hello everyone,

I am doing the calibration of my model with the appendix B of the IAFP-07 ( Spanish Normative of Train Bridges) . The model represents a simple beam with a mobile point load, the problem is that in the start of the analysis I have displacements in the opposite direction of gravity. Also when I do the FFT of the time history of displacements for the center node, it is evident that there is a static displacement present at the start of the analysis.

I try to follow the rolling stock example, but it also has an static displacement at the beginning of the analysis. I realize this when I do an FFT for a displacement history with a specific velocity.

So my question is: Is there a way to tell the software (Teddy) to avoid converting mass to load at the beginning of the dynamic analysis? So in that way I can eliminate the static displacement.

Thanks for the help!

PS. I attach the Teddy code and the pictures of the FFT.

SimpleBeam_PointLoad_v01.dat (3.0 KB)

this is the first impulse of the load. You can make simple test and reduce the load of load case 9001 to 10 kN, 1 kN, 0.1 kN or lower, then nothing happens any more. So the behaviour is only from the first impulse onto the system.
I hope this helps.

Best regards,