Time and Spatially Varying Nodal Forces

[ybams]

Can someone give me an insight on how to apply a time and spatially varying nodal force on some sets of node using user subroutines?
Is there any subroutine for this,because Dload subroutine is only for uniformly distributed load.
The nodal forces are not known apriori but changes at each node location as the solution progresses
Thanks

 

[xerf]

Maybe
*cload, amplitude
where the amplitude is defined in UAMP subroutine? But I do not think it will work.

Btw, DLOAD subroutine is to specify NON-UNIFORMLY distributed loads.