Numerical Simulation of the Nonlinear Earthquake Response of a Monitored Urm School Building

Abstract

The seismic sequence that stroke central Italy in August and October 2016 affected a large number of school buildings. One of these was the elementary school of the town of Visso, a 5000-cubic-metre, two-storey stone masonry building. The Italian Structural Seismic Observatory (OSS), a network of permanent sensors mainly installed in public buildings by the Department of Civil Protection, monitored this school. Twenty-three accelerometric channels allowed recording the dynamic response of the building during the entire sequence, which caused the collapse of portions of masonry walls and floor diaphragms. Double-integration of acceleration time histories provided estimations of displacements and deformations, which can be related to different damage states. A detailed geometric and mechanical characterization of the structural system complemented the data provided by the OSS, allowing the development of a reliable equivalent-frame numerical model of the building, implemented in the software Tremuri. The comparison between data recorded on site and nonlinear time-history analysis results confirmed some of the main modelling assumptions typically validated against smaller shake table experiments.

Benchmarking the software packages to model and assess the seismic response of unreinforced masonry existing buildings through nonlinear static analyses

“…thanks to the dynamic parameters identified from ambient noise measurements and the acceleration recordings under the main mainshocks). Although the validation through an accurate calibration of the model (Ferrero et al 2020;Sivori et al 2021) or the simulation of the actual seismic response through more refined analyses, such as the nonlinear dynamic ones (Graziotti et al 2019;Brunelli et al 2021;Miraglia et al 2020), are out of the primary scopes of the "URM nonlinear modelling-Benchmark project", the availability of the dynamic properties and of an accurate reconstruction of the damage pattern allows to provide a first assessment of the reliability of the response predicted by commercial software packages.…”

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

“…The left part of Table 4 summarizes the experimental periods associated with the first three modes. The experimental periods appear to be significantly affected by the interaction with the soil being significantly higher than those expected for a URM building characterized by the structural details and the geometrical configuration of P.Capuzi school when assumed fixed at the base (as discussed for example in Graziotti et al 2019;Ferrero et al 2020). Figure 10 shows the natural periods identified from the ambient noise records compared to those resulting from modal analysis of both the FB and CB equivalent frame models .…”

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

“…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".…”