The mass model is created automatically in accordance with 12.7.2.

Live Load Reduction should be given from Story settings by users.

In case the structural system elements are modeled as beam, plate (membrane) or shell finite element, the individual node masses are assigned as the components of the distributed masses in the coverage areas of the connected finite elements. Singular masses at finite element nodes are defined to correspond to only two horizontal or additional vertical translation degrees of freedom. 

The effective seismic weight, W, of a structure includes dead load and live loads. In the story settings, LLR factor should be given by users. In default settings, it is arranged as 0.25.