Characteristics of the foundation ground of sites with severely damaged buildings in the 27F earthquake

Abstract

The Maule Earthquake affected a wide area of the country, being significantly destructive in the regions of Maule and Bío Bío. In the Metropolitan Region major damages were reported in both housings and modern buildings. In the case of buildings, failures ranged from minor damage to unrecoverable. To identify whether the ground was one of the triggering factors that damaged the buildings, environmental vibration measurements were carried out in the vicinity of severely damaged structures in the Province of Santiago. The analysis was performed using the method of Nakamura, which may provide the predominant period of the ground, especially in soils of low geotechnical quality, which present higher probability of generating structural damage in buildings. 122 measurements located in the vicinity of 68 severely damaged buildings located in the Province of Santiago were carried out. Also, the obtained spectral ratios H/V were compared with the geology of the area, in order to confirm the relationship between them. The analyses of the results indicate that there is no direct relationship between the observed damage of buildings and the seismic amplification, because the damaged buildings are located on different types of spectral ratio H/V. It is concluded that the main factor of the damages could be associated with structural aspects. In addition, the Santiago basin is subdivided into three sectors according to the H/Vspectral ratio (rigid, semi-rigid and predominant periods of 0.5 s).