A monitoring system for monitoring a structure

Abstract

A monitoring system (1 ) for monitoring a structure, in particular said structure being the structure (20) of a building, a bridge, or another structure, comprises one or more data loggers (3) and one or more, in particular a plurality of, accelerometric sensors (2) connected to said one or more data loggers (3); one or more, in particular each, of said one or more accelerometric sensors (2) is a variable configuration accelerometric sensor. One or more, in particular each of the one or more accelerometric sensors (2) is a variable configuration accelerometric sensor such that said accelerometric sensor (2), during the operational life of said monitoring system (1 ), works at least in a first working condition and in a second working condition. The monitoring system (1 ) is continuously operating.

Description

[0001] DESCRIPTION

[0002] A MONITORING SYSTEM FOR MONITORING A STRUCTURE.

[0003] Field of application of the present invention

[0004] The present invention relates to a monitoring system for monitoring a structure, in particular which can be used for monitoring structures and works related to civil engineering, such as, for example, buildings, bridges, viaducts, or others.

[0005] It is understood that the present invention can also be used in other fields, such as, for example, the field of mechanical constructions.

[0006] State of the art

[0007] Monitoring systems with continuous operation are available on the market, comprising one or more accelerometric sensors (or accelerometers) connected to a data logger (“logger of data” - a unit for data collection and processing) used to detect the accelerations due to dynamic actions, such as seismic events or impacts.

[0008] Moreover, monitoring systems with continuous operation are available on the market, comprising one or more sensors, in particular accelerometric sensors, and at least one data logger, aimed at providing data concerning structural health monitoring (monitoring of the “health” of a structure), denoted as “SHM”.

[0009] In the above-mentioned monitoring systems, the accelerometric sensors are connected to a data logger (or to data loggers) by means of cables or wireless technologies.

[0010] It is now considered a continuously operating monitoring system installed on a given structure, adapted to detect the response of the structure itself when subjected to a seismic action. Such monitoring systems often operate according to a mode that can be identified as a “threshold mode”. The above-mentioned monitoring system measures the accelerations of the monitored points of the structure which, if exceeding preset threshold values due to an event (for example, a seismic event), are stored in the monitoring system itself; additionally, often, the monitoring system transmits to a server the measurements relating to the events during which the above- mentioned preset threshold values are exceeded.

[0011] From the knowledge of such accelerations, through specific processing, it is then possible to obtain information regarding the response of the monitored structure to the above-mentioned event.

[0012] According to the prior art, monitoring systems comprising accelerometric sensors and a data logger are also available on the market, which are used to perform OMA analyses (OMA stands for Operational Modal Analysis). Such accelerometric sensors are generally characterized, among other features, by very low noise, in particular by a very small spectral noise density, and by a sampling frequency which, as a rule, is lower than that of the accelerometric sensors used for detecting the accelerations due to seismic events; such monitoring systems are often installed on infrastructural works, such as bridges and viaducts.

[0013] Through the OMA analyses, in the presence of suitable environmental stresses, such as (for example) wind or road traffic, it is possible, by means of suitable algorithms, to perform the dynamic identification of the monitored structure, determining the values of its natural frequencies, damping values, and modal shapes of the structure itself. The results of a generic OMA analysis are associated with the “situation” of the monitored structure in the time interval during which the accelerometric sensors performed the measurements, providing a sort of “identity card” of the structure in the above- mentioned time interval. By periodically performing OMA analyses using the above-mentioned monitoring system, it is possible to identify any differences between the “situations” of the structure and to obtain information on possible damage and / or degradation phenomena suffered by the same structure during its service life.

[0014] The two types of monitoring systems described above, the first being adapted to obtain the response of the structure to a significant dynamic action, in particular to a seismic action, and the second being adapted to obtain the dynamic identification of the structure at various time instants over time, are characterized by differences, even though, as a rule, both use accelerometric sensors. The accelerometric sensors used to determine the response of the structure to dynamic actions (such as seismic actions and impacts) are characterized by a high sampling frequency, sufficient to allow detection even of the details of the dynamic actions themselves.

[0015] The accelerometric sensors used to provide data concerning SHM are characterized by a low sampling frequency and by a small value of spectral noise density.

[0016] In the prior art, monitoring systems are also known that use accelerometric sensors all of the same type, so that they can be used both to detect the effects on the monitored structure of dynamic actions and to carry out investigations within the scope of SHM. Such monitoring systems have the drawback that they are not optimized for monitoring the response of the monitored structure to dynamic actions, in particular to certain dynamic actions, such as impacts, and are not optimized to carry out investigations within the scope of SHM.

[0017] In cases where it is intended to continuously monitor a construction or a work, in particular an infrastructural work, both to obtain data concerning SHM and to obtain data concerning the response to a significant dynamic action, in practice, to optimize the obtained data, it is necessary to have two separate monitoring systems.

[0018] Summary of the invention In any case, the present invention aims to propose a new and / or alternative solution to those known so far, and in particular seeks to overcome one or more of the above-mentioned drawbacks or problems, and / or to satisfy one or more needs recognized in the art, in particular as evidenced by the foregoing.

[0019] Therefore, a monitoring system is provided for monitoring a structure, in particular said structure being the structure of a building, a bridge, or another structure; said monitoring system is characterized in that it comprises one or more data loggers and one or more, in particular a plurality of, accelerometric sensors connected to said one or more data logger; one or more, in particular each, of said one or more accelerometric sensors is a variable configuration accelerometric sensor.

[0020] Thus, it is possible, by a single monitoring system, to obtain measurements having optimal characteristics in terms of sampling frequency and filters used for signal processing, both for detecting the response of the structure to a dynamic action and for obtaining the data necessary for the dynamic identification of the structure itself.

[0021] Moreover, it is thus possible, by using a single continuously operating monitoring system, to obtain indications regarding the situation of the structure immediately after a seismic event, since it is possible to compare the data provided by the monitoring system after the seismic event with those provided by the same monitoring system before the seismic event, in order to identify possible damage to the structure caused by the above-mentioned seismic event.

[0022] Brief description of the drawings

[0023] This and other novel aspects are in any case set forth in the appended claims, the technical features of which can be identified, together with the corresponding advantages achieved, in the present detailed description, which illustrates merely exemplary, non-limiting embodiments of the present invention and is set forth with reference to the accompanying drawings, in which:

[0024] Fig. 1 schematically illustrates, according to an axonometric view, a monitoring system according to a first preferred embodiment of the present invention, installed at the structure of a building;

[0025] Fig. 2 schematically illustrates, in a larger scale than that of Fig. 1 , a detail of Fig. 1 ;

[0026] Fig. 3 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 1 ;

[0027] Fig. 4 schematically illustrates the monitoring system depicted in Fig. 1 operating in accordance with a specific operating procedure;

[0028] Fig. 5 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 4;

[0029] Fig. 6 schematically illustrates, according to an axonometric view, a monitoring system according to an implementation variation of the first preferred embodiment, installed at the structure of the building illustrated in Fig. 1 ;

[0030] Fig. 7 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 6;

[0031] Fig. 8 schematically illustrates the monitoring system depicted in Fig. 6 operating in accordance with a specific operating procedure;

[0032] Fig. 9 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 8;

[0033] Fig. 10 schematically illustrates, according to an axonometric view, a monitoring system in accordance with a second preferred embodiment of the present invention installed at a bridge;

[0034] Fig. 11 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 10; Fig. 12 schematically illustrates the monitoring system depicted in Fig. 10 operating in accordance with a specific operating procedure;

[0035] Fig. 13 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 12;

[0036] Fig. 14 schematically illustrates, according to an axonometric view, a monitoring system in accordance with a third preferred embodiment of the present invention installed at the structures of an industrial complex;

[0037] Fig. 15 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 14;

[0038] Fig. 16 schematically illustrates the monitoring system depicted in Fig. 14 operating in accordance with a specific operating procedure;

[0039] Fig. 17 schematically illustrates the block diagram of the monitoring system illustrated in Fig. 16.

[0040] Detailed description of preferred embodiments of the invention

[0041] With reference to the Figs. 1 to 5, a first preferred embodiment of a monitoring system 1 according to the present invention is illustrated. The monitoring system 1 is installed at the structure 20 of a building for offices. The structure 20 is made of reinforced concrete and comprises, in addition to columns, beams, and shear walls, floor slabs 21 and the foundation 22. In more detail, the structure 20 comprises seven floor slabs 21 (including the cover slab).

[0042] The monitoring system 1 is continuously operating and comprises a plurality of accelerometric sensors 2, according to the present first preferred embodiment, comprises twenty accelerometric sensors 2, a data logger 3, a cable 4 connecting the data logger 3 to the accelerometric sensors 2, a modem 7 for the Internet connection (external to the data logger 3) connected to the same data logger 3 by a connecting cable 8, and a power supply unit 5 also comprising an uninterruptible power supply; such power supply unit 5 is connected via a cable 11 the public low-voltage power grid. To the power supply unit 5 are connected, by means of two cables 6 (for electric power supply), the data logger 3 and the modem 7. The modem 7, for the Internet connection, is a GSM (Global System for Mobile Communications) modem. The data logger 3, via the cable 4, also provides the accelerometric sensors 2 with the electric power required for their operation.

[0043] The supply unit 5, the data logger 3, the modem 7 and other electrical equipment required for the operation of the monitoring system 1 (not illustrated in the Figures) are located inside a cabinet 10 arranged at the ground floor, at the first floor slab 21 , in an easily accessible position. In the Figures, only the data logger 3, the supply unit 5 and the modem 7 are depicted inside the cabinet 10, for ease of illustration.

[0044] Each of the accelerometric sensors 2, that is positioned at a point of the structure 20 (and is integral thereto) continuously measures the three acceleration components related to the three intrinsic orthogonal axes of the above-mentioned accelerometric sensor 2 (as is best described below). The measurements, continuously carried out by the accelerometric sensors 2, are transmitted in real time to the data logger 3 that processes and possibly records such measurements, operating in accordance with preset operating procedures, according to what is described below.

[0045] The monitoring system 1 for monitoring a structure, in particular said structure being the structure 20 of a building, a bridge, or another structure; said monitoring system 1 is characterized in that it comprises one or more data loggers 3 and one or more, in particular a plurality of, accelerometric sensors 2 connected to said one or more data loggers 3; one or more, in particular each, of said one or more accelerometric sensors 2 is a variable configuration accelerometric sensor.

[0046] In more detail, advantageously, the monitoring system 1 , according to the present first preferred embodiment of the present invention, comprises a data logger 3 and a plurality of accelerometric sensors 2, in particular according to this first preferred embodiment, twenty accelerometric sensors 2, connected to the data logger 3; each of said accelerometric sensors 2 is a variable configuration accelerometric sensor.

[0047] The monitoring system 1 is such that one or more, in particular each, of the one or more accelerometric sensors 2 comprised in said monitoring system 1 is a variable configuration accelerometric sensor such that said accelerometric sensor 2, during the operational life of said monitoring system 1 , is able to work at least in a first working condition and in a second working condition.

[0048] In more detail, advantageously the monitoring system 1 is such that each of the twenty accelerometric sensors 2 is a variable configuration accelerometric sensor such that said accelerometric sensor 2, during the operational life of the monitoring system 1 , is able to work at least in a first working condition and in a second working condition.

[0049] The monitoring system 1 is continuously operating.

[0050] The monitoring system 1 is such that one or more, in particular each, of the one or more accelerometric sensors 2 comprised in the same monitoring system 1 is a variable configuration accelerometric sensor such that said accelerometric sensor 2, during the operational life of said monitoring system 1 , is able to operate, in addition to the first and second working conditions, also in one or more other working conditions, in particular in a third working condition.

[0051] In more detail, advantageously, the monitoring system 1 is such that each of the (twenty) accelerometric sensors 2 is a variable configuration accelerometric sensor such that said accelerometric sensor 2, during the operational life of said monitoring system 1 , is able to operate, in addition to the first and second working conditions, also in a third working condition.

[0052] The monitoring system 1 is such that at least one, in particular each, of the accelerometric sensors 2 comprised in said monitoring system 1 measures the acceleration component according to an intrinsic axis of said accelerometric sensor 2, or measures the two acceleration components according to two intrinsic orthogonal axes of said accelerometric sensor 2, or measures the three acceleration components related to the three intrinsic orthogonal axes of said accelerometric sensor 2, and transmits such measures to the data logger 3 to which said accelerometric sensor 2 is connected.

[0053] In more detail, advantageously, the monitoring system 1 is such that each of the (twenty) accelerometric sensors 2 measures the three acceleration components related to the three intrinsic orthogonal axes of the same accelerometric sensor 2, and transmits such measures to the data logger 3, to which said accelerometric sensor 2 is connected.

[0054] The three intrinsic orthogonal axes of an accelerometric sensor 2 are the three orthogonal axes (inside the same accelerometric sensor 2) with respect to which the accelerometer comprised in the above-mentioned accelerometric sensor 2 measures the accelerations.

[0055] Herein below, for ease of explanation, it is considered that each accelerometric sensor 2 is positioned at the structure 20 so that the third intrinsic axis (axis z) of the same accelerometric sensor 2 is vertical (is in the direction of the gravitational acceleration).

[0056] The monitoring system 1 is such that, one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 processes and / or manages the measurements carried out by each of the one or more accelerometric sensors 2 connected to said data logger 3 and is able to operate with at least one accelerometric sensor 2 that is in the first working condition and / or with at least one accelerometric sensor 2 that is in the second working condition and / or with at least one accelerometric sensor 2 that is in the third working condition.

[0057] In more detail, advantageously, the monitoring system 1 is such that the data logger 3 processes and / or manages the measurements carried out by each of the (twenty) accelerometric sensors 2 connected to said data logger 3 and is able to operate with one or more accelerometric sensors 2 that are in the first working condition and / or with one or more accelerometric sensors 2 that are in the second working condition and / or with one or more accelerometric sensors 2 that are in the third working condition, as is best described herein below.

[0058] The monitoring system 1 is such that the configuration, in particular the working condition, of one or more, in particular of each, of the one or more accelerometric sensors 2, during the operational life of said monitoring system 1 , is changed, in particular is changed one or more times every twenty-four hours, by the data logger 3 to which the same accelerometric sensor 2 is connected.

[0059] In more detail, advantageously, the monitoring system 1 is such that the configuration, in particular the working condition, of one or more, in particular of each, of the one or more accelerometric sensors 2, during the operational life of the monitoring system 1 , is changed, in particular is changed one or more times every twenty-four hours, by the data logger 3 to which the same accelerometric sensor 2 is connected.

