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In this paper the effectiveness of the application of a hemp biocomposite reinforcement at the extrados of a masonry barrel vault was investigated. To this aim, two specimens of unreinforced (UV) and reinforced (RV) masonry vaults were built having the same geometry with brickwork material and subjected to shaking table seismic tests. The comparison of the dynamic behavior between the two specimens was carried out by increasing the intensity of the seismic input, which was simultaneously applied on both the structures. The evaluation of the progressive damage induced by the seismic input was observed by visual inspections and natural frequencies decay estimated by experimental dynamic identification through the application of Operational Modal Analysis (OMA) techniques.

Recently, the field of earthquake engineering experienced substantial enhancements due to numerous results of experimental and theoretical researches. Modern technical codes recognized the last advances in this field and provided new solutions for the structural assessment and design of buildings. However, the need for large scale testing is still taking several open questions, especially for the design of civil infrastructures, and experimental activity on full scale specimens has become necessary. This paper presents the main testing facilities of a new research centre, namely the Laboratory of Earthquake engineering and Dynamic Analysis (LEDA) of the University of Enna “Kore”. In particular, the design procedures of facilities for dynamic and pseudo-dynamic testing, built in order to perform tests on specimens of large dimensions, are described and discussed. The LEDA centre, includes several laboratories operating in the fields of structural engineering and dynamics. The most important features of LEDA are the broad band of tests that can be performed and the presence of a high capacity strong floor - reaction wall system and of two six-degrees-of-freedom shaking tables. The capabilities of the laboratory are highlighted, stressing as the complementarity of both traditional techniques (pseudo-dynamic and dynamic tests) can be fully studied and advanced hybrid testing method can be investigated.

Cultural heritage is the set of things, that having particular historical cultural and aesthetic are of public interest and constitute the wealth and civilization of a place and its people. Sharpen up methodologies aimed at safeguarding of monuments is crucial because the future may have in mind the historical past. Italy is a country that has invested heavily on its historical memory returned in large part by the historical building or the monuments. Furthermore, culture represents a fundamental indicator of the growth of the culture of a country. Consider a monitoring project of one of the most Impressive theater in the world, like “Teatro Massimo” in Palermo (Italy), means to add value to both of the issues mentioned above. Among several methods providing useful information about the conservation status of the structures, dynamic monitoring techniques are suitable to check and restore the global behavior of the buildings. The anomalous features diagnosis of the structural dynamic response is an index of alterations of the material state and, in the worst cases, is related to the presence of damaged structural elements. The present paper assesses, through a real investigation, the importance of dynamic tests on historical buildings. In particular impulsive tests return the main structural characteristics describing the current behaviour. Such tests are then crucial for updating numerical evaluation and check the need of restoring original main features or not, suggesting a strategy of restoration as well.

In this paper a new model for the liquid motion within a Tuned Liquid Column Damper (TLCD) device is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it is shown that existing model does not always lead to accurate prediction of the liquid motion. A better model is then needed for accurate simulation of the behavior of TLCD systems. As regards, it has been demonstrated how correctly including the first linear liquid sloshing mode, through the equivalent mechanical analogy well established in literature, produces numerical results that highly match the corresponding experimental ones. Since the apparent effect of sloshing is the deviation of the natural frequency from the theoretical one, the authors propose a fractional differential equation of motion. The latter choice is supported by the fact that the introduction a fractional derivative of order α alters simultaneously both the resonant frequency and the degree of damping of the system. It will be shown, through an extensive experimental analysis, how the proposed model accurately describes liquid surface displacements.

Passive control devices are often added to slender and flexible systems in order to increase their structural safety. Several types of devices have been proposed in order to reduce the dynamic responses of different kind of structural systems. Among them, the tuned liquid column damper (TLCD) proved to be very effective in reducing vibration of various type of structures by means of a combined action which involves the motion of the liquid mass within the tube. The restoring force, in particular, is produced by the force of gravity acting on the liquid and the damping effect is generated by the hydrodynamic head losses that arise during the motion of the liquid inside the TLCD. Since the increasing use of TLCD in practical realizations, an approximated simplified formulation, by means of a statistical linearization technique has been previously developed by the same authors. This direct and ready-to-use formulation is able to predict the effectiveness of TLCD on a structure subjected to random loads and has been numerically validated by means of a parametric analysis in a stochastic framework by comparison with the numerical Monte Carlo simulation based on the nonlinear complete system for a wide range of the system parameters. In this paper optimal TLCD parameters have been computed taking advantage of the proposed approximated formulation, by which a smooth function, defining the main system variance, can be formulated and easily minimized, resulting in a significant reduction of the computational time and a valuable tool for design purposes. Moreover, starting from the proposed formulation, optimal design charts have been created which enable for an easy and quick evaluation of the TLCD parameters design.

The passive control of vibrations has received in recent years a great deal of attention from researchers. Several types of devices have been proposed in order to reduce the dynamic responses of different kinds of structural systems. Among them, the Tuned Liquid Column Damper (TLCD) has proved to be very effective in reducing vibration of structures. However, since the equations governing the TLCD controlled systems response is nonlinear, the calibration of TLCD parameters is time consuming and not convenient to perform in a pre-design phase. In this context, it has recently been introduced by the authors a formula that allows to choose the optimal parameters of TLCD in a direct and fast way. This ready-to-use and straightforward proposed formulation has been verified by comparison with the numerical Monte Carlo simulation based on the nonlinear complete system. In this paper numerical results obtained with the proposed formulation are validated through an experimental campaign on a small scale SDOF shear-type model, built in the Experimental Dynamic Laboratory of University of Palermo, and equipped with a TLCD excited at the base with random noises through a shaking table.

In this paper, a novel mathematical model for the Tuned Liquid Column Damper (TLCD) is presented. Taking advantages of fractional derivatives and related concepts, a new equation of motion of the liquid inside the TLCD is obtained. Experimental laboratory tests have been performed in order to validate the proposed linear fractional formulation. Comparison among experimental results, numerical obtained using the classical formulation and numerical with the new linear fractional formulation are reported. Results in frequency domain show how the new linear fractional formulation can predict the real behavior of such a passive vibration control system, more correctly than the classical mathematical model, widely used in literature.

Very recently the tuned liquid column damper (TLCD) is receiving an increasing interest from researchers concerned with vibration control, to be considered an alternative device with respect to the tuned mass damper (TMD), since the former has low cost, easy adjustment, flexible installation. However, in recent studies the authors [1] have pointed out that for TMD the analytical formulation provides results that are in good agreement with the experimental ones, while for TLCD it has been deducted that the analytical formulation needs further investigation. In fact using the classical formulation of the problem, numerical results are very different from the experimental results obtained by the authors using the facilities at the experimental dynamic laboratory of University of Palermo. In particular it has been shown that the total liquid length should be corrected in an effective one, but in a different way from what has been done in literature, where only the variation of section of the vessel has been taken into account. On the other hand, from experimental investigations it is seen that the liquid moves more in the central area of the tube and less in the area in contact with the side walls. This aspect plays a fundamental role for capturing the real performance of TLCD. In fact, being the TLCD a special type of auxiliary damping device which relies on the inertia of liquid column in a U-tube to counteract the forces acting on the structure, then it is necessary to identify the effective moving liquid mass. To aim at this, in this paper the authors differentiate the total liquid mass into a liquid dead mass and a liquid dynamic mass, then introducing these values into a properly modified mathematical formulation numerical results match the experimental ones for all tests.

Mitigation of structural damage due to earthquake ground motion may be performed by inserting dampers in the structure. In order to enhance the damping effect various toggle brace configurations have been recently proposed. In this paper these equipments are analyzed in detail and compared with a new one here proposed. The analysis is performed by taking into account the inherent nonlinearities of the damper by means of stochastic analysis and validated by using time histories of recorder accelerograms and by the stochastic analysis using spectrum consistent power spectral density.