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This paper focuses on the dynamic behaviour of a low-rise masonry building representing the Italian residential heritage through experimental and numerical analyses. The authors discuss an application of combined Operational Modal Analysis and Finite Element Model updating for indirect estimation of the structural parameters. Two ambient vibration tests were carried out to estimate the structure’s dynamic behaviour in operational conditions. The first experimental setup consisted of accelerometers gathered in a row along the first floor to characterize the local dynamic of the floor. Conversely, the second setup had the accelerometers placed at the building’s corners to characterize the global dynamics. The outcomes of the first setup were used to estimate the mechanical parameters of the floor, while the ones form the second were used to characterize the mechanical parameters of the masonry piers. Therefore, two finite element models were implemented: (i) a single beam with an equivalent section of the floor to grasp the local behaviour of the investigated horizontal structure; (ii) an equivalent frame model of the entire building to characterise the global dynamic behaviour. The model updating process was developed in two phases to seize local and global dynamic responses. The updated numerical model formed the basis for a sensitivity analysis using the modelling parameters. The authors chose to delve into the influence of the floor on the dynamic behaviour of low-rise masonry buildings. With this aim, non-linear dynamic analyses were carried out under different mechanical characteristics of floors, expressing the scatter for ordinary masonry buildings. The displacements’ trends along the height of the building evidenced the notable role of the floor’s stiffness in the non-linear dynamic behaviour of the building. Lastly, the authors derived the fragility curves predicting the seismic performance in failure probability under a highly severe damage state.

Masonry towers, located in seismic zones, are vulnerable and prone to damages up to compromise their stability. The scatter of data on the mechanical properties of masonry, geometry and boundary conditions determine a lack of building knowledge on their expected behaviour. Therefore the assessment of the seismic capacity represents a critical task. This paper contributes to the issue of seismic analysis of masonry towers, focusing a meaningful case study: the St.Silvestro belfry in L’Aquila, Italy. The tower, severely damaged by the 2009 earthquake sequence, underwent extensive restoration works, endeavoured to mitigate its vulnerability. The observed seismic damage, the performed no-destructive testing campaign and the accomplished rehabilitation measures are described in the paper. The authors appraised the actual seismic performances of the St.Silvestro belfry, reinforced by the last restoration works. At first, the Operational Modal Analysis (OMA) is carried out to enhance building knowledge. In a second step, a refined finite element model is calibrated on the results from OMA to seize the actual dynamic response. Ultimately, by using the updated finite element model, the authors estimate the fragility curves in terms of peak ground acceleration using truncated incremental dynamic analyses.

The city of L’Aquila (Italy) includes a significant amount of masonry palaces erected from the middle of the 13th century up to the first half of the 20th century. This paper focuses on the seismic response of a masonry palace built during the first half of the 20th century and characterized by regularity in plan and elevation. The authors investigate the seismic response by varying a suite of modelling parameters that express the actual scatter of the mechanical properties typical of the masonry palaces erected in L’Aquila. The authors discuss the seismic performance exhibited by this building during the 2009 earthquake. Then, they assess the sensitivity of the selected building’s seismic performance via non-linear static analysis to the mechanical properties of masonry, the in-plane stiffness of the floors, and the mechanical resistance of the spandrels. The parametric analysis shows that the three variables markedly affect the shear resistance, the ultimate displacement, and the behavior factors. The fragility functions were then estimated from the results of non-linear static analysis. A significant scatter of the probability of collapse for the considered limit states reveals the limitations of typological approaches for masonry palaces.

The authors investigated the dynamic behaviour of the San Silvestro belfry in L’Aquila (Italy). The 2009 earthquake in L’Aquila caused severe damages to the entire masonry complex. Extensive rehabilitation works, ended in 2019, repaired the structure and enhanced its seismic safety. In this paper, the authors discuss three aspects typical of masonry towers by interpreting the outcomes of Operational Modal Analysis carried out on December 2019: the interactions between the tower and the masonry complex, the dynamic effects of the bell, and the seismic reliability assessment of the tower. Specifically, the experimental mode shapes drive the estimation of an equivalent cross-section, whose principal axes of inertia match with the directions of oscillation of the mode shapes, and the parameters of an equivalent cantilevered beam roughly representative of the tower dynamics. In a second step, a two-degrees-of-freedom analytical model simulates the dynamic coupling between the tower and the more massive bell. The response of the system to a set of seven strong-motion earthquakes yields the assessment of the bell effects over the seismic performance of the masonry tower.

The paper presents the experimental investigation carried out on wall specimens reproducing the ancient masonry of several monumental building located in the old city centre of L'Aquila (Italy) and damaged by the April 2009 earthquake. The wall specimens were prepared in accordance with the traditional technique, using original stone elements and typical poor mortar. Subsequently, the specimens were consolidated with mortar injections. Other specimens were also reinforced with Ultra High Tensile Strength Steel wires applied as coating technique (not wrapped). Shear-compression tests were carried out on the wall specimens to evaluate the effects of the reinforcements both in terms of final stiffness and strength of the specimens. A non-linear Finite Element Model (FEM) was developed to reproduce the experimental tests and to better understand the damage phenomena. The load-displacement curves predicted by the FEM compared quite well with the experimental ones. The failure mode of the specimens was properly captured by the FEM. The effectiveness of the external reinforcement was proved to strictly depend on the coating adhesiveness to the walls surface. The premature debonding of the external reinforcement was demonstrated to cause the fragile post-peak behaviour during both the actual experimental test and the numerical simulations.