Please always be as specific as possible - I am not sure if I understand what is your problem. As discussed in other threads, e.g.,
ATENA » Load case with constant vertical loads and changing horizontal loads
or
ATENA » Set the force as a function or ATENA » constant vertical load on masonry wall during horizontal displacment
or
ATENA » Set the force as a function,
all loads are incremental in ATENA.