mass for dynamic analysis

[wooj]

Hello,
I am performing dynamic analysis with 2d frame and i am a little bit confused about input mass. I have 3d frame dynamic test results and the frame is the (2d frame x 2bay x 1 story) with 20 tons on the top. For the dynamic analysis with 2d frame model to get same responses from the test, do i have to put 20tons as input mass or 10tons because 2d model is a half model of 3d frame?
Any opinion is welcome.
Thank you in advance.

[mhscott]

You have to figure out the tributary areas.

[wooj]

Thank you for your advice. i am wondering that m should be m/2 beacuse 1 story columns were 4 but the numerical model is only 2 which means k/2. But analysis result shows two results(disp, Tn, etc.) from test and anlaysis fit when input mass was m not m/2.