[0060] As is described in more detail herein below, following the commands given by the 3 operating in accordance with a given operating procedure (such as the first operating procedure, the second operating procedure and the fourth operating procedure described below), one or more, in particular each, of the accelerometric sensors 2 vary their working condition; in particular, at least some of the accelerometric sensors 2, multiple times during the 24-hour time frame of every day in the operational life of the monitoring system 1 , vary their working condition, following the commands given by the data logger 3 operating in accordance with the above-mentioned operating procedure. The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2 comprised in said monitoring system 1 is provided with a first threshold value relating to one or two or three of the three acceleration components according to one axis or two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor 2, or is provided with a first threshold value relating to the modulus of the acceleration vector, or is provided with two first threshold values relating to two or three of the three acceleration components according to two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor 2, or is provided with three first threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0061] In more detail, advantageously, the monitoring system 1 is such that each of the (twenty) accelerometric sensors 2 (comprised in the monitoring system 1 ) is provided with three first threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0062] The first threshold values, according to the present first preferred embodiment, are equal for all the accelerometric sensors 2; it is understood that, according to other embodiments, the first threshold values of each accelerometric sensor 2 can be different from the first threshold values of one or more of the other accelerometric sensors 2.

[0063] The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2 comprised in said monitoring system 1 is provided with a second threshold value relating to one or two or three of the three acceleration components according to one axis or two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor 2, or is provided with a second threshold value relating to the modulus of the acceleration vector, or is provided with two second threshold values relating to two or three of the three acceleration components according to two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor 2, or is provided with three second threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0064] In more detail, advantageously, the monitoring system 1 is such that each of the (twenty) accelerometric sensors 2 (comprised in the monitoring system 1 ) is provided with three second threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0065] The second threshold values, according to the present first preferred embodiment, are equal for all the accelerometric sensors 2; it is understood that, according to other embodiments, the second threshold values of each accelerometric sensor 2 can be different from the second threshold values of one or more of the other accelerometric sensors 2.

[0066] The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2 comprised in said monitoring system 1 is provided with one main threshold value relating to one or two or three of the three acceleration components according to one axis or two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor 2, or is provided with one main threshold value relating to the modulus of the acceleration vector, or is provided with two main threshold values relating to two or three of the three acceleration components according to two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor 2, or is provided with three main threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0067] In more detail, advantageously, the monitoring system 1 is such that each of the (twenty) accelerometric sensors 2 (comprised in the monitoring system 1 ) is provided with three main threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0068] The main threshold values, according to the present first preferred embodiment, are equal for all the accelerometric sensors 2; it is understood that, according to other embodiments, the main threshold values of each accelerometric sensor 2 can be different from the main threshold values of one or more of the other accelerometric sensors 2.

[0069] According to an implementation variation of the present first preferred embodiment, each accelerometric sensor 2 is provided with only one first threshold value that is equal for the three intrinsic orthogonal axes of the above-mentioned accelerometric sensor 2, is provided with only one second threshold value that is equal for the three intrinsic orthogonal axes of the above-mentioned accelerometric sensor 2 and is provided with only one main threshold value that is equal for the three intrinsic orthogonal axes of the above-mentioned accelerometric sensor 2.

[0070] According to another implementation variation of the present first preferred embodiment, in order to check whether an accelerometric sensor, at a given moment, is over-threshold (according to what is best specified herein below in the present description), reference is made to the modulus of the acceleration vector and not to each of the three components of the acceleration vector; in this case, the above-mentioned accelerometric sensor is provided with a first threshold value relating to the modulus of the acceleration vector, with a second threshold value relating to the modulus of the acceleration vector, and with a main threshold value relating to the modulus of the acceleration vector.

[0071] In the present description and in the attached claims, an accelerometric sensor, at a given moment is identified as an accelerometric sensor over-threshold if, following the measurements carried out by the same accelerometric sensor, at least one of the components of the same acceleration, or the modulus of the acceleration vector, is respectively higher than the threshold value relating to such acceleration component or than the threshold value relating to the modulus of the acceleration vector; the above- mentioned threshold values are the threshold values relating to the above- mentioned accelerometric sensor.

[0072] By the term “threshold values” reference is made, according to the context where the term appears, either to the first threshold values, o to the second threshold values, or to the main threshold values.

[0073] The monitoring system 1 is such that one or more, in particular each, of the one or more accelerometric sensors 2 comprised in said monitoring system 1 is triaxial.

[0074] In more detail, advantageously, the monitoring system 1 is such that each of the twenty accelerometric sensors 2 is triaxial.

[0075] The monitoring system 1 is such that one or more, in particular each, of the one or more accelerometric sensors 2 comprised in said monitoring system 1 is provided with one or with two or with three first threshold values, in particular with three first threshold values, relating to the three intrinsic orthogonal axes of the same accelerometric sensor 2, is provided with one or with two or with three second threshold values, in particular with three second threshold values, relating to the three intrinsic orthogonal axes of said accelerometric sensor 2, and is provided with one or with two or with three main threshold values, in particular with three main threshold values, relating to the three intrinsic orthogonal axes of said accelerometric sensor 2.

[0076] In more detail, advantageously, the monitoring system 1 is such that each of the accelerometric sensors 2 is provided with three first threshold values, with three second threshold values and with three main threshold values.

[0077] The monitoring system 1 is such that in one or more, in particular in each, of the one or more accelerometric sensors 2 comprised in said monitoring system 1 , the one or more second threshold values are not greater than, respectively, the one or more first threshold values, in particular are not greater than 70% of said one or more first threshold values; furthermore, the one or more main threshold values are greater than, respectively, said one or more first threshold values.

[0078] In more detail, advantageously, the monitoring system 1 is such that, in each of the (twenty) accelerometric sensors 2, the second threshold values are not greater than 70% of the first threshold values, in particular are equal to 50% of the first threshold values. Furthermore, the main threshold values are greater than the first threshold values, in particular, for example, are equal to 140% of the first threshold values.

[0079] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 is able to operate according to the “threshold-based” criterion and according to the “time-based” criterion.

[0080] In more detail, advantageously, the monitoring system 1 is such that, the data logger 3 is able to work according to the “threshold-based” criterion and according to the “time-based” criterion, as is described in detail herein below in the present description.

[0081] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 is able to work according to the “threshold-based” criterion so that the same data logger 3 identifies, during the operational life of said monitoring system 1 , when one or more of the one or more accelerometric sensors 2 connected to said data logger 3 are over-threshold relative to one or more of the one or more first threshold values or relative to one or more of the one or more second threshold values or relative to one or more of the one or more main threshold values, relating to said one or more accelerometric sensors 2. In more detail, advantageously, the monitoring system 1 is such that, the data logger 3 is able to work according to the “threshold-based” criterion so that the same data logger 3 identifies, during the operational life of the monitoring system 1 , when one or more of the accelerometric sensors 2, connected to the data logger 3, are over-threshold relative to one or more of the above-mentioned three first threshold values or relative to one or more of the above-mentioned three second threshold values or relative to one or more of the above-mentioned three main threshold values, relating to said one or more accelerometric sensors 2.

[0082] Described herein below are three operating modes of the data logger 3 comprised in the monitoring system 1 , in particular, a first operating mode, a second operating mode and a third operating mode of the data logger 3 are described.

[0083] The monitoring system 1 is such that, in accordance with a first operating mode, one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , with respect to the one or more accelerometric sensors 2 connected to the same data logger 3, works with the “threshold-based” criterion such that said data logger 3 stores in its mass storage, in particular in a first sector of said mass storage, the measurements carried out by said one or more accelerometric sensors 2 during each event whereby, following said event, the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, a preset first design number.

[0084] In more detail, advantageously, the monitoring system 1 is such that, in accordance with the first operating mode, the data logger 3, with respect to the (twenty) accelerometric sensors 2 connected to the same data logger 3, works with the “threshold-based” criterion such that the data logger 3 stores in its mass storage, in particular in a first sector of said mass storage, the measurements carried out by said (twenty) accelerometric sensors 2 during each event whereby, following said event, the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, the preset first design number.

[0085] In the present description and in the attached claims, a “significant event” is an event during which the number of the accelerometric sensors that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, the preset first design number.

[0086] In the present description and in the attached claims by the term "... the number of the accelerometric sensors ... that are over-threshold ...” or by similar terms, "... the number of the accelerometric sensors ... that are overthreshold ...” in a certain time interval having a preset duration is meant, which time interval is taken as a reference to determine whether the above- mentioned accelerometric sensors are (conventionally) to be intended come “concurrently” over-threshold.

[0087] Therefore, each time reference is made to multiple accelerometric sensors that are over-threshold, while not being explicitly expressed not to burden the description, reference is made to the above-mentioned time interval having a preset duration in which the above-mentioned one or more accelerometric sensors are all over-threshold. Similar considerations apply also with respect to the term “below-threshold”.

[0088] The monitoring system 1 is such that the above-mentioned preset first design number is equal to one.

[0089] The monitoring system 1 is such that it comprises one or more data loggers 3 and a plurality of accelerometric sensors 2; additionally, in accordance with a second operating mode, one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , with respect to one or more accelerometric sensors 2 connected to the same data logger 3, works with the “threshold-based” criterion such that said data logger 3 stores in its mass storage, in particular in the first sector of said mass storage, the measurements carried out by said one or more accelerometric sensors 2 during each event whereby, following said event, the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, the preset first design number; additionally, in accordance with said second operating mode, said data logger 3, concurrently, with respect to one or more other accelerometric sensors 2, connected to said data logger 3, works with the “time-based” criterion such that said data logger 3 stores in its mass storage, in particular in a second sector of said mass storage, the measurements carried out by said one or more other accelerometric sensors 2, independently of the values of the accelerations as measured by said one or more other accelerometric sensors 2.

[0090] In more detail, advantageously, in accordance with the second operating mode, the data logger 3, with respect to ten accelerometric sensors 2 (connected to the data logger 3) (indicated in the Figures 4 and 5 with “2a”) works with the “threshold-based” criterion such that the data logger 3 stores in its mass storage, in particular in the first sector of said mass storage, the measurements carried out by the above-mentioned ten accelerometric sensors 2 during each event whereby, following said event, the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding three first threshold values is equal to, or greater than, the above-mentioned first design number. Moreover, in accordance with the second operating mode, the data logger 3, concurrently, with respect to the other ten accelerometric sensors 2 (connected to the data logger 3) (indicated in the Figures 4 and 5 with “2b”) works with the “time-based” criterion such that the data logger 3 stores in its mass storage, in particular in the second sector of said mass storage, the measurements carried out by said other ten accelerometric sensors 2, independently of the values of the accelerations as measured by said other accelerometric sensors 2.

[0091] The monitoring system 1 is such that, in accordance with a third operating mode, one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , with respect to the one or more accelerometric sensors 2 connected to the same data logger 3, works with the “time-based” criterion such that said data logger 3 stores in its mass storage, in particular in the second sector of said mass storage, the measurements carried out by the one or more accelerometric sensors 2 connected to said data logger 3, independently of the values of the accelerations as measured by said one or more accelerometric sensors 2.

[0092] In more detail, advantageously, the monitoring system 1 is such that, in accordance with the third operating mode, the data logger 3, with respect to the (twenty) accelerometric sensors 2 connected to the same data logger 3, works with the “time-based” criterion such that the data logger 3 stores in its mass storage, in particular in the second sector of said mass storage, the measurements carried out by the (twenty) accelerometric sensors 2, independently of the values of the accelerations as measured by the same accelerometric sensors 2.

[0093] In accordance with the first operating mode, the monitoring system 1 is such that the data logger 3, with respect to the twenty accelerometric sensors 2 connected thereto, works with the “threshold-based” criterion that provides, in the case of significant events, for the storage of the measurements carried out by the (twenty) accelerometric sensors 2 connected to the same data logger 3; the (twenty) accelerometric sensors 2 are in the first working condition.

[0094] In accordance with the second operating mode, the monitoring system 1 is such that the data logger 3, with respect to ten accelerometric sensors 2 (indicated in the Figures 4 and 5 with “2a”) works with the “threshold-based” criterion that provides, in the case of significant events, for the storage of the measurements carried out by the above-mentioned ten accelerometric sensors 2; concurrently, the data logger 3, with respect to the remaining ten accelerometric sensors 2 (indicated in the Figures 4 and 5 with “2b”), works with the “time-based” criterion that provides for the storage of the measurements carried out by the above-mentioned remaining ten accelerometric sensors 2, independently of the values of the accelerations as measured by the above-mentioned remaining ten accelerometric sensors 2. The above-mentioned (ten) accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion are in the first working condition; the above-mentioned (ten) accelerometric sensors 2 with respect to which the data logger 3 works with the “time-based” criterion are in the second working condition.

[0095] In accordance with the third operating mode, the monitoring system 1 is such that the data logger 3, with respect to the twenty accelerometric sensors 2 connected thereto, works with the “time-based” criterion that provides for the storage of the measurements carried out by the (twenty) accelerometric sensors 2 connected to the same data logger 3, independently of the values of the accelerations as measured by the above- mentioned (twenty) accelerometric sensors 2; the (twenty) accelerometric sensors 2 are in the second working condition.

[0096] The above-mentioned “threshold-based operation” is described in detail herein below.

[0097] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , when with respect to one or more accelerometric sensors 2 connected to said data logger 3 works with the “threshold-based” criterion, begins to store in its mass storage, in particular in the first sector of said mass storage, of the measurements carried out by said one or more accelerometric sensors 2, each time an event occurs, as a result of which the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, the preset first design number; said data logger 3, at the beginning of each storing, stores in said first sector of its mass storage the measurements carried out by said one or more accelerometric sensors 2 relating to a preset pre-trigger time interval (a time interval before activating the storing).

[0098] In more detail, advantageously, the monitoring system 1 is such that the data logger 3, when with respect to a given number of accelerometric sensors 2 (according to the present first preferred embodiment, such number is equal to ten with reference to the second operating mode and is equal to twenty with reference to the first operating mode) (connected to the data logger 3) works with the “threshold-based” criterion, begins to store in its mass storage, in particular in the first sector of said mass storage, of the measurements carried out by the above-mentioned accelerometric sensors 2 (with respect to which said data logger 3 works with the “threshold-based” criterion), each time an event occurs, as a result of which the number of the accelerometric sensors 2 (according to the present first preferred embodiment, all the (twenty) accelerometric sensors 2 comprised in the monitoring system 1 are checked; see below) that are over-threshold with respect to one or more of the (corresponding) three first threshold values is equal to, or greater than, the preset first design number.

[0099] As set forth above, according to the present first preferred embodiment, all the accelerometric sensors 2 have the same first threshold values, the same second threshold values, and the same main threshold values.

[0100] The data logger 3, at the beginning of each storing, stores in the first sector of its mass storage the measurements carried out by said accelerometric sensors 2 (with respect to which said data logger 3 works with the “threshold-based” criterion) relating to a preset pre-trigger time interval.

[0101] During the operational life of the monitoring system 1 , referring to at any given moment “t” when the accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion carry out the measurements of the accelerations, it turns out that in the data logger 3 the measurements are temporarily stored carried out by the above- mentioned accelerometric sensors 2 during a “movable” time interval (which is updated at each moment when the measurements of the accelerations are carried out); the above-mentioned “movable” time interval has always the same preset duration, which is the duration of the pre-trigger time interval, and is such that the final instant of the above-mentioned time interval coincides with the above-mentioned any given moment “t”.

