Dynamic geotechnical testing and seismic response analysis at Fabriano, Italy

The Umbria-Marche earthquake occurred in September-October 1997 caused serious structural damages in the town of Fabriano (Ancona, Italy), especially in two residential zones, Borgo and Serraloggia-La Spina, located respectively north-west and south-east of the alluvial valley along which the built-up area lies. To evidence the influence of local soil conditions on possible ground motion amplification, detailed geotechnical investigations and numerical one-dimensional ground response analyses were carried out in the two sites. In particular, boreholes with undisturbed sampling, in laboratory geotechnical tests for measuring static and dynamic soil properties, and field geophysical tests to evaluate low-strain soil stiffness, were performed. Two time history accelerations, with a peak ground acceleration of 0.2g, were assumed as reference motions on rock for numerical modelling. They were obtained by a probabilistic-statistical seismic hazard analysis carried out in terms of response spectrum ordinates. The results of static and dynamic soil property measurements and of the ground response analyses carried out at the two sitesare presented in this paper.