Parametric Assessment of Strengthening Interventions on a Monitored Masonry Building After the 2016 Central Italy Earthquake

Abstract

The definition of proper intervention strategies for the selection of optimal (and minimum) interventions on exiting masonry buildings is a quite complex task. The choice has to take into account several aspects such as construction time, cost/benefit analysis, use of the building during the execution of interventions, resilience of the structure in case of exceptional events. Moreover, it is necessary to study the effectiveness of interventions to guarantee adequate safety levels as well as the reliability of numerical tools for structural analysis and design. In this framework the research activities presented here aim at assessing the effectiveness of strengthening interventions executed on an unreinforced masonry building hit by the Central Italy earthquake swarm of 2016 (max Mw=6,5). The structure, constructed in 1940, is equipped with a dynamic monitoring system, managed by the Seismic Observatory of Structures (OSS) of the Italian Department of Civil Protection (DPC), that was able to record the dynamic response during each seismic sequence. Ambient vibrations and strong motion data were used to calibrate and validate numerical models, built with the equivalent frame approach using 3Muri software. Then parametric nonlinear static analyses on the calibrated models were implemented in order to assess the effectiveness of interventions performed on vertical and horizontal structural elements. The incremental application of interventions was also evaluated, and various strengthening technique tested, comparing the response in terms of structural performance and seismic capacity.

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

“…The UR of Pavia adopted the macroelement mechanical model presented in [25], [26] (named macroelement in Figure 11.d,e). The latter reproduces the cyclic nonlinear behavior associated with the two main in-plane masonry failure modes, bending-rocking and shear mechanisms, by means of a limited number of degrees of freedom (8) and internal variables describing the damage evolution ( Figure 11.d). Figures 11.e,f illustrate the cyclic behavior simulated by these two constitutive laws in the case of two panels characterized by a prevailing shear and flexural behavior, respectively.…”

“…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".…”

Analysis of the Recorded Response of a School Building Heavily Damaged by the 2016 Central Italy Earthquake

“…Several papers have been devoted to the analysis of the structural response and damage observed during the 2016 seismic sequence [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. They used different computational models and tools (commercial or research codes) based on a wide variety of approaches, including nonlinear, linear with kinematic constraints, non-smooth contact dynamics, macroelements, and seismic regulations codified procedures.…”

“…One group [4][5][6][7][8][9][10][11] is devoted to non-monitored structures; they are limited to a prediction of structure response and have highlighted the capacity of the computational techniques adopted in satisfactorily representing the real damage scenario, even if from a qualitative point of view. More interesting is the second group [12][13][14][15][16][17][18][19][20][21], which is devoted to the analysis of monitored structures, some of which are included in the OSS set. For these structures, as the one studied in this paper, records of dynamic quantities due to environmental and seismic excitations are available.…”