Reduction of seismic vulnerability by geomaterial attenuation procedures

Analytical and experimental studies in literature have shown that the liquefaction hazard of soft soil sites can be substantially reduced by ground improvement or replacement of the uppermost portion of a subsoil profile. The paper summarises the most recent advances in these studies, addressed to verify the applicability of the so-called Geomaterial Attenuation Procedure (GAP) to simplified subsoil patterns, characterised by different kinds of heterogeneity in terms of shear wave velocity profiles. Preliminary design criteria were first formulated, then summarised in synthetic charts, and finally tested on actual subsoil profiles subjected to strong-motion seismic shaking. The GAP demonstrated most effective in the range of natural periods pertaining to medium-height buildings, made by either masonry walls or r.c. frames.