[0102] In the case a significant event occurs, the data logger (such as the data logger 3) stores in the first sector of its mass storage the measurements carried out by all the accelerometric sensors with respect to which the same data logger is working according to the “threshold-based” criterion.

[0103] With reference to the monitoring system 1 , a significant event is an event during which the number of the accelerometric sensors 2 that are overthreshold with respect to one or more of the corresponding three first threshold values is equal to, or greater than, the above-mentioned first design number. A significant event can be a seismic event affecting the structure 20.

[0104] The determination of the above-mentioned first design number, as well as the determination, for each accelerometric sensor 2, of the one or more first threshold values, of the one or more second threshold values and of the one or more main threshold values, in particular of the three first threshold values, of the three second threshold values and of the three main threshold values, falls withing the activities relating to the design of the monitoring (using the monitoring systeml ) related to the structure 20. Such monitoring design activities relating to the structure 20, among alia, aim to store the data of events that can be of interest, trying to avoid storing data relating to completely insignificant events. In fact, for example, a single accelerometric sensor 2 may go over-threshold due to an event of no significance, such as a small impact occurring in the proximity of the above-mentioned accelerometric sensor 2.

[0105] The monitoring system 1 is such that the above-mentioned preset first design number, as already set forth above, is equal to one.

[0106] Therefore, the data logger 3 begins to store the data provided by all the accelerometric sensors 2 with respect to which the same data logger 3 works with the “threshold-based” criterion as soon as one of the twenty accelerometric sensors 2 is over-threshold, with respect to one or more of the (corresponding) three first threshold values.

[0107] The monitoring system 1 is such that said data logger 3, once the storage of said event has begun, the storage of the measurements carried out by said one or more accelerometric sensors 2, with respect to which said data logger 3 works with the “threshold-based” criterion, continues for as long as the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more second threshold values is equal to, or greater than, a preset second design number.

[0108] In more detail, advantageously, the monitoring system 1 is such that the data logger 3, once the storage of the above-mentioned event has begun, the storage of the measurements carried out by accelerometric sensors 2, with respect to which said data logger 3 works with the “threshold-based” criterion, continues for as long as the number of the accelerometric sensors 2 (according to the present first preferred embodiment, all the (twenty) accelerometric sensors 2 comprised in the monitoring system 1 are checked; see below) that are over-threshold with respect to one or more of the corresponding three second threshold values is equal to, or greater than, the above-mentioned second design number.

[0109] According to the present first preferred embodiment, the above- mentioned preset second design number is equal to one.

[0110] The data logger 3 continues the storage of the measurements carried out by the accelerometric sensors 2, with respect to which said data logger 3 works with the “threshold-based” criterion, for as long as at least one accelerometric sensor 2 is over-threshold with respect to one or more of the above-mentioned (three) second threshold values.

[0111] The monitoring system 1 is such that said data logger 3 starts the end- of-storage step in its mass storage, in particular in said first sector of said mass storage, of the measurements carried out by said one or more accelerometric sensors 2 with respect to which said data logger 3 works with the “threshold-based” criterion, when the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more second threshold values is less than the preset second design number.

[0112] In more detail, advantageously, the monitoring system 1 is such that the data logger 3 starts the end-of-storage step in its mass storage, in particular in the above-mentioned first sector of said mass storage, of the measurements carried out by said accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion, when the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding three second threshold values is less than the preset second design number; in particular, the data logger 3 starts the end-of-storage step in the above-mentioned first sector of said mass storage, of the measurements carried out by said accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion, when no accelerometric sensor 2 is over-threshold with respect to one or more of the (corresponding) three second threshold values.

[0113] As set forth above, the above-mentioned second design number is equal to one, so that the data logger 3 begins the above-mentioned end-of- storage step when no accelerometric sensor 2 is over-threshold, with respect to one or more of the (three) second threshold values.

[0114] The first design number, the second design number and the third design number, which will be introduced below, are integral (natural) numbers. Therefore, a number of accelerometric sensors 2 less than one (the above-mentioned second design number is equal to one) equals to “no accelerometric sensor”.

[0115] The monitoring system 1 is such that said data logger 3, in order to implement said end-of-storage step, during a preset post-trigger time interval (time interval after the storing of the event) that starts from the moment when said end-of-storage step starts, stores the measurements carried out by said one or more accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion. Said data logger 3, during said post-trigger time interval, controls that the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more second threshold values is constantly less than said preset second design number; if, during said post-trigger time interval, the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more second threshold values, at any given moment comprised in said post-trigger time interval, is equal to, or greater than, said preset second design number, from said moment, the post-trigger time interval starts again. Said data logger 3 ends the storage of the measurements relating to said event when the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more second threshold values, for an entire post-trigger time interval, remains less than said preset second design number.

[0116] In more detail, advantageously, the monitoring system 1 is such that the data logger 3, in order to implement the end-of-storage step, during a preset post-trigger time interval that starts from the moment when said end- of-storage step starts, stores the measurements carried out by said accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion. The data logger 3, during said post-trigger time interval, controls that the number of the accelerometric sensors 2 (according to the present first preferred embodiment, all the (twenty) accelerometric sensors 2 comprised in the monitoring system 1 are checked; see below) that are over-threshold with respect to one or more of the (corresponding) three second threshold values, is constantly less than the second design number that, according to the present first preferred embodiment, is equal to one; if, during said post-trigger time interval, the number of the accelerometric sensors 2 (according to the present first preferred embodiment all the (twenty) accelerometric sensors 2 comprised in the monitoring system 1 are controlled; see below) that are over-threshold with respect to one or more of the (corresponding) three second threshold values, at any given moment comprised in the post-trigger time interval, is equal to, or greater than, the above-mentioned second design number, from said moment, the post-trigger time interval starts again.

[0117] The data logger 3 ends the storage of the measurements relating to said event when the number of the accelerometric sensors 2 that are overthreshold with respect to one or more of the (corresponding) three second threshold values, for an entire post-trigger time interval, remains less than the second design number; in particular, the data logger 3 ends the storage of the measurements relating to said event when for an entire post-trigger time interval, no accelerometric sensor 2 is over-threshold with respect to one or more of the (corresponding) three second threshold values.

[0118] Considered that the above-mentioned preset second design number is equal to one, the data logger 3, ends the storage of the measurements relating to said event when all the one or more accelerometric sensors 2, for an entire post-trigger time interval, remain below-threshold, with respect to each of the three second threshold values relating to the accelerometric sensors 2.

[0119] According to a further implementation variation, during the end-of- storage step, the data logger 3 can make reference, instead of to the one or more second threshold values, to the one or more first threshold values and, instead of to the second design number, to the first design number.

[0120] The monitoring system 1 is such that said first design number and said second design number are determined by taking into account all the accelerometric sensors 2 connected to one of the one or more data loggers 3 comprised in said monitoring system 1.

[0121] In more detail, advantageously, the monitoring system 1 is such that the first design number and the second design number are determined by taking into account all the (twenty) accelerometric sensors 2 connected to the data logger 3.

[0122] The data logger 3, in accordance with the first operating mode and with the second operating mode, begins to store in the above-mentioned first sector of its mass storage the measurements carried out by the accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion each time that one of the (twenty) accelerometric sensors 2 (connected to the data logger 3) is above the threshold with respect to at least one of the three first threshold values.

[0123] In addition, the data logger 3 ends the storage of the measurements relating to said event when all the (twenty) accelerometric sensors 2, for an entire post-trigger time interval, remain below-threshold, with respect to each of the three second threshold values.

[0124] According to a further implementation variation of the present first preferred embodiment, the following is given.

[0125] The monitoring system 1 is such that, according to the present implementation variation, said first design number and said second design number are determined by taking into account only the accelerometric sensors 2 with respect to which one of the one or more data loggers 3 comprised in said monitoring system 1 works with the “threshold-based” criterion.

[0126] In more detail, advantageously, the monitoring system 1 is such that, according to the present implementation variation, the first design number and the second design number are determined by taking into account only the accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion.

[0127] What has been described above with reference to the case when each accelerometric sensor (such as each of the accelerometric sensors 2) is provided with three first threshold values, with three second threshold values and with three main threshold values relating to the three intrinsic axes of the same accelerometric sensor 2, is valid, with the appropriate changes, even in the case that each accelerometric sensor is provided with a first threshold value, with a second threshold value and with a main threshold value, each of which is equal for all the three intrinsic axes of the above-mentioned accelerometric sensor.

[0128] Furthermore, generally, what has been described above with reference to the case when each accelerometric sensor (such as each of the accelerometric sensors 2) is provided with three first threshold values, with three second threshold values and with three main threshold values relating to the three intrinsic axes of the same accelerometric sensor 2 is valid, with the appropriate changes, even in the case that each accelerometric sensor is provided with two first threshold values, one of which relates to the vertical direction and the other one relates to each of the two orthogonal horizontal directions (the latter threshold value is the same for the above-mentioned two horizontal directions), with two second threshold values, one of which relates to the vertical direction and the other one relates to each of the two orthogonal horizontal directions (the latter threshold value is the same for the above- mentioned two horizontal directions), and with two main threshold values, one of which relates to the vertical direction and the other one relates to each of the two orthogonal horizontal directions (the latter threshold value is the same for the above-mentioned two horizontal directions).

[0129] Furthermore, generally, what has been described above with reference to the case when each accelerometric sensor (such as each of the accelerometric sensors 2) is provided with three first threshold values, with three second threshold values and with three main threshold values relating to the three intrinsic axes of the same accelerometric sensor is valid, with the appropriate changes, even in the case that each accelerometric sensor is provided with a first threshold value, with a second threshold value and with a main threshold value, each of which is relating to the modulus of the acceleration vector.

[0130] The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2 is able to work in certain working conditions such that the same accelerometric sensor 2 is able to carry out acceleration measurements according to determined sampling frequencies to which one or more specific filters for processing the signals are associated.

[0131] In more detail, advantageously, the monitoring system 1 is such that, each of the (twenty) accelerometric sensors 2 is able to work in certain working conditions such that the same accelerometric sensor 2 is able to carry out acceleration measurements according to determined sampling frequencies to which one or more specific filters for processing the signals are associated.

[0132] The monitoring system 1 is such that one or more, in particular each, of the one or more accelerometric sensors 2 is able to carry out temperature measurements.

[0133] In more detail, advantageously, the monitoring system 1 is such that each of the twenty accelerometric sensors 2 is able to carry out temperature measurements.

[0134] The monitoring system 1 is such that each of the one or more accelerometric sensors 2 (according to the present first preferred embodiment, ten accelerometric sensors 2), when is in the first working condition, carries out the acceleration measurements according to a first sampling frequency by using one or more corresponding first filters for processing the signals.

[0135] Said first sampling frequency is greater than 300 Hz, in particular 500 Hz, preferably is about 1000 Hz.

[0136] According to the present first preferred embodiment, the first sampling frequency is equal to 1000 Hz.

[0137] The monitoring system 1 is such that each of the one or more accelerometric sensors 2 (according to the present first preferred embodiment, ten accelerometric sensors 2), when is in the second working condition, carries out the acceleration measurements in accordance with a second sampling frequency by using one or more corresponding second filters for processing the signals.

[0138] Said second sampling frequency is less than 200 Hz, in particular 150 Hz, preferably said second sampling frequency has a value of about 100 Hz.

[0139] According to the present first preferred embodiment the second sampling frequency is, for example, of about 100 Hz. To such low sampling frequency (for example, of about 100 Hz), a limited value of the noise is associated; in such a manner, the accelerometric sensors 2, in the second working condition, are able to detect also accelerations due to the environmental actions. Such features make the accelerometric sensors 2, when they are in the second working condition, able to carry out measurements that can be used for OMA analyses regarding the structure 20 (that is, the monitored structure).

[0140] The monitoring system 1 is such that each of the one or more accelerometric sensors 2, when in the third working condition, carries out the acceleration measurements according to a third sampling frequency by using one or more corresponding third filters for processing the signals.

[0141] Said third sampling frequency ranges between 150 Hz and 300 Hz. According to the present first preferred embodiment, the third frequency ranges between 200 Hz and 250 Hz.

[0142] The three operating modes described above, in generale, can be practiced according to various operating procedures. Hereinbelow, with reference to the monitoring system 1 according to the present first preferred embodiment and according to possible implementation variations illustrated below, a first, a second, a third, and a fourth operating procedure are described, and an “on command” operating procedure is described. The “on command” operating procedure, as is best described herein below, is possibly used during short period of the operational life of the monitoring system 1 , in specific circumstances where the first or the second or the third or the fourth operating procedure are inefficient or not optimized.

[0143] Generally, each of the above-mentioned four operating procedures can be active during one or more periods of the operational life of the monitoring system 1 ; such operating procedures, in fact, can be alternated, also multiple times, during the operational life of the monitoring system 1. Such four operating procedures, and also the “on command” operating procedure, are activated and disactivated remotely by communicating with the data logger 3. In alternative only one between the first operating procedure, the second operating procedure, the third operating procedure and the fourth operating procedure can be active during the whole operational life of the monitoring system 1. It is understood that, any period of the operational life of the monitoring system 1 being set, during said period only one of the above-mentioned four operating procedures is active.

[0144] Among the above-mentioned four operating procedures, preferred is considered the first operating procedure, which is described herein below before the other operating procedures.

[0145] The monitoring system 1 comprises one or more data loggers 3 and a plurality of accelerometric sensors 2; additionally, during one or more periods of the operational life, in particular during the whole operational life, of said monitoring system 1 , one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , in accordance with a first operating procedure, operates in accordance with the second operating mode both within preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and when an event occurs such that the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding one or more main threshold values is equal to, or greater than, a preset third design number; furthermore, the same data logger 3 operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system 1 .

[0146] In more detail, advantageously, the monitoring system 1 comprises a data logger 3 and twenty accelerometric sensors 2; furthermore, during one or more periods of the operational life, in particular during the whole operational life, of the monitoring system 1 , the data logger 3, in accordance with the first operating procedure, operates in accordance with the second operating mode both within preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency (see below), and when an event occurs such that the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding (three) main threshold values is equal to, or greater than, the preset third design number; the same data logger 3 operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of the monitoring system 1 .

[0147] In the present description and in the attached claims, a “relevant event” is an event during which the number of the accelerometric sensors that are over-threshold with respect to one or more of the corresponding one or more main threshold values is equal to, or greater than, the preset third design number.

