On the soil-structure interaction in the seismic response of a monitored masonry school building struck by the 2016-2017 central Italy earthquake

The paper discusses the effects of Soil-Foundation-Structure (SFS) interaction on the seismic response of the “Pietro Capuzi” school in Visso, a village located in the Marche region (Italy) that was severely damaged by the 2016-2017 Central Italy seismic sequence. The school is a two-story masonry structure founded on simple enlargements of its loadbearing walls, which are only partially embedded in the alluvial loose soil of the Nera river. The structure was monitored as a strategic building by the Italian Seismic Observatory of Structures. The dynamic behavior of the school under both ambient noise and the recently occurred seismic events was interpreted and compared with numerical simulations. A 3D structural model of the school was realized according to the equivalent frame approach with addition of springs that simulate a compliant base. The spring stiffness, representing the real part of soil-foundation dynamic impedance, was calibrated on the soil shear modulus mobilized during the seismic excitation, inferred from the deconvolution up to the bedrock of the accelerogram recorded at the underground floor of the school. The amplitude of the acceleration and the evolution with time of the frequency resulted from the analyses of the compliant-base and fixed-base models under the three main events of the Central Italy earthquake were compared to the actual records.