Browsing by Author "Quattrone, Antonino"

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    Dynamic investigation on the Mirandola bell tower in post-earthquake scenarios
    (Springer , 2016-07-19) Zanotti Fragonara, Luca; Boscato, Giosue; Ceravolo, Rosario; Lentile, Silvia; Russo, Salvatore; Pecorelli, Marica Leonarda; Quattrone, Antonino
    After the seismic events of the 20th and 29th of May 2012 in Emilia (Italy), most of the monumental and historic buildings of the area were severely damaged. In a few structures, partial collapse mechanisms were observed (e.g. façade tilting, out-of-plane overturning of panels…). This paper presents the case-study of the bell tower of the Santa Maria Maggiore cathedral, located in Mirandola (Italy). The dynamic response of the structure was evaluated through operational modal analysis using ambient vibrations, a consolidated non-destructive procedure that estimates the dynamic parameters of the bell-tower. The dynamic tests were carried out in pre-intervention and post-intervention conditions in order to understand the sensitivity of dynamic measurements to safety interventions. Furthermore, a comparative study is made with similar cases of undamaged masonry towers up to the 6th mode. Finally, an investigation on the state of connections and of the building itself is carried out via FE model updating.
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    Experimental testing of a masonry arch bridge model subject to increasing level of damage
    (European Commission, 2011-01-31) Degiovanni, L.; Quattrone, Antonino; Zanotti Fragonara, Luca; Ceravolo, Rosario; De Stefano, Alessandro
    Masonry arch bridges are particularly sensitive to the bearings loss produced by scour of the streambed soil at the piers foundations. A 1:2 scaled experimental model of a masonry arch bridge was built to study the evolution of the damage mechanism related to the application of foundation movements. The model was built with handmade clay bricks and a mortar with poor mechanical properties in order to reproduce typical materials of historical constructions, and an extensive characterization of the materials has been carried out. The mid-span pier is placed on a settlement application system, expressly designed to simulate the scour effect, quantified through hydraulic flume tests performed on a further scaled down model. Damage levels of increasing intensity have been simulated through the application of pier settlements and rotations. Experimental vibration tests were performed on the undamaged structure and after each settlement step. Both the environmental noise and the impacts of a sledge hammer were used as excitation sources. A complete dynamic identification was carried out and the variation of modal parameters at different levels of damage monitored. Moreover, the use of a testing shaker allowed investigating the non - linear behaviour of the damaged model.
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    Model updating of strategic building structures under real earthquake loading
    (CRC Press, 2013-12-31) Ceravolo, Rosario; Matta, Emiliano; Quattrone, Antonino; Zanotti Fragonara, Luca; De Stefano, Alessandro
    Public buildings such as hospitals, schools, churches and city halls constitute an asset of strategic importance into the life of a community. The assessment of the safety conditions and the vulnerability to natural catastrophic events must be checked, also resorting to experimental techniques. The adoption of vibration monitoring procedures represents a particularly appealing perspective for existing structures. The growing use of permanent monitoring systems allows collecting data of the structural response during earthquakes. An invaluable tool for structural health monitoring and damage detection, parametric system identification through model-updating is an inverse problem, affected by several kinds of modelling assumptions and measurement errors. By minimizing the discrepancy between the measured data and the simulated response, traditional model-updating techniques identify one single optimal model that behaves similarly to the real structure.
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    Structural system identification in the presence of resonant non-structural appendages
    (Civil-Comp Press, 2012-12-31) Matta, Emiliano; Ceravolo, Rosario; De Stefano, Alessandro; Quattrone, Antonino; Zanotti Fragonara, Luca
    Accurate finite element (FE) models are required in many applications of civil engineering. Non-structural elements (NSEs) often interfere with the main structure, altering its stiffness and modal signature. Neglecting such interaction in modelling, although a common design practice, may lead to unreliable predictions of future events and biased interpretations of in-field dynamic tests. In the current literature, the role of NSEs in vibration-based structural system identification (SSI) is well documented for NSEs working in parallel (P-NSEs) with the main structure (e.g.masonry infills in buildings, pavements or railings in bridges and footbridges) but is totally unexplored for NSEs working in series (S-NSEs) with the main structure (e.g. non-structural appendages such as chimneys, parapets, tanks, but also partitions and claddings in their out-of-plane modes). Presenting various numerical and experimental case studies, the present paper shows how in-series NSEs, through augmenting the modal model and by chance resonating with some structural mode, might significantly alter the dynamic behaviour of the main structure, and severely invalidate SSI if not properly accounted for while performing modelling and dynamic identification.
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    Tuned mass dampers for the mitigation of impulsive ground motions
    (Civil-Comp Press, 2012-12-01) Matta, Emiliano; Ceravolo, Rosario; De Stefano, Alessandro; Quattrone, Antonino; Zanotti Fragonara, Luca
    The performance of tuned mass dampers (TMDs) diminishes as the input duration shortens. As a result, they are not recommended for use against short-duration, pulse-like ground motions, such as those occurring in near-field (NF) zones in the presence of forward-directivity or fling-step effects. Yet a systematic assessment of this control loss is still missing. In this paper, a recent analytical model of ground motion pulses is applied to the design and evaluation of TMDs against impulsive earthquakes. Based on this model, first a new optimization method is introduced as an alternative to the classical H∞ approach. Then the two strategies are tested on single- and multi- degrees-of-freedom linear structures subject both to analytical pulses and to a large set of NF records possessing pulse-like features. The resulting statistical evaluation, expressed by percentile response spectra, shows the advantages and disadvantages of a pulse-oriented TMD design, and improves the general understanding of TMDs effectiveness under impulsive ground motions.
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    Unscented kalman filter for the identification of passive control devices
    (Taylor & Francis, 2013-12-31) Ceravolo, Rosario; De Stefano, Alessandro; Matta, Emiliano; Quattrone, Antonino; Zanotti Fragonara, Luca
    The Unscented Kalman Filter (UKF) is a technique which allows dealing with nonlinear systems and it is able to handle any type of non-linearity. In detail, differently from Extended Kalman Filter (EKF), UKF does not require the computation of the Jacobian of the non-linear function. Estimation of parameters through the UKF approach is an indirect procedure, consisting of transforming the parameter estimation problem into a state estimation problem. This is done by augmenting the system state vector by artificially defining the unknown parameters as additional state variables. In the present study the UKF is proposed to the purpose of the nonlinear identification of rolling-pendulum tuned vibration absorbers.