[0148] In accordance with the first operating procedure, when the data logger 3 operates according to the first operating mode, the (twenty) accelerometric sensors 2 are in the first working condition; when the data logger 3 operates in accordance with the second operating mode, the (ten) accelerometric sensors 2 with respect to which the same data logger 3 work with the “threshold-based” criterion (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2a”) are in the first working condition and the remaining (ten) accelerometric sensors 2 with respect to which the data logger 3 works with the “time-based” criterion (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2b”) are in the second working condition. The latter accelerometric sensors 2 (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2b”) are, thus, in the second working condition both within preset time intervals suitably spaced apart, and “immediately after” a “relevant event” affecting the structure 20, monitored by the monitoring system 1. Each of such accelerometric sensors 2, at the beginning of each of the above-mentioned preset time intervals passes from the first working condition to the second working condition and, at the end of each of the above-mentioned preset time intervals, passes from the second working condition alia primate the first working condition.

[0149] In accordance with the first operating procedure, ten accelerometric sensors 2 (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2a”) are always in the first working condition and ten accelerometric sensors 2 (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2b”) are alternately either in the first working condition or in the second working condition.

[0150] The monitoring system 1 is such that said preset third design number is equal to one.

[0151] In the case of the monitoring system 1 , a relevant event is an event during which (the above-mentioned third design number is equal to one) one or more of the accelerometric sensors 2 is over-threshold relative to at least one of the (three) main threshold values.

[0152] In the monitoring system 1 , the data logger 3, in accordance with the first operating procedure (described above ), every day, in the 24-hour period, in the absence of relevant events for the structure 20 (which is the monitored structure) operates in accordance with the second operating mode, for example, during a time equal to 120 minutes divided into four time intervals, each of 30 minutes, equally spaced apart; during the remaining time, equal to 22 hours, the data logger 3 operates in accordance with the first operating mode (described above ).

[0153] The duration of each of the above-mentioned time intervals, considered here as equal to 30 minutes, according to the situations, can be, for example, equal to 15, or even 60 minutes. Furthermore, during the 24 hours, the number of the intervals during which the monitoring system 1 operates in accordance with the second operating mode can be, for example, equal to six, rather than four, or, in certain cases, it can be less than four. In the case that, when the data logger 3 operates in accordance with the first operating mode, a relevant event occurs, it is found that, one such relevant event has ended, the data logger 3 begins, “immediately after” (for example, after a few tens of seconds), to operate in accordance with the second operating mode; furthermore, the monitoring system 1 continues to operate in accordance with the second operating mode for a suitable time interval that is repeated a preset number of times, according to a preset time frequency in accordance with what is provided for in the first operating procedure.

[0154] The data measured in accordance with the second operating mode after the relevant event, once they have been transmitted by the data logger 3 to the server 9, are available to be analysed and processed by specific algorithms able to identify some significant parameters about the dynamic characterization of the structure 20. From a comparison between the results obtained before (by the above-mentioned specific algorithms), regarding time intervals that precede the above-mentioned relevant event, and the data relating to the time intervals “immediately after” the relevant event, it is possible to obtain information concerning the possible damage suffered by the structure 20 following the above-mentioned relevant event.

[0155] Such first operating procedure ensures, among alia, that, even in the absence of an Internet connection between the monitoring system 1 and any operator working remotely, the second operating mode is automatically activated “immediately after” the relevant event. Even in the case that the Internet connection is temporarily interrupted, for example following the above-mentioned relevant event (such as a seismic event), the measurements carried out in accordance with the second operating mode “immediately after” the relevant event remain in the mass storage of the data logger 3 and are transmitted to the server 9 when the Internet connection is restored. It is important to be able to perform, after the seismic event, analyses coming from the processing operations of the measurements carried out by the monitoring system 1 , which analyses allow obtaining information on the post-event situation of the structure 20.

[0156] In the monitoring system 1 , at least during a given period, in particular during the whole operational life of the monitoring system 1 , the data logger 3 can operate in accordance with a second operating procedure, as is best illustrated herein below.

[0157] The monitoring system 1 comprises one or more data loggers 3 and a plurality of accelerometric sensors 2; additionally, during one or more periods of the operational life, in particular during the whole operational life, of said monitoring system 1 , one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , in accordance with a second operating procedure, operates in accordance with the second operating mode in preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system 1 .

[0158] In more detail, advantageously, the monitoring system 1 comprises one or more data loggers 3 and a plurality of accelerometric sensors 2; additionally, during one or more periods of the operational life, in particular during the whole operational life, of the monitoring system 1 , the data logger 3, in accordance with the second operating procedure, operates in accordance with the second operating mode in preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency (see below), and operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system 1.

[0159] In accordance with the second operating procedure, when the data logger 3 operates according to the first operating mode, the (twenty) accelerometric sensors 2 are in the first working condition; when the data logger 3 operates in accordance with the second operating mode, the (ten) accelerometric sensors 2 with respect to which the same data logger 3 work with the “threshold-based” criterion (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2a”) are in the first working condition and the remaining (ten) accelerometric sensors 2 with respect to which the data logger 3 works with the “time-based” criterion (such accelerometric sensors 2 are indicated in the Figures 4 and 5 with “2b”) are in the second working condition.

[0160] Such second operating procedure differs from the first operating procedure in that, in accordance with the second operating procedure, the data logger 3 operates in accordance with the second operating mode only in preset time intervals, without taking into account the one or more, in particular the three, main threshold values, hence without activating the second operating mode “immediately after” a relevant event.

[0161] In absence of relevant events, the data logger 3, in accordance with the first operating procedure, behaves in the same manner as the same data logger 3 does in accordance with the above-mentioned second operating procedure.

[0162] In accordance with the second operating procedure, after a relevant event (but not “immediately after”), data are obtained, from which it is possible, by the specific algorithms mentioned above, to carry out analyses that allow getting information on the situation of the structure 20.

[0163] In the case that the second operating procedure provides for actuating the second operating mode (with respect to the accelerometric sensors 2 that are in the second working condition) with a considerable frequency, for example six times a day, it is found that such second operating mode is in any case actuated “soon after” the seismic event, even if not “immediately after” the seismic event, whichever the time interval when the seismic event occurs is; however, in the case that the second operating procedure provides for actuating the second operating mode with a lower frequency, it can be very advantageous to actuate the second operating mode “immediately after” the seismic event; in this case, the advantages related to the use of the first operating procedure instead of the second operating procedure are thereby highlighted.

[0164] The possibility to have data immediately after a relevant event also has the advantages that, in the case that, in a time interval of a limited duration, one or more other relevant events follow such relevant event, it becomes possible, by using the first operating procedure, to have information on the situation of the monitored structure (such as the structure 20) “immediately after” each of the above-mentioned relevant events.

[0165] In the monitoring system 1 , at least during a determined period, in particular during the whole operational life of the monitoring system 1 , the data logger 3 can operate in accordance with a third operating procedure, described below.

[0166] The monitoring system 1 is such that, during one or more periods of the operational life, in particular during the whole operational life, of said monitoring system 1 , one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , in accordance with a third operating procedure, operates in accordance with the first operating mode.

[0167] In more detail, advantageously, the monitoring system 1 is such that, during one or more periods of the operational life, in particular during the whole operational life, of the monitoring system 1 , the data logger 3 in accordance with the third operating procedure operates in accordance with the first operating mode. Each of the (twenty) accelerometric sensors 2 (connected to the same data logger 3) is in the first working condition.

[0168] In the monitoring system 1 , at least during a determined period, in particular during the whole operational life of the monitoring system 1 , the data logger 3 can operate in accordance with a fourth operating procedure, described below.

[0169] The monitoring system 1 is such that, during one or more periods of the operational life, in particular during the whole operational life, of said monitoring system 1 , one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , in accordance with a fourth operating procedure, operates in accordance with the third operating mode in preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system 1.

[0170] In more detail, advantageously, the monitoring system 1 is such that, in accordance with the fourth operating procedure, during one or more periods of the operational life, in particular during the whole operational life, of said monitoring system 1 , the data logger 3, in accordance with the fourth operating procedure, operates in accordance with the third operating mode in preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system 1.

[0171] In accordance with the fourth operating procedure, when the data logger 3 operates in accordance with the first operating mode, all the (twenty) accelerometric sensors 2 are in the first working condition, and when the data logger 3 operates in accordance with the third operating mode, all the (twenty) accelerometric sensors 2 are in the third working condition.

[0172] Compared to the case where the monitoring system 1 operates in accordance with the second operating procedure, when the monitoring system 1 operates in accordance with the fourth operating procedure, during the above-mentioned preset time intervals in which the data logger 3 works with the “time-based” criterion, no accelerometric sensor 2 works with the “threshold-based” criterion.

[0173] If, for example, it is desired to increase the number and / or duration of the time intervals in which the monitoring system 1 works with the “timebased” criterion, and if it is suitable to operate, in such time intervals, with the entirety of the accelerometric sensors 2 connected to the data logger 3, than it could be suitable, during such time intervals, to use the accelerometric sensors 2 that are in the third working condition and not in the second working condition, so that, in the case that, during such time intervals a significant event occurs (for example, a seismic event such that the number of the accelerometric sensors 2 that are over-threshold with respect to one or more of the corresponding three first threshold values is equal to, or greater than, the preset first design number, equal to one), the sampling frequency of the accelerometric sensors 2 is that of the third working condition, hence is greater than the one relating to the second working condition so as to be able to describe, in a sufficiently accurate manner, a seismic event that possibly stresses the structure 20 (the monitored structure).

[0174] The choice about the adoption either of the second operating procedure or the fourth operating procedure, and the choice of the operative conditions of the accelerometric sensors 2 are part of the activities regarding the monitoring design (using the monitoring system 1 ) of the structure 20, which is the monitored structure.

[0175] In summary, the following can be stated. In the monitoring system 1 , the data logger 3, in accordance with the first operating procedure, works most of the time with the “threshold-based” criterion with respect to the (twenty) accelerometric sensors 2 that are in the first working condition; in addition, the data logger 3, both within preset time intervals, and when a relevant event occurs, works with the “threshold-based” criterion with respect to the ten accelerometric sensors 2 that are in the first working condition and works with the “time-based” criterion with respect to the other ten accelerometric sensors 2 that are in the second working condition.

[0176] In the monitoring system 1 , the data logger 3, in accordance with the second operating procedure, works most of the time with the “thresholdbased” criterion with respect to the (twenty) accelerometric sensors 2 that are in the first working condition; in addition, the data logger 3, in preset time intervals, works with the “threshold-based” criterion with respect to the ten accelerometric sensors 2 that are in the first working condition and works with the “time-based” criterion with respect to the other ten accelerometric sensors 2 that are in the second working condition.

[0177] In the monitoring system 1 , the data logger 3, in accordance with the third operating procedure, works with the “threshold-based” criterion with respect to all the (twenty) accelerometric sensors 2 that are in the first working condition.

[0178] In the monitoring system 1 , the data logger 3, in accordance with the fourth operating procedure, works most of the time with the “threshold-based” criterion with the (twenty) accelerometric sensors 2 that are in the first working condition, and, in preset time intervals it works with the “time-based” criterion with all the (twenty) accelerometric sensors 2 that are in the second working condition or, according to what is illustrated above, are in the third working condition.

[0179] The monitoring system 1 is such that, in accordance with an “on command” operating procedure, one or more, in particular each, of the one or more data loggers 3, on command, in particular on a remote command, operates, in one or more time intervals having a preset duration, in accordance with the second operating mode or the third operating mode.

[0180] In more detail, advantageously, the monitoring system 1 is such that, in accordance with an “on command” operating procedure, the data logger 3, on a remote command, operates, in one or more time intervals having a preset duration, in accordance with the second operating mode or the third operating mode.

[0181] The “on command” operating procedure allows intervening remotely on the monitoring system 1 to actuate, at any given moment of the operational life of the same monitoring system 1 , the second operating mode or the third operating mode and, therefore, to be subsequently able to perform OMA analyses .

[0182] The “on command” operating procedure can be particularly useful in those cases when, in preset moments, especially after a relevant event, data relating to the structure 20 (that is the monitored structure) need to be known. According to the “on command” operating procedure, it is also possible, for example, to increase the number of the accelerometric sensors 2, with respect to which the data logger 3 operates according to the “time-based” criterion, which are able to provide information useful for the determination of the value of those entities permitting a dynamic identification of the structure 20.

[0183] The monitoring system 1 is such that one or more of, in particular all, said operating procedures, during the operational life of the monitoring system 1 , can be changed by communicating remotely with one or more of the one or more data loggers 3 comprised in said monitoring system 1 .

[0184] In more detail, advantageously, the monitoring system 1 is such that the first operating procedure, the second operating procedure, the third operating procedure, the fourth operating procedure and the “on command” operating procedure, during the operational life of said monitoring system 1 , can be changed by communicating remotely with the data logger 3.

[0185] In the monitoring system 1 , the data logger 3 may operate, during a determined period or even during its entire operational life, in accordance with the first operating procedure or also in accordance with the second operating procedure or in accordance with the third operating procedure or in accordance with the fourth operating procedure. The above-mentioned operating procedures can be changed during of the operational life of the monitoring system 1 so that the data logger 3, may operate, for example, according to one of the above-mentioned operating procedures in one or more periods of the operational life of the monitoring system 1 , and can operate according to another one of the above-mentioned operating procedures in other periods of the operational life of the same monitoring system 1 .

[0186] The “on command” operating procedure, as illustrated above, is a procedure that is useful in specific situations, and is adapted in one or more time intervals having generally a short duration.

[0187] The monitoring system 1 is such that to one or more, in particular to each of the one or more accelerometric sensors 2, by the data logger 3 to which the same accelerometric sensor 2 is connected, in particular on a remote command, the corresponding working condition is assigned on command; in particular the first working condition or the second working condition or the third working condition.

[0188] When, with reference to at least some of the accelerometric sensors 2, the data logger 3 works with the “threshold-based” criterion, the measurements carried out by the above-mentioned accelerometric sensors 2 are processed, at least mainly, to get information on the response of the (monitored) structure 20 to a dynamic action, such as a seismic event or an impact, applied onto the same structure 20. In particular, in the case of seismic event, the knowledge of the accelerations at the monitored points of the structure 20, provides important information relating to the response of same the structure 20 to the seismic event. From the measurements of the accelerations of the monitored points, it is also possible to retrieve other information relating, for example, to the relative displacement, in the elastic phase, of the above-mentioned monitored points.

[0189] The measurements carried out by the accelerometric sensors 2 when, with reference to said one or more accelerometric sensors 2, the data logger 3 works with the “time-based” criterion, in particular the measurements carried out by the accelerometric sensors 2 when they are in the second working condition, are processed, at least mainly, to perform OMA analyses, so as to identify, in various time intervals, during the operational life of the monitoring system 1 , the values of the proper frequencies, the values of the dampening and the modal forms of the (monitored) structure 20.

