I’m trying to find natural period of structures constructed with beam and shell elements.
Sweeping test which applies sinusoidal waves with increasing frequencies is planned but I can’t find any way to apply (displacement, velocity, acceleration) histories to the structural nodes.
I have resolved the problem by my self. 
The sweeping test can be performed by either displacement or force control.
So, force histories could be applied to the structural node.
For Shell elements, we can not get acceleration histories, but for beam and pile elements, actually, we can obtain them through “struct node history name “acc-x” acceleration-x position (0,0,0).”
I tried it, and I got the histories. You can try it and see if it works for you. (FLAC 3D- 7.0)