I have used the design response spectrum in ASCE 7 for seismic analysis but I'm certainly not an expert in seismic analysis. The newest version of the UFC 3-310-04 military specification has a risk category V which states the structure must perform elastically during a seismic event. It also states the “Site Specific Ground Motion Procedures outlined in ASCE 7-10 Section 11.4.7 shall be used to develop MCE[sub]R[/sub] ground motion acceleration time histories for RC V structures”. Does this mean the structure must be designed using a time history of acceleration forces applied to the structure base instead of the lateral force method? I may not have stated that correctly but I think the meaning is clear enough. I'm not qualified to design a structure using that method, I just need to know if that method is required.