[0190] By periodically performing OMA analyses by the monitoring system 1 and comparing the various “situations” of the (monitored) structure 20 obtained, over the course of time, it is possible to identify any differences between the “situations” of the structure 20 relating to the time intervals when the above-mentioned measurements are carried out; it is thereby possible, by comparing the data relating to the above-mentioned analyses, to obtain information on any damages and / or any degradation phenomena of the structure 20. For the interpretation of the measurements used for the OMA analyses, the values of the room temperature are needed.

[0191] The monitoring system 1 is such that the one or more accelerometric sensors 2 are connected to the corresponding data logger 3 according to a point-to-point scheme for the transmission to said data logger 3 of the measurements carried out by said accelerometric sensors 2.

[0192] In more detail, advantageously, the monitoring system 1 is such that the twenty accelerometric sensors 2 are connected to the data logger 3 according to a point-to-point scheme for the transmission to the data logger 3 of the measurements carried out by the same accelerometric sensors 2.

[0193] The above-mentioned connection is implemented by using the cable 4, connecting the data logger 3 to the accelerometric sensors 2. Each accelerometric sensor 2 is provided with two connectors, one for the input connection with the cable 4 and the other one for the output connection with the same cable 4.

[0194] The accelerometric sensors 2, by the cable 4, transmit to the data logger 3 the data relating to the measurements carried out by the same accelerometric sensors 2. By the cable 4, the data logger 3 communicates with the accelerometric sensors 2; in particular, the data logger 3, by using the cable 4, synchronizes the accelerometric sensors 2 and imparts the commands to the same accelerometric sensors 2. Moreover, by the cable 4, (as set forth above) the data logger 3 supplies the accelerometric sensors 2 by providing them with the electric power required for their operation.

[0195] The monitoring system 1 is such that the maximum number of the accelerometric sensors 2 that can be connected to a data logger 3 if said accelerometric sensors are in the third working condition is greater than the number, in particular is greater than one and a half times the number, of the accelerometric sensors 2 that can be connected to said data logger 3 if said accelerometric sensors 2 are in the first working condition.

[0196] In a monitoring system according to an embodiment of the present invention, if the accelerometric sensors (reference is made to accelerometric sensors according to an embodiment of the present invention that are of the variable configuration type), instead of being in the first working condition, which is characterized by a high sampling frequency, are in the third working condition, which is characterized by a lower sampling frequency, it is found that the number of such accelerometric sensors connectable to the data logger, other conditions being kept constant, may increase even in a significant manner.

[0197] The sampling frequency used by the accelerometric sensors affects, (the other conditions being kept constant) the maximum number of the accelerometric sensors (such as, for example, the accelerometric sensors 2) that are connectable to a data logger (such as, for example, the data logger 3). The convenience (for example) of using (where it is feasible) accelerometric sensors that are in the third working condition instead that in the first working condition is substantially to be able to significantly increase, other conditions being kept constant, the number of the accelerometric sensors that can be connected to only one data logger. However, such accelerometric sensors when they are in the third working condition are less suitable to measure in detail the accelerations due to dynamic actions of a very short duration, such as impacts, to which the monitored structure can be subjected, while being suitable to measure (con accuracy) those accelerations due to seismic actions.

[0198] The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2 comprised in said monitoring system 1 is made with MEMS (Micro Electro-Mechanical Systems) technology.

[0199] In more detail, advantageously, the monitoring system 1 is such that each of the accelerometric sensors 2 is made by using MEMS technology.

[0200] The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2, comprised in said monitoring system 1 is provided with at least one microprocessor that manages said accelerometric sensor 2, in particular that manages the communications with the data logger 3 to which said accelerometric sensor 2 is connected.

[0201] In more detail, advantageously, the monitoring system 1 is such that each of the accelerometric sensors 2 is provided with a microprocessor that manages said accelerometric sensor 2, in particular that manages the communications with the data logger 3 to which the same accelerometric sensor 2 connected.

[0202] The monitoring system 1 is such that one or more, in particular each, of the accelerometric sensors 2, according to the present first preferred embodiment each of the accelerometric sensors 2, comprised in said monitoring system 1 is provided with an internal clock that is updated by the data logger 3 to which said accelerometric sensor 2 is connected, according to a preset time frequency.

[0203] The monitoring system 1 comprises a single data logger 3.

[0204] The monitoring system 1 is such that the one or more accelerometric sensors 2 are connected to the corresponding data logger 3 by one or more cables, preferably by a single cable 4.

[0205] In more detail, the monitoring system 1 , is such that the twenty accelerometric sensors 2 are connected to the data logger 3 by the cable 4.

[0206] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 is connected to Internet; furthermore, the same data logger 3 transmits to at least one server, in particular to at least one virtual server 9 in the cloud, at least some data, in particular all the data, stored in said data logger 3, in particular in the first sector and in the second sector of the mass storage of said data logger 3.

[0207] In more detail, advantageously, the monitoring system 1 is such that the data logger 3 is connected to Internet; the data logger 3 transmits to a virtual server 9 in the cloud the data stored in the first sector and in the second sector of the mass storage of the same data logger 3.

[0208] The data transmission to the server 9 can be performed immediately after each storing carried out by the data logger 3 or after that the data logger 3 has carried out a preset number of storing.

[0209] The data logger 3, once it has stored in its mass storage the measurements relating to a preset number of significant events, transmits the above-mentioned data to the server 9. The number of the significant events that are stored before beginning the transmission to the server 9 varies as a function of the situations. Such a number can be equal to one, so that on the server 9 the data relating to a significant event are “immediately” available.

[0210] The data logger 3, once it has stored in its mass storage the measurements relating to a preset number of time intervals carried out by the accelerometric sensors 2 (connected to the data logger 3) with respect to which the same data logger 3 works with the “time-based” criterion, transmits the above-mentioned data to the server 9. Such a number can be equal to one, so that on the server 9 the data relating to every single time interval are “immediately” available.

[0211] The data logger 3, once it has stored in its mass storage the data relating to a relevant event, transmits, in particular, transmits as quickly as possible, the above-mentioned data to the server 9.

[0212] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 is remotely programmable and settable.

[0213] In more detail, advantageously, the monitoring system 1 is such that, the data logger 3 is remotely programmable and settable.

[0214] By the data logger 3, using the Internet connection, it is possible to set and to program the data logger 3; furthermore, it is possible, for example, to change the setting of the accelerometric sensors 2; in particular, it is possible, for each accelerometric sensor 2, to change the one or more first threshold values (the first threshold value if reference is made to the modulus of the acceleration vector), the one or more second threshold values (the second threshold value if reference is made to the modulus of the acceleration vector) and the one or more main threshold values (the main threshold value if reference is made to the modulus of the acceleration vector). Furthermore, it is possible to change, remotely, the configuration of the accelerometric sensors 2, in particular, it is possible to set each accelerometric sensor 2 so that the same accelerometric sensor 2 operates in the first working condition or in the second working condition or in the third working condition. Furthermore, it is possible to remotely re-program the data logger 3, such as, for example, in the case of updates of the software residing on the data logger 3.

[0215] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , for the Internet connection, comprises a modem, in particular a GSM modem, or is connected to a modem 7 external to said data logger 3, in particular to a GSM modem.

[0216] In more detail, advantageously the monitoring system 1 is such that, the data logger 3 for the Internet connection is connected to the GSM modem 7 by the connection cable 8.

[0217] Via such connection, the data logger 3 communicates with the server 9 and with the control center that manages the settings and, generally, the communications with the same data logger 3.

[0218] The monitoring system 1 is such that at least a data logger 3 synchronizes at least the same data logger 3 and the accelerometric sensors 2, connected to said data logger 3, by a procedure involving an Internet connection.

[0219] In more detail, advantageously, the monitoring system 1 is such that the data logger 3 synchronizes the same data logger 3 and the (twenty) accelerometric sensors 2, by a procedure involving Internet connection. Via Internet, the data logger 3 synchronizes itself and the accelerometric sensors 2, according to a preset time frequency, with the UTC (Universal Coordinated Time) time.

[0220] The monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 , in the case that the Internet connection temporarily stops, uses an internal clock, comprised in said data logger 3, to synchronize at least said data logger 3 and the one or more accelerometric sensors 2 connected to said data logger 3; additionally, starting from the recovery of the Internet connection, said data logger 3 begins to synchronize again at least said data logger 3 and the accelerometric sensors 2 connected thereto by said procedure involving the Internet connection.

[0221] In more detail, advantageously, the monitoring system 1 is such that, the data logger 3, in the case that the Internet connection temporarily stops, uses an internal clock, comprised in the data logger 3, to synchronize the same data logger 3 and the (twenty) accelerometric sensors 2 connected to the data logger 3. Moreover, starting from the recovery of the Internet connection, the data logger 3 begins to synchronize again the same data logger 3 and the (twenty) accelerometric sensors 2 connected thereto by the above-mentioned procedure involving the Internet connection.

[0222] According to a further implementation variation of the first preferred embodiment, not illustrated in the Figures, the monitoring system 1 is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 is able to store in an external device provided with mass storage at least some, in particular the entirety, of the data already stored in said data logger 3, in particular in the first sector and / or in the second sector of the mass storage of said data logger 3, during a determined operational period of said monitoring system 1 ; said external device is positioned in the proximity of said data logger 3, in particular adjacent to said data logger 3, and is such as to be easily accessible to make the data contained in the mass storage of said external device available.

[0223] In more detail, advantageously, according to the present implementation variation of the monitoring system 1 , the data logger 3 is able to store in an external device provided with a considerable mass storage all the data already stored in the first sector and / or in the second sector of the mass storage of the data logger 3, during a determined period (for example during one or more months) of operation of said monitoring system 1 ; said external device is positioned in the proximity of the data logger s, in particular adjacent to said data logger 3, and is such as to be easily accessible to make the data contained in the mass storage of said external device available. Such external device can be an external disk connected to the data logger 3.

[0224] According to the present implementation variation, the monitoring system 1 can be installed at a structure, such as a bridge, which is located at a place where there is no Internet access. In this case, since the communication between the data logger 3 and the corresponding server 9 is not possible, it is necessary to store in a device (such as an external disk), which is able to contain a significant amount of data, all the data stored in the mass storage of the data logger 3 over a determined period. The above- mentioned external disk is periodically manually retrieved by an operator, so as to make the data of the monitoring system 1 available.

[0225] According to the present implementation variation, the power supply of the monitoring system 1 , assuming that the public low-voltage power grid is not available in the proximity of the above-mentioned bridge, the power supply is provided by a power supply unit which provides (inter alia) the use of a photovoltaic panel.

[0226] The monitoring system 1 , according to the present implementation variation, is such that one or more, in particular each, of the one or more data loggers 3 comprised in said monitoring system 1 comprises a receiving unit or is connected to a receiving unit external to said data logger 3, said receiving unit being able to receive data relating to the time measurement, in particular said receiving unit being a GPS (Global Positioning System) unit; said receiving unit is adapted to synchronize, according to a preset frequency, the internal clock of said data logger 3.

[0227] In the Figs. 1 , 2 and 4 the monitoring system 1 installed at the structure 20 is illustrated. As illustrated, four accelerometric sensors 2 are positioned at the base 22 of the structure 20; furthermore, four accelerometric sensors 2 are positioned at each of four slabs 21 of the structure 20 (the structure 20 comprises seven slabs 21 ). The data logger 3, as set forth above, is positioned at the ground floor level, and it is easily accessible.

[0228] The monitoring system 1 was installed at the structure 20 to obtain information, as accurate as possible, relating to the response of the same structure 20 to a dynamic action, such as a seismic event or an impact and also to identify, over time, any variations of some characteristics of the structure 20 that can be obtained via OMA analysis, hence to get information about possible damages to the structure 20 during its operational life, in particular immediately after any relevant seismic events.

[0229] The monitoring system 1 preferably works in accordance with the first operating procedure described above.

[0230] As it has described above, the accelerometric sensors 2 are also adapted to carry out temperature measurements that are stored by the data logger 3 at least when said data logger 3 operates in accordance with the second and the third operating mode. According to a further implementation variation, not illustrated in the Figures, the monitoring system 1 is provided with specific temperature sensors that are independent from the accelerometric sensors 2; such temperature sensors are similar or equivalent to the temperature sensors 73 illustrated below. According to such implementation variation, the monitoring system 1 also comprises one or more sensor connection units, each of which is similar or equivalent to one of the sensor connection units 76 illustrated below; the one or more sensor connection units are adapted to connect one or more sensors, in particular temperature sensors, to the data logger 3. Referring to the Figures 6 to 9, a further implementation variation of the monitoring system 1 is described.

[0231] According to the present implementation variation, the monitoring system T, differs from the monitoring system 1 substantially in that the monitoring system T comprises thirty-two, and not twenty, accelerometric sensors 2.

[0232] The data logger 3, the modem 7 for the Internet connection, the supply unit 5 (which is connected, via the cable 11 ) to the public low-voltage power grid), the cables 6, the connection cable 8 and the cabinet 10 are equal (or substantially equal) to those used in the monitoring system 1 ; the cable 4’ is similar to the cable 4.

[0233] The accelerometric sensors 2, according to the present implementation variation, are in the second or in the third working condition, and they are never in the first working condition.

[0234] In more detail, according to the present implementation variation, the one or more accelerometric sensors 2 with respect to which the data logger 3 works with the “threshold-based” criterion, are in the third working condition and not in the first working condition.

[0235] The sampling frequency of the accelerometric sensors 2 that are in the third working condition, is less than the sampling frequency of the accelerometric sensors 2 that are in the first working condition. This allows, other conditions being kept constant, in particular the data logger 3 being kept constant, to increase also in a significant manner the number of the accelerometric sensors 2 that can be connected to a single data logger, such as the data logger 3. Such possibility can be very advantageous in many cases. As indicated in the Figures 6 to 9, the monitoring system T, according to the present implementation variation, comprises thirty-two (and not twenty) accelerometric sensors 2; in this manner, it is possible to monitor all the slabs 21 of the structure 20 and not only four of the seven slabs 21 of the same structure 20.

[0236] By using the accelerometric sensors 2 that are in the third working condition and in the second working condition, the measurements carried out in accordance with the first operating procedure, with the second operating procedure, with the third operating procedure and with the fourth operating procedure can be used both to derive information in the case of seismic events, and to derive information on the “situation” of the monitored structure 20, while being understood that, in accordance with such operating procedures, using accelerometric sensors that have a sampling frequency less than that of the first working condition, the accelerations relating to dynamic actions due to seismic events can be accurately measured, but the response of the structure to the dynam ic actions of a very short duration, such as an impact, cannot be accurately described, which dynamic actions are in any case detected.

[0237] The monitoring system T, in particular the data logger 3, is able to work according to the above-mentioned four operating procedures described above; it is understood that, any period of the operational life of the monitoring system 1 being set’, during said period only one of the above-mentioned four operating procedures is active. The monitoring system T, in particular the data logger 3, may also work according to the “on command” operating procedure.

