Defining seismic mass (weight) of area/floor loads. IBC 2006

Hi

I am using IBC2006 on a project and have a newbie question

I have defined the seismic parameters and converted the nodal and member loads into *weights* to go with the selfweight that I need to. So how do I convert my floor/area loads into *weights* also needed for inclusion in the seismic mass?

 

I would appreciate anyone's help. Thanks