Abstract
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.
Highlights
The evaluation of the dynamic behaviour of existing masonry buildings has received increasing attention in recent decades due to their unsatisfactory performances showed under seismic actions [1,2,3,4]
The authors carried out dynamic investigations using Operational Modal Analysis, OMA [29]
The first setup is used to characterize the global dynamics of the structure, while the second is used to identify with high accuracy the mode shapes characterized by a prevalent deformation of the floor
Summary
The evaluation of the dynamic behaviour of existing masonry buildings has received increasing attention in recent decades due to their unsatisfactory performances showed under seismic actions [1,2,3,4]. A significant proportion of the scientific literature about the dynamic behaviour of masonry buildings focuses on investigation of mechanical characteristics of vertical structures and horizontal ones, through experimental and numerical analysis, to grasp the main vulnerabilities of the built heritage. The main difficulties in estimating the dynamic response of masonry structures through OMA stand in the low-amplitude vibration in operational conditions and the presence of localized mode shapes. Localized mode shapes require installing an adequate number of sensors to achieve a fine discretization of the experimental mode shapes. These difficulties have determined more extensive applications of OMA in reinforced concrete (RC) and steel buildings compared to masonry ones. The application of OMA for the identification of the modal parameters of masonry structures as a practice-oriented non-destructive diagnosis technique is limited
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