[0238] In the monitoring system T, the data logger 3, in accordance with the first operating procedure, works most of the time with the “threshold-based” criterion with the (thirty-two) accelerometric sensors 2 that are in the third working condition; the data logger 3, furthermore, both within preset time intervals, and when a relevant event occurs, works with the “threshold-based” criterion with sixteen accelerometric sensors 2 (indicated in the Figures 8 and 9 with 2c) that are in the third working condition; furthermore, the data logger 3 works with the “time-based” criterion with the other sixteen accelerometric sensors 2 (indicated in the Figures 8 and 9 with 2b) that are in the second working condition.

[0239] In the monitoring system T, the data logger 3, in accordance with the second operating procedure, works most of the time with the “thresholdbased” criterion with respect to the (thirty-two) accelerometric sensors 2 that are in the third working condition; the data logger 3, in addition, in preset time intervals, works with the “threshold-based” criterion with respect to the sixteen accelerometric sensors 2 (indicated in the Figures 8 and 9 with “2c”) that are in the third working condition and with the “time-based” criterion with respect to the other sixteen accelerometric sensors 2 (indicated in the Figures 8 and 9 with “2b”) that are in the second working condition.

[0240] In the monitoring system T, the data logger 3, in accordance with the third operating procedure, works with the “threshold-based” criterion with reference to all the (thirty-two) accelerometric sensors 2 that are in the third working condition.

[0241] In the monitoring system T, the data logger 3, in accordance with the fourth operating procedure, works most of the time with the “threshold-based” criterion with the (thirty-two) accelerometric sensors 2 that are in the third working condition, and, in preset time intervals it works with the “time-based” criterion with the (thirty-two) accelerometric sensors 2 that are in the second working condition or in the third working condition.

[0242] Also in the case of the monitoring system T the first operating procedure is the preferred operating procedure, since it allows to carry out measurements from which it is possible to obtain both information relating to the response of the monitored structure (the structure 20 subjected to a dynamic action, such as (for example) a seismic action, and information relating to the dynam ic characterization of the structure 20. The first operating procedure further allows having the information on the dynamic characterization of the structure 20 even immediately after that the same structure 20 has immediately a relevant dynamic action.

[0243] As illustrated above with reference to the monitoring system 1 , also in the case of the monitoring system T the operating procedure with which the data logger 3 operates may change over time; in particular, the above- mentioned four operating procedures can alternate during the operational life of the monitoring system T; this allows optimizing the performance of the same monitoring system T even when the needs and the situation of the structure 20 change over time.

[0244] With reference to the Figures 10 ato13, a monitoring system 61 in accordance with a second preferred embodiment of the present invention is illustrated.

[0245] The monitoring system 61 , in accordance with a second preferred embodiment of the present invention, is used for monitoring a bridge 90; the monitoring system 61 comprises a data logger 63 and a plurality of (in particular, twenty-one) accelerometric sensors 62 connected to the data logger 63; each of said accelerometric sensors 62 is a variable configuration accelerometric sensor.

[0246] The monitoring system 61 is such that each of the twenty-one accelerometric sensors 62 is a variable configuration accelerometric sensor such that said accelerometric sensor 62, during the operational life of the monitoring system 61 , is able to work at least in a first working condition and in a second working condition.

[0247] The monitoring system 61 is continuously operating.

[0248] The monitoring system 61 is such that each of the (twenty-one) accelerometric sensors 62 (comprised in the same monitoring system 61 ) is a variable configuration accelerometric sensor such that said accelerometric sensor 62, during the operational life of said monitoring system 61 , is able to operate, in addition to the first and second working conditions, also in a third working condition. The monitoring system 61 , beside the (twenty-one) accelerometric sensors 62 and the data logger 63, comprises a cable 64 connecting the data logger 63 to the accelerometric sensors 62, a modem 67 for the Internet connection (external to the data logger 63) connected to the same data logger 63 by a connection cable 68, and a power supply unit 65 that, by using a photovoltaic panel 71 , provides the required electric power to the data logger 63 (by a supply cable 66), to the modem 67 (by a supply cable 66) and to the cable 77, which supplies three sensor connection units 76, described herein below; the modem 67 for the Internet connection is a GSM modem. The data logger 63, via the cable 64, provides to the accelerometric sensors 62 also the electric power required for their operation.

[0249] The supply unit 65, the data logger 63, the modem 67 and other electrical equipment required for the operation of the monitoring system 61 (not illustrated in the Figures) are located inside a cabinet 70 arranged in the proximity of one of the two shoulders 93 of the bridge 90. In the Figures, inside the cabinet 70, for ease of illustration, only the data logger 63, the supply unit 65 and the modem 67 are depicted.

[0250] The monitoring system 61 according to the present second preferred embodiment has components that are similar to those already described with reference to the monitoring system 1 and that, in order not to burden the description, are therefore not described in detail again. Furthermore, the operating modes and the operating procedures relating to the monitoring system 61 are equal or similar to those already described with reference to the monitoring system 1 .

[0251] The monitoring system 61 differs from the monitoring system 1 mainly in that comprises twenty-one accelerometric sensors 62 instead of the twenty accelerometric sensors 2, in that the power supply is provided (instead of by the public low-voltage power grid) by means of a photovoltaic panel 71 , and in that the monitoring system 61 comprises, besides the accelerometric sensors 62, a plurality of other sensors (different from the accelerometric sensors 62), a plurality of sensor connection units 76 and a supply cable 77 for the sensor connection units 76, as best specified herein below. According to the present second preferred embodiment, the monitoring system 61 comprises three sensor connection units 76.

[0252] The monitoring system 61 is able to monitor the health status of the bridge 90 at which it is installed; the monitoring system 61 , in addition, is able to monitor the bridge 90 in the case that applicate dynamic actions of a considerable intensity are applied thereto, such as impacts due to motor vehicles, or seismic actions.

[0253] The monitoring system 61 comprises one or more sensor connection units 76, each of which is adapted to connect one or more further sensors 72, 73, 74, other than the accelerometric sensors 62, to one of the one or more data loggers 63 comprised in said monitoring system 61 .

[0254] In more detail, advantageously, the monitoring system 61 comprises three sensor connection units 76, each of which is adapted to connect further sensors 72, 73, 74, other than the accelerometric sensors 62, to the data logger 63.

[0255] The monitoring system 61 comprises, besides the (twenty-one) accelerometric sensors 62, the following further sensors: three sensors 72 (inclinometers) to measure, relative to the vertical direction, slope of the plane to which the base of the above-mentioned sensor 72 is integral (which, for ease of explanation, is assumed as substantially horizontal), three sensors 73 (temperature sensors) for measuring the temperature of the environment, and a sensor 74 (hydrometer) for measuring the water level of a canal 91 flowing below one of the two spans of the deck 95.

[0256] The sensor connection units 76 located between the first and the second accelerometric sensor 62 is connected to two sensors 72 (inclinometers) and to a sensor 73 (temperature sensor). The sensor connection units 76 located between the seventh and the eighth accelerometric sensors 62 is connected to two sensors 72 (inclinometers), to a sensor 73 (temperature sensor) and to a sensor 74 (hydrometer). The sensor connection units 76 located between the thirteenth and the fourteenth accelerometric sensors 62 is connected to two sensors 72 (inclinometers) and to a sensor 73 (temperature sensor).

[0257] Each of such further sensors 72, 73, 74 is connected to the corresponding sensor connection units 76, which is connected via the cable 64 to the data logger 63. The above-mentioned sensors 72, 73, 74 carry out the measurements continuously, according to preset sampling frequencies. The above-mentioned sensors 72, 73, 74, by the corresponding sensor connection units 76, transmit to the data logger 63, the measurements carried out.

[0258] The monitoring system 61 is such that the data logger 63 is connected to the Internet by the GSM modem 67 that is external to the data logger 63 and that is connected to said data logger 63; the data logger 63 transmits to the server 69, which is a virtual server in the cloud, the data stored in the mass storage of the data logger 63, provided by the accelerometric sensors 62.

[0259] In addition, the data logger 63, once it has stored in its mass storage a preset number of data, relating to a given time interval, provided by the sensors 72, 73, 74 (different from the accelerometric sensors 62) connected to the three sensor connection units 76, transmits the above-mentioned data to the server 69. On the server 69, the latter data are processed by specific algorithms that, according to the case, can generate warnings and alarms.

[0260] The monitoring system 61 is such that at least one, in particular each, of the one or more sensor connection units 76 is directly supplied by a low- resistance power supply cable 77.

[0261] In more detail, advantageously, the monitoring system 61 is such that each of the three sensor connection units 76 is directly supplied by the low- resistance power supply cable 77. The cable 77 is supplied by the power supply unit 65.

[0262] As set forth above, the monitoring system 61 is installed at a bridge 90; the bridge 90 comprises two shoulders 93, with its corresponding base, a central pier 94 with its corresponding base, and a deck 95. The pier 94 is located in the proximity of a road 92 passing beneath one of the two spans of the bridge 90; a canal 91 flows beneath the other span of the bridge 90.

[0263] As illustrated, at the base of each of the two shoulders 93 and at the base of the pier 94, an accelerometric sensor 62 is positioned; on top of each of the two shoulders 93 and on top of the pier 94, two accelerometric sensors 62 are positioned; at each of the two spans of the deck 95, six accelerometric sensors 62 are positioned. Moreover, on top of each of the two shoulders 93 and on top of the pier 94, a sensor 73 and two sensors 72 are positioned; at the span of the bridge 90 beneath which the canal 91 floes, the sensor 74 measuring the water level is arranged.

[0264] The (nine) accelerometric sensors 62 that are arranged at the shoulders 93 and the pier 94 are in a first working condition and carry out the measurements according to a first sampling frequency by using first filters for processing the signals; such first sampling frequency ranges between 500 Hz and 1000 Hz, preferably is equal to about 1000 Hz.

[0265] The (twelve) accelerometric sensors 62 that are arranged at the deck 95 are in a second working condition and carry out the measurements in accordance with a second sampling frequency by using second filters for processing the signals; such second sampling frequency is of about 200 Hz.

[0266] In the Figures 12 and 13, with reference to the first operating procedure, the accelerometric sensors 62 that are in the first working condition are illustrated, indicated with “62a” and the accelerometric sensors 62 that are in the second working condition, indicated with “62b”. The monitoring system 61 is installed at the bridge 90, to obtain information relating to the response of the same bridge 90 to a seismic event and also to an impact, (such as an accidental impact of a motor vehicle at the pier 94) and also to identify, over time, any variations of some characteristics of the bridge 90, hence to get information about possible damages to the bridge 90 during its operational life, and, in particular, immediately after a relevant event, such as a seismic event or a significant impact. The monitoring system 61 is installed at the bridge 90 also for monitoring the water level of the canal 91 .

[0267] The monitoring system 61 is such that the data logger 63 preferably operates in accordance with the first operating procedure described above, or also in accordance with the second operating procedure described above.

[0268] For the monitoring system 61 , at least many of the considerations with regard to the use of the first operating procedure, the second operating procedure, the third operating procedure, the fourth operating procedure and the “on command” operating procedure described above with reference to the monitoring system 1 and the monitoring system T remain valid.

[0269] With reference to the figures 14 to 17, a monitoring system 111 according to a third preferred embodiment of the present invention is illustrated.

[0270] The monitoring system 111 according to a third preferred embodiment of the present invention is used for monitoring am industrial complex comprising two structures 130a, 130b; the monitoring system 111 is such that it comprises two data logger 1 13, a plurality of (in particular, thirty-six) accelerometric sensors 112 connected to the two data logger 113; each of said accelerometric sensors 112 is a variable configuration accelerometric sensor.

[0271] In more detail, sixteen accelerometric sensors 112 are connected to a data logger 113, and twenty accelerometric sensors 112 are connected to the other data logger 113.

[0272] The monitoring system 111 is such that each of the (thirty-six) accelerometric sensors 112 is a variable configuration accelerometric sensor such that said accelerometric sensor 112, during the operational life of the monitoring system 111 , is able to work at least in a first working condition and in a second working condition.

[0273] The monitoring system 111 is continuously operating.

[0274] The monitoring system 111 is such that each of the (thirty-six) accelerometric sensors 112 is a variable configuration accelerometric sensor such that said accelerometric sensor 112 is able to operate, in addition to the first and second working conditions, also in a third working condition.

[0275] The monitoring system 111 , besides the thirty-six accelerometric sensors 112 and the two data logger 113, comprises, for each of the two data logger 113, a cable 114a connecting the same data logger 113 to the corresponding accelerometric sensors 112, a modem 117 (which is a GSM modem) for the Internet connection (external to the above-mentioned data logger 113) connected to the above-mentioned data logger 113 by a connection cable 118, and a power supply unit 115 that also comprises a uninterruptible power supply; such power supply unit 115 is connected via the cable 121 to the public low-voltage power grid; to the above-mentioned power supply unit 115, the above-mentioned data logger 113 and the above- mentioned modem 117 are connected, by two cables 116 (power supply cables).

[0276] Each of the two data loggers 113, via the corresponding cable 114a, provides to the accelerometric sensors 112 connected to the same data logger 113 also the electric power required for their operation.

[0277] For each of the two data loggers 113, the supply unit 115, the same data logger 113, the modem 117 and the other electrical equipment required for the operation of the monitoring system 111 (not illustrated in the Figures) are located inside a cabinet 120 arranged at the ground floor, in an easily accessible position. In the Figures, inside each of the two cabinets 120, for ease of illustration, only the data logger 113, the supply unit 115 and the modem 117 contained in the above-mentioned cabinet 120 are depicted.

[0278] The monitoring system 111 has components that are similar to those already described with reference to the monitoring system 1 and that, in order not to burden the description, are therefore, not described in detail again. Furthermore, the operating modes and the operating procedures relating to the monitoring system 111 are equal, or substantially equal, to those already described with reference to the monitoring system 1 .

[0279] In particular, each of the two data loggers 113, each of the two modems 117 and each of the two power supply units 115 are similar respectively to the data logger 3, the modem 7, the power supply unit 5 described above.

[0280] The monitoring system 111 comprises a plurality of data loggers 113; one or more accelerometric sensors 112 are connected to each of said data loggers 113; said data loggers 113 are mutually connected; one of said data loggers 113 is the master data logger; the other one or more data loggers 113 are the slave data loggers.

[0281] In more detail, advantageously, the monitoring system 111 comprises two data loggers 113; sixteen accelerometric sensors 112 are connected to one of the two data loggers 113, twenty accelerometric sensors 112 are connected to the other data logger 113; the two data loggers 113 are mutually connected. The data logger 113, to which the sixteen accelerometric sensors 112 are connected, is the master data logger; the other data logger 113, to which the twenty accelerometric sensors 112 are connected, is the slave data logger.

[0282] The monitoring system 111 is such that the master data logger 113 synchronizes the slave data logger 113, thus synchronizing all the (thirty-six) accelerometric sensors 112 comprised in said monitoring system 111.

[0283] All the accelerometric sensors 112 have the same first threshold values, the same second threshold values, and the same main threshold values.

[0284] The monitoring system 111 is such that the master data logger 113, also via the one or more slave data loggers 113, manages all the accelerometric sensors 112 comprised in said monitoring system 111 , so that one or more, in particular each, of the data loggers 113 comprised in said monitoring system 111 operates, at least during a determined period, in particular during the whole operational life of said monitoring system 111 , in accordance with the first operating procedure, or in accordance with the second operating procedure, or in accordance with the third operating procedure, or in accordance with the fourth operating procedure, or in accordance with the “on command” operating procedure.

[0285] In more detail, the monitoring system 111 , according to the present third preferred embodiment, is such that the master data logger 113, also via the slave data logger 113, manages all the (thirty-six) accelerometric sensors 112, comprised in said monitoring system 111 , so that each of the two data loggers 113 operates, at least during a determined period, in particular during the whole operational life of said monitoring system 111 , in accordance with the first operating procedure, or in accordance with the second operating procedure, or in accordance with the third operating procedure, or in accordance with the fourth operating procedure, or in accordance with the “on command” operating procedure.

[0286] The data logger 113 master is such that it, also by the slave data logger 113, operates in an equivalent manner to the operational manner of a data logger (such as, for example, the data logger 3 or the data logger 63) that is the only data logger of a monitoring system.

[0287] The monitoring system 111 is such that each of the two data loggers 113 is connected to Internet by the corresponding GSM modem 117 that is external to the same data logger 113 and that is connected to said data logger 113; said data logger 113 transmits to the server 119, which is a virtual server in the cloud, the data stored in the mass storage of the data logger 113, provided by the accelerometric sensors 112 connected to said data logger 113.

[0288] The monitoring system 111 is such that the connection between the two or more data loggers 113 is implemented by one or more cables, preferably by a single cable 114b.

[0289] In more detail, the monitoring system 111 is such that the connection between the two data loggers 113 is implemented by the cable 114b.

[0290] For the monitoring system 111 , all the considerations regarding the use of the first operating procedure, the second operating procedure, the third operating procedure, the fourth operating procedure, the “on command” operating procedure described above with respect to the monitoring systems 1 and 61 remain valid.

[0291] The monitoring system 111 also comprises a signal repeater 122 in that the distance between two consecutive accelerometric sensors 112, in a case (in more detail, the distance between the tenth and the eleventh accelerometric sensors 112 connected to the data logger 113 slave) is excessive.

[0292] The monitoring system 111 is such that it comprises one or more signal repeaters 122 or one or more groups of signal repeaters arranged between an accelerometric sensor 112 and another accelerometric sensor 112 or arranged a data logger and an accelerometric sensor.

[0293] In more detail, advantageously, the monitoring system 111 is such that it comprises a signal repeater 122 arranged between the tenth and the eleventh accelerometric sensor 112 connected to the slave data logger 113.

[0294] The monitoring system 111 is such that one or more, in particular each, of said one or more signal repeaters 122 consists in an accelerometric sensor that is in the working condition of a repeater at which said accelerometric sensor does not perform any measurements, in particular, does not perform any acceleration measurements, but receives the signal, regenerates it, and retransmits it to the direction of the data logger 113 to which it is connected.

[0295] In more detail, advantageously, the monitoring system 111 is such that the signal repeater 122 consists in an accelerometric sensor (equal to any one of the accelerometric sensors 112) that is the working condition of repeater at which said accelerometric sensor does not perform any measurements, in particular does not perform any acceleration measurements, but receives the signal, regenerates it, and retransmits it to the direction of the data logger 113.

[0296] The possibility of the accelerometric sensors to be in the working condition of repeater is advantageous also for the management of the production of the same accelerometric sensors and for the management of the warehouse of the above-mentioned accelerometric sensors. In fact, the “role” of each accelerometric sensor, i.e., the role of an actual accelerometric sensor (performing acceleration measurements) or the role as a signal repeater, is assigned, at the time of installation of the monitoring system, without the need to provide or install different devices depending on the roles they perform within the monitoring system.

[0297] The monitoring system 111 is installed at the structures 130a, 130b

[0298] The structure 130a is made of reinforced concrete and comprises, in addition to columns, beams, and shear walls, three floor slabs 131 (including the cover slab) and portions of the foundations 133.

[0299] Four accelerometric sensors 112 are positioned at each of the three floor slabs 131 ; four accelerometric sensors 112 are positioned at the above- mentioned portions of the foundations 133.

[0300] The structure 130b comprises columns, a cover deck 132, comprising beams and tiles, and portions of the foundations 133.

[0301] Ten accelerometric sensors 112 are positioned at the base of the columns 131 and ten corresponding accelerometric sensors 112 are positioned on top of such columns 131 .

[0302] The two structures 130a, 130b are monitored together by a single monitoring system 111 , in order to have temporally mutually related information.

[0303] The monitoring system 111 is installed at the two structures 130a, 130b to measure their response to a seismic event and also to identify, over time, any variations of some characteristics of the same structures 130a, 130b, hence also to identify any damages to those during their operational life, and in particular after a relevant event.

[0304] The monitoring system 111 , in particular the two data loggers 113, during one or more periods of the operational life of the monitoring system 111 , in particular during the whole operational life of the monitoring system 111 , can operate preferably according to the first operating procedure or also in accordance with the second operating procedure, described above. It is understood that each of the two data loggers 113, during one or more periods of the operational life of the monitoring system 111 , in particular during the whole operational life of the monitoring system 111 , can also operate in accordance with the third operating procedure or the fourth operating procedure, described above, in addition to in accordance with the “on command” operating procedure.

[0305] In the Figures 16 and 17, with reference to the first operating procedure and the second operating procedure, the accelerometric sensors 112 that are in the first working condition are illustrated, indicated with “112a” and the accelerometric sensors 112 that are in the second working condition, indicated with “112b”.

[0306] According to possible implementation variations, the number of the accelerometric sensors 112b (especially those installed at the structure 130b) and their position (hence, the number of the accelerometric sensors 112a) can be different from those indicated in the Figures 16 and 17, following specific requirements relating to the monitoring project of the structures 130°, 130b.

[0307] According to a possible implementation variation, not illustrated in the Figures, of the monitoring system 111 , the single-floor structure arranged adjacent to the structure 130a has dimensions much greater than those of the structure 130b. Therefore, the length del cable 114a positioned at the above-mentioned single-floor structure has a length that is (much) greater than the length of the cable 114a relating to the alia structure 130b.

[0308] According to the present implementation variation, the monitoring system 111 comprises at least one additional supply module directly supplied, via a low-resistance cable, by the supply unit 115 (which supplies the data logger 113 in the proximity of the above-mentioned single-floor structure) supplying one of the two data loggers 113 comprised in said monitoring system 111 ; said at least one additional supply module is adapted to supply one or more accelerometric sensors 112 connected to said data logger 113 arranged at a distance from said data logger 113 such that the power supply supplied by said data logger 113 via the corresponding cable 114a is not sufficient to supply said one or more accelerometric sensors 112 anymore.

[0309] According to another implementation variation, not illustrated in the Figures, each of the two data loggers 113, comprised in the monitoring system 111 , is connected to Internet by a cable connected to the local wired network that is present in the above-mentioned industrial complex; in this case, the two modems 117 are not present in the monitoring system 111.

[0310] One or more, in particular each of the one or more (variable configuration) accelerometric sensors comprised in a monitoring system according to an embodiment of the present invention, by using specific algorithms, also acts as an inclinometer.

[0311] The accelerometric sensors used in the monitoring systems 1 , 61 , 111 described above are made with MEMS technology; however, it is possible that one or more, in particular each, of the one or more accelerometric sensors comprised in a monitoring system according to an embodiment of the present invention is made with technologies different from the MEMS technology.

[0312] A monitoring system according to an embodiment of the present invention may comprise at least one sensor for measuring the temperature of the environment where said sensor is located and / or at least one sensor to measure the displacements between two predefined points of a structure and / or at least one sensor to measure, with respect to the vertical direction, the slope of the plane to which the base of said sensor is integral, and / or at least one sensor to measure the stresses acting on a predefined portion of a structure and / or at least one sensor to measure the width of a crack present in a structure and / or other sensors.

[0313] A monitoring system according to an embodiment of the present invention may comprise, for example, in addition to the accelerometric sensors, one or more sensors for the measurement of environmental parameters, in particular for measuring air moisture, or carbon dioxide concentration in the air, or for detecting the presence of fumes, etc.

[0314] A monitoring system according to an embodiment of the present invention may comprise a sensor for the measurement of one or more hydraulic or hydrological parameters, in particular for measuring the water level and / or the water velocity of a watercourse.

[0315] In a monitoring system according to an embodiment of the present invention, one or more, in particular each, of the one or more data loggers comprised in said monitoring system can be preferably connected to Internet by a GSM modem or also by a satellite modem.

[0316] A monitoring system according to an embodiment of the present invention can be such that one or more, in particular each, of the one or more data loggers comprised in said monitoring system is connected to Internet by a cable connected to a local wired network.

[0317] There can be a monitoring system according to an embodiment of the present invention in which the one or more accelerometric sensors are such that said accelerometric sensors are connected to the corresponding data logger by a wireless technology.

[0318] A monitoring system according to an embodiment of the present invention may also comprise, in addition to one or more variable configuration accelerometric sensors, also one or more fixed configuration accelerometric sensors, such a term meaning that the configuration, in particular the working condition, of each of such accelerometric sensors cannot be varied, remotely, during the operational life of the above-mentioned monitoring system, or meaning that the configuration, in particular the working condition, of each of such accelerometric sensors cannot be varied neither remotely, nor by operating in situ, once the monitoring system is installed, or meaning that each of such accelerometric sensors has only one configuration, in particular can be in only one working condition.

[0319] In a monitoring system according to an embodiment of the present invention, one or more, in particular each, of the one or more accelerometric sensors comprised in the same monitoring system is a variable configuration accelerometric sensor such that said accelerometric sensor, during the operational life of said monitoring system, is able to operate, in addition to the first and second working conditions, also in one or more other working conditions, in particular in a third working condition or also in a third and in a fourth working conditions.

[0320] Herein below, a monitoring system is considered, where one or more, in particular each, of the one or more accelerometric sensors (such accelerometric sensors are variable configuration accelerometric sensors) connected to a data logger can be in a fourth working condition. Each of said one or more accelerometric sensors, when it is in the fourth working condition, carries out the acceleration measurements in accordance with a fourth sampling frequency by using one or more corresponding fourth filters for processing the signals. Such fourth sampling frequency, for example, can range between 60 Hz and 100 Hz.

[0321] The acquisitions taken at such a low frequency have, other parameters remain the same, a very limited noise; in some cases, this may be a relevant advantage.

[0322] The use of accelerometric sensors (which are variable configuration accelerometric sensors) that are in the fourth working condition can be implemented in the context of the five operating procedures described above, simply making so that one or more, in particular each, of the one or more accelerometric sensors that, a certain operating procedure being set, are (for example) in the second working condition, are, actually in the fourth working condition (and not in the above-mentioned second working condition). In alternative, it is possible to make one or more further operating procedures (in addition to the five operating procedures described above) in accordance with which, at least in preset time intervals, one or more of the accelerometric sensors are in the fourth working condition.

[0323] By using a monitoring system according to an embodiment of the present invention, the possibility to have of accelerometric sensors, which are of the variable configuration, allows optimizing the performance of the monitoring system, adapting them to the structure to be monitored and to the operative conditions, being in addition able, over time, to remotely change the procedures in accordance with which the above-mentioned monitoring system can operate. There can be a monitoring system according to an embodiment of the present invention, in which quale one or more, in particular each, of the accelerometric sensors (comprised in the monitoring system) is provided with an orientation sensor, in particular with an electronic compass, for, per determining the orientation of the above-mentioned accelerometric sensor in the horizontal plane.

[0324] It is understood that each of the monitoring systems described in the present description comprises, at the implementation level, some components not illustrated in the Figures attached to the present description; such components are, for example, the metallic (galvanized) pipes or pipes made of synthetic material within which the cables (for example, the cables 4, 4’, 64, 114) are arranged, the brackets for fastening the above-mentioned pipes, the inspection pits that may be present at ground level for routing the above-mentioned cables, the pits that may be present at ground level for positioning accelerometric sensors at the foundations, etc.

[0325] The accelerometric sensors comprised in a monitoring system according to an embodiment of the present invention can be such as to have preset characteristics regarding the degree of protection against the penetration by dusts and the water penetration, in particular they can be made according to preset values of the IP standards. Likewise, also the other components of the above-mentioned monitoring system, including the cables and the connectors, may have preset characteristics regarding the degree of protection against the penetration by dusts and the water penetration, in particular they can be made according to preset values of the IP standards.

[0326] With regards to the five operating procedures described above, the following can be generally stated.

[0327] The first operating procedure is the preferred operating procedure for monitoring structures (such as, for example, the structures of buildings and bridges).

[0328] In accordance with the first operating procedure, the monitoring system may provide data that allow identifying the response of the monitored structure to a dynamic action (such as, a seismic event or an impact) and data which, suitably processed, allow monitoring, in the SHM context, the “health status” of the structure, identifying over time the (possible) variations of such parameters, which can be due to damages and / or to degradation phenomena of the same structure. Moreover, in accordance with the first operating procedure, the monitoring system allows obtaining data relating to the situation of the structure even “immediately after” a relevant event (such as a significant seismic event).

[0329] The second operating procedure, which is similar to the first operating procedure, differs from the same first operating procedure mainly in that, in accordance with the second operating procedure, the monitoring system does not provide data relating to the parameters with respect to the dynamic identification of the monitored structure “immediately after” a relevant event (such as a seismic event), but provides data relating to the parameters regarding the dynamic identification of the monitored structure in given time intervals, identified according to a preset time frequency, during the operational life of the monitoring system.

[0330] In accordance with the third operating procedure, the monitoring system provides data that can be used to obtain information on the response of the monitored structure to a seismic event or an impact.

[0331] In accordance with the fourth operating procedure, the monitoring system provides data that can be used to obtain information both on the response of the monitored structure to a dynamic action, and on the parameters with respect to the dynamic identification of the monitored structure. The monitoring system, in accordance with the fourth operating procedure, may comprise a particularly significant number of accelerometric sensors with respect to which the data logger (to which said accelerometric sensors are connected), in preset time intervals, works with the “time-based” criterion.

[0332] The “on-command” operating procedure provides that “on-command”, in particular remotely, one intervenes in order to implement the second operating mode or the third operating mode. This allows at any time to activate measurements to obtain, by the use of suitable algorithms, information regarding the situation of the monitored structure.

[0333] By using the “on-command” operating procedure it is also possible to change the working condition of the accelerometric sensors. Therefore, it is found that, for example, in order to obtain the maximum information from the accelerometric sensors operating in the second working condition, all the accelerometric sensors comprised in the monitoring system can be temporarily configured in the second working condition.

[0334] In summary, the “on-command” operating procedure allows to temporarily configure the monitoring system, even in an “non-typical” manner, in order to temporarily obtain the highest number of data relating to a specific requirement deriving from a “specific” situation to be studied.

[0335] The determination of the operating procedure to be adopted for the one or more data loggers is part of the activities to design the monitoring (using the above-mentioned monitoring system) with respect to the structure that needs to be monitored.

[0336] In the case that the structure to be monitors is such, and / or the data required by the monitoring system are such that it is not necessary to use accelerometric sensors that are in the first working condition bur, for example, it is sufficient to use accelerometric sensors that are in the third working condition, the number of the accelerometric sensors that, other conditions being kept constant, can be connected to a data logger may be significantly increased; this is an advantage that, as set forth above, can be particularly significant in some cases.

[0337] The above-illustrated technical characteristics of the present monitoring system, as is clear, allow, singularly or in combination, to achieve one or more of the following advantages:

[0338] - with only one monitoring system information can be obtained, relating to the response of the monitored structure to a dynamic action, such, for example, a seismic event or an impact, and information can be obtained on the “situation” of the monitored structure;

[0339] - it is possible, after a relevant event, in particular “immediately after” a relevant event, to obtain data that may provide information relative to the situation of the monitored structure, also useful to identify any damages to the same structure;

[0340] - such monitoring system is configurable remotely so as to optimize the measurements to be carried out on the monitored structure;

[0341] - it is possible to remotely change the operating procedure of the one or more data loggers comprised in the monitoring system, so as to optimize the performance of the same monitoring system;

[0342] - the monitoring system comprises a single type of accelerometric sensor (variable configuration accelerometric sensor, in particular a variable working condition) that is able to perform, in an optimized manner, various function; this is very advantageous, besides to the project point of view and the performance of the monitoring system, also with reference to the production and the management of the accelerometric sensors;

[0343] - it is possible to make scalable monitoring systems; in fact, it is possible to make both monitoring systems equipped with a limited number of accelerometric sensors connected to a single data logger, and monitoring systems equipped with a significant number of accelerometric sensors (up to tens of accelerometric sensors) connected to various data loggers, which data loggers are mutually connected and are coordinated by the master data logger;

[0344] - it is possible to make monitoring systems comprising, in addition to accelerometric sensors, also sensors of other types, such as, for example, inclinometers, strain gauges, crack meters, displacement transducers, sensors to detect environmental parameters, sensors to detect hydrometric and hydrologic parameters.

[0345] The present invention is susceptible of evident industrial application. Those skilled in the art may further envisage a number of modifications and / or variations to be made to the same invention, while remaining within the scope of the inventive concept as broadly set forth herein. Furthermore, those skilled in the art may envisage further preferred embodiments of the invention comprising one or more of the features of the preferred embodiments illustrated above, in particular as set forth in the appended claims. Furthermore, it is also to be understood that all details of the present invention may be replaced by technically equivalent elements.

Claims

1. CLAIMS1. A monitoring system (1 ; 61 ; 111 ) for monitoring a structure, in particular said structure being the structure (20) of a building, a bridge, or another structure; said monitoring system (1 ) is characterized in that it comprises one or more data loggers (3) and one or more, in particular a plurality of, accelerometric sensors (2) connected to said one or more data loggers (3); one or more, in particular each, of said one or more accelerometric sensors (2) is a variable configuration accelerometric sensor.

2. The monitoring system according to claim 1 , characterized in that one or more, in particular each, of the one or more accelerometric sensors (2) comprised in said monitoring system (1 ) is a variable configuration accelerometric sensor such that said accelerometric sensor (2), during the operational life of said monitoring system (1 ), is able to operate at least in a first working condition and in a second working condition.

3. The monitoring system according to any one of the preceding claims, characterized in that said monitoring system (1 ) is continuously operating.

4. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more accelerometric sensors (2) comprised in the same monitoring system (1 ) is a variable configuration accelerometric sensor such that said accelerometric sensor (2), during the operational life of said monitoring system (1 ), is able to operate, in addition to the first and second working conditions, also in one or more other working conditions, in particular in a third working condition.

5. The monitoring system according to any one of the preceding claims, characterized in that at least one, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) measures the acceleration component according to an intrinsic axis of said accelerometric sensor (2), or measures the two acceleration components according to two intrinsic orthogonal axes of said accelerometric sensor (2), or measures thethree acceleration components related to the three intrinsic orthogonal axes of said accelerometric sensor (2), and transmits such measures to the data logger (3) to which said accelerometric sensor (2) is connected.

6. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ) processes and / or manages the measures carried out by each of the one or more accelerometric sensors (2) connected to said data logger (3) and is able to operate with at least one accelerometric sensor (2) that is in the first working condition and / or with at least one accelerometric sensor (2) that is in the second working condition and / or with at least one accelerometric sensor (2) that is in the third working condition.

7. The monitoring system according to any one of the preceding claims, characterized in that the configuration, in particular the working condition, of one or more, in particular of each, of the one or more accelerometric sensors (2), during the operational life of said monitoring system (1 ), is changed, in particular is changed one or more times every twenty-four hours, by the data logger (3) to which the same accelerometric sensor (2) is connected.

8. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) is provided with a first threshold value relating to one or two or three of the three acceleration components according to one axis or two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor (2), or is provided with a first threshold value relating to the modulus of the acceleration vector, or is provided with two first threshold values relating to two or three of the three acceleration components according to two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor (2), or is provided with three first threshold valuesrelating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor (2).

9. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) is provided with a second threshold value relating to one or two or three of the three acceleration components according to one axis or two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor (2), or is provided with a second threshold value relating to the modulus of the acceleration vector, or is provided with two second threshold values relating to two or three of the three acceleration components according to two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor (2), or is provided with three second threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor (2).

10. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) is provided with one main threshold value relating to one or two or three of the three acceleration components according to one axis or two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor (2), or is provided with one main threshold value relating to the modulus of the acceleration vector, or is provided with two main threshold values relating to two or three of the three acceleration components according to two orthogonal axes or the three intrinsic orthogonal axes, respectively, of said accelerometric sensor (2), or is provided with three main threshold values relating to the three acceleration components according to the three intrinsic orthogonal axes of said accelerometric sensor (2).11 . The monitoring system according to any one of the preceding claims,characterized in that one or more, in particular each, of the one or more accelerometric sensors (2) comprised in said monitoring system (1 ) is triaxial.

12. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more accelerometric sensors (2) comprised in said monitoring system (1 ) is provided with one or with two or with three first threshold values, in particular with three first threshold values, relating to the three intrinsic orthogonal axes of the same accelerometric sensor (2), is provided with one or with two or with three second threshold values, in particular with three second threshold values, relating to the three intrinsic orthogonal axes of said accelerometric sensor (2), and is provided with one or with two or with three main threshold values, in particular with three main threshold values, relating to the three intrinsic orthogonal axes of said accelerometric sensor (2).

13. The monitoring system according to any one of the preceding claims, characterized in that, in one or more, in particular in each, of the one or more accelerometric sensors (2) comprised in said monitoring system (1 ), the one or more second threshold values are not greater than, respectively, the one or more first threshold values, in particular are not greater than 70% of said one or more first threshold values; and in that the one or more main threshold values are greater than, respectively, said one or more first threshold values.

14. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ) is able to operate according to the “threshold-based” criterion and according to the “timebased” criterion.

15. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ) is able to operate according to the “threshold-based” criterion so that the same data logger (3)identifies, during the operational life of said monitoring system (1 ), when one or more of the one or more accelerometric sensors (2) connected to said data logger (3) are over-threshold relative to one or more of the one or more first threshold values or relative to one or more of the one or more second threshold values or relative to one or more of the one or more main threshold values, relating to said one or more accelerometric sensors (2).

16. The monitoring system according to any one of the preceding claims, characterized in that, in accordance with a first operating mode, one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), with respect to the one or more accelerometric sensors (2) connected to the same data logger (3), works with the “thresholdbased” criterion such that said data logger (3) stores in its mass storage, in particular in a first sector of said mass storage, the measurements carried out by said one or more accelerometric sensors (2) during each event whereby, following said event, the number of the accelerometric sensors (2) that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, a preset first design number.

17. The monitoring system according to claim 16, characterized in that said preset first design number is equal to one.

18. The monitoring system according to any one of the preceding claims, characterized in that it comprises one or more data loggers (3) and a plurality of accelerometric sensors (2); in that, in accordance with a second operating mode, one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), with respect to one or more accelerometric sensors (2) connected to the same data logger (3), works with the “threshold-based” criterion such that said data logger (3) stores in its mass storage, in particular in the first sector of said mass storage, the measurements carried out by said one or more accelerometric sensors (2) during each event whereby, following said event, the number of theaccelerometric sensors (2) that are over-threshold with respect to one or more of the corresponding one or more first threshold values is equal to, or greater than, the preset first design number; and in that, in accordance with said second operating mode, said data logger (3), concurrently, with respect to one or more other accelerometric sensors (2), connected to said data logger (3), works with the “time-based” criterion such that said data logger (3) stores in its mass storage, in particular in a second sector of said mass storage, the measurements carried out by said one or more other accelerometric sensors (2), independently of the values of the accelerations as measured by said one or more other accelerometric sensors (2).

19. The monitoring system according to any one of the preceding claims, characterized in that, in accordance with a third operating mode, one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), with respect to the one or more accelerometric sensors (2) connected to the same data logger (3), works with the “timebased” criterion such that said data logger (3) stores in its mass storage, in particular in the second sector of said mass storage, the measurements carried out by the one or more accelerometric sensors (2) connected to said data logger (3), independently of the values of the accelerations measured by said one or more accelerometric sensors (2).

20. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), when with respect to one or more accelerometric sensors (2) connected to said data logger (3) works with the “threshold-based” criterion, begins to store in its mass storage, in particular in the first sector of said mass storage, of the measurements carried out by said one or more accelerometric sensors (2), each time an event occurs, as a result of which the number of the accelerometric sensors (2) that are over-threshold with respect to one or more of the correspondingone or more first threshold values is equal to, or greater than, the preset first design number; said data logger (3), at the beginning of each storing, stores in said first sector of its mass storage the measurements carried out by said one or more accelerometric sensors (2) relating to a preset pre-trigger time interval.

21. The monitoring system according to claim 20, characterized in that said data logger (3), once the storage of said event has begun, the storage of the measurements carried out by said one or more accelerometric sensors (2), with respect to which said data logger (3) works with the “thresholdbased” criterion, continues for as long as the number of the accelerometric sensors (2) that are over-threshold with respect to one or more of the corresponding one or more second threshold values is equal to, or greater than, a preset second design number.

22. The monitoring system according to claim 21 , characterized in that said preset second design number is equal to one.

23. The monitoring system according to any one of the preceding claims 21 and 22, characterized in that said data logger (3) starts the end-of-storage step in its mass storage, in particular in said first sector of said mass storage, of the measurements carried out by said one or more accelerometric sensors (2) with respect to which said data logger (3) works with the “threshold-based” criterion when the number of the accelerometric sensors (2) that are overthreshold with respect to one or more of the corresponding one or more second threshold values is less than the preset second design number.

24. The monitoring system according to claim 23, characterized in that said data logger (3), in order to implement said end-of-storage step, during a preset post-trigger time interval that starts from the moment when said end- of-storage step starts, stores the measurements carried out by said one or more accelerometric sensors (2) with respect to which the data logger (3) works with the “threshold-based” criterion; said data logger (3), during saidpost-trigger time interval, controls that the number of the accelerometric sensors (2) that are over-threshold with respect to one or more of the corresponding one or more second threshold values is constantly less than said preset second design number; if, during said post-trigger time interval, the number of the accelerometric sensors (2) that are over-threshold with respect to one or more of the corresponding one or more second threshold values, at any given moment within said post-trigger time interval, is equal to, or greater than, said preset second design number, from said moment, the post-trigger time interval starts again; said data logger (3) ends the storage of the measurements relating to said event when the number of the accelerometric sensors (2) that are over-threshold, with respect to one or more of the corresponding one or more second threshold values, for an entire post-trigger time interval, remains less than said preset second design number.

25. The monitoring system according to any one of the preceding claims, characterized in that said first design number and said second design number are determined by taking into account all the accelerometric sensors (2) connected to one of the one or more data loggers (3) comprised in said monitoring system (1 ).

26. The monitoring system according to any one of the preceding claims, characterized in that said first design number and said second design number are determined by taking into account only the accelerometric sensors (2) with respect to which one of the one or more data loggers (3) comprised in said monitoring system (1 ) works with the “threshold-based” criterion.

27. The monitoring system according to any one of the preceding claims, characterized in that it comprises one or more data loggers (3) and a plurality of accelerometric sensors (2); and in that, during one or more periods of the operational life, in particular during the whole operational life, of said monitoring system (1 ), one or more, in particular each, of the one or moredata loggers (3) comprised in said monitoring system (1 ), in accordance with a first operating procedure, operates in accordance with the second operating mode both within preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and when an event occurs such that the number of the accelerometric sensors (2) that are overthreshold with respect to one or more of the corresponding one or more main threshold values is equal to, or greater than, a preset third design number; furthermore, the same data logger (3) operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system (1 ).

28. The monitoring system according to claim 27, characterized in that said preset third design number is equal to one.

29. The monitoring system according to any one of the preceding claims, characterized in that it comprises one or more data loggers (3) and a plurality of accelerometric sensors (2); and in that, during one or more periods of the operational life, in particular during the entire operational life, of said monitoring system (1 ), one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), in accordance with a second operating procedure, operates in accordance with the second operating mode in preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system (1 ).

30. The monitoring system according to any one of the preceding claims, characterized in that, during one or more periods of the operational life, in particular during the entire operational life, of said monitoring system (1 ), one or more, in particular each, of the one or more data loggers (3) comprised insaid monitoring system (1 ), in accordance with a third operating procedure, operates in accordance with the first operating mode.31 . The monitoring system according to any one of the preceding claims, characterized in that, during one or more periods of the operational life, in particular during the entire operational life, of said monitoring system (1 ), one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), in accordance with a fourth operating procedure, operates in accordance with the third operating mode in preset time intervals, in particular in preset time intervals spaced apart according to a preset time frequency, and operates in accordance with the first operating mode during the remaining portion of said one or more periods of the operational life, in particular during the remaining portion of the operational life, of said monitoring system (1 ).

32. The monitoring system according to any one of the preceding claims, characterized in that, in accordance with an “on-command” operating procedure, one or more, in particular each, of the one or more data loggers (3), upon command, in particular a remote command, operates, in one or more time intervals having a preset duration, in accordance with the second operating mode or the third operating mode.

33. The monitoring system according to any one of the preceding claims, characterized in that one or more of, in particular all, said operating procedures, during the operational life of the monitoring system (1 ), may be changed via remote communication with one or more of the one or more data loggers (3) comprised in said monitoring