Small Amplitude Vibration Measurements of Buildings Undamaged, Damaged, and Repaired after Earthquakes

Abstract

Ambient vibrations provided the means to measure dynamic properties of reinforced concrete undamaged buildings, damaged and repaired after the destructive earthquakes of February 24, 1981, in the major area of Athens and in Central Greece. Each fundamental period is given as function of the number of stories, the height of the building, the dimensions of its plan and the percentage of shear walls. The shape of the deformation of the vertical centerline and the associated percentage of critical damping resulted also from the measurements, which in addition proved that for the damaged buildings the vertical centerline presents a discontinuity at the level where the damages are concentrated. For the repaired buildings this line becomes smooth.