building is concrete moment frame and symmetric .The model structure was displaced (pulled back) by 2mm at the second floor level using a steel wire. The wire was then suddenly released and the structure was allowed to vibrate freely. Acceleration and displacements were measured at each floor...
i have a real building model (two story) and i do a free vibration test for the building (floors acceleration had been measured)then i get the frequency for the first and second mode. what shall i do to calculate stiffness of the building?