On the Soil-Structure Interaction in the Seismic Response of a Monitored Masonry School Building Struck by the 2016-2017 Central Italy Earthquake

Abstract

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 soilfoundation 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.

Numerical simulation of the seismic response and soil–structure interaction for a monitored masonry school building damaged by the 2016 Central Italy earthquake

“…5.4. Furthermore, the reduction of experimental and numerical frequency in the quiet intervals between the couples of mainshocks (E1-E2 and E2-E3) as well as after mainshock E3 confirms the structural stiffness degradation related to damage accumulation and progression of nonlinear response (de Silva et al 2019). As a further corroboration of the relevance of soil-structure interaction, the degradation in the experimental frequency is better captured by the numerical CB model with respect to its FB counterpart.…”

Discussion on Data Recorded by the Italian Structural Seismic Monitoring Network on Three Masonry Structures Hit by the 2016-2017 Central Italy Earthquake

“…To date it has been demolished. The soil which the structure is built on is characterized by quite poor properties, as presented in [3], [4], [10] highlighting the possible role of soil-structure phenomena in the seismic response of the building as confirmed also by the identification of dynamic properties made by the Task 4.1 Workgroup [2] and other researcher through numerical studies [11]. To deepen the specific issue associated to the soil-structure interaction of Visso School, the geotechnical group coordinated by Prof. F.Silvestri from the University Federico II of Naples has been involved in the research activities of Task…”

“…In the following only a brief overview on the type of results achieved is presented while more detailed outcomes are illustrated in ([2], [3], [4] and [5]) for the Visso School and in [8] for the Fabriano Courthouse respectively. a.…”

“…This paper provides first of all an overview on the whole set of available data ( §2) and on the main features of each of the selected structures ( §3). Then, it briefly presents some results of the activities performed by each RU ( §4), starting from the data made available by OSS, which are more extensively described in ([2], [3], [4], [5], [17], [7], [8]). The main performed activities were: a) a detailed examination of the structural details and an accurate damage survey of each structure; b) the identification of the dynamic properties of the three selected structures, by using the records from both the main sequence of the Central Italy earthquake in 2016/2017, some minor events and ambient recordings; c) the calibration of different structural models that benefitted of such experimental periods and modal shapes; d) the execution of Non Linear Dynamic Analyses (NLDA) through these models to simulate the actual earthquake damage; e) the post-processing of recordings for confirming some evidences on the amplification phenomena provided by the filtering effect of the main structure to the seismic input and, as a consequence, for supporting the validation of expressions available in the literature for the so called "floor spectra".…”

Validation of a practice-oriented floor spectra formulation through actual data from the 2016/2017 Central Italy earthquake

“…For example, a study on instrumented buildings in California (USA) showed that the torsional responses of the supporting structure and/or the in-plane flexibility of floor diaphragms can increase by not negligible factors the seismic-induced force demands on elastic acceleration-sensitive non-structural components . Similarly, it is known that soil-structure interaction (SSI) can affect the acceleration response of the buildings (e,g, Karapetrou et al, 2015;Karatzetzou et al, 2015;de Silva et al, 2019;Fathi et al, 2020;Oz et al, 2020, Hamidia et al, 2021Brunelli et al, 2021).…”