Relation between dynamic amplification, structural height and damage in buildings affected by the recent Italian earthquakes

To exploit the purely geometric link between the elastic period of vibration T and the height H (or number of stories) of a building, T was varied from 0 to 0.5 s coinciding with a height between 0 and 12 m (at most the four stories typical of Italian buildings) in order to estimate the spectral accelerations corresponding to acceleration measurements recorded during the earthquakes of L’Aquila, Emilia and central Italy. These estimates were used to calculate the maximum dynamic amplification factors and corresponding heights, called critical heights, that can generate either resonance or appreciable dynamic amplification values. The results showed dynamic amplification values close to 3 for reinforced concrete buildings and 2.5 for masonry buildings independently of the characteristics of the earthquakes. There was a significant coincidence between the structural height of the buildings with greatest recorded damage and the critical height. The basis of the study lies in simple numerical steps carried out with easily obtainable data: for this reason, it can be easily applied to determine the vulnerability of a building according to its structural height.