[en] Growing awareness of the negative effects due to ambient vibrations caused by transportations infrastructures in Historical centres is attributable to the high vulnerability of heritage buildings as a consequence of deterioration phenomena and damages that reduced the structural capacity of such valuable constructions over the past centuries. As the mobility demand increases, several cities hosting heritage buildings are subjected to raising traffic loadings, so that constructions of new infrastructures is often required. Hence, assessing the effects of short-term vibrations due to construction activities or the consequences of the long-term vibrations caused by traffic is very important for the preservation of cultural heritage. An operative approach for evaluating the effects of ambient vibrations based on experimental measurements is a useful tool when a new infrastructure is being built, and can support strategic decisions for the elaboration of transportation plans at the urban level. Therefore, an overview is here presented of existing studies, guidelines and codes that provide pertinent information on this topic. Of special importance is the analysis of existing proposed thresholds, i.e. limit values that, if compiled with, damage due to ambient vibrations is not likely to occur. On the basis of such overview, the selection of threshold values for the Flavian Amphitheater is discussed, along with current efforts towards a wireless dynamic monitoring of its dynamic response.

[en] The problem treated in this paper is the optimal electromechanical setting of energy harvesters working with vibrations of random nature. We consider a simple system composed of two parts; one electrical circuit with a mechanical single-degree-of-freedom system, coupled to a piezoelectric element. The electric circuit is modeled as a simple one, composed of a resistance and a capacity only, while a linear viscoelastic model is used for the mechanical element. The only joint electro and mechanical element is the piezoelectric device, which is controlled by both the mechanical velocity and the electrical tension. This scheme is treated as dimensionless using the random vibration theory since the base excitation is considered as a stationary white noise Gaussian process. To consider the non-uniform frequency content, that characterizes many real vibration phenomena, the input is properly colored using simple linear filters. System response statistics is evaluated by covariance approach, producing both covariance matrix of system parameters and mean value of electric power under different filters and systems configurations. The optimal ratio between the periods of the mechanical and electric systems is thus defined maximizing the mean power value. This ratio is obtained numerically for some test cases in a graphic representation to evaluate the sensitivity response to selected parameters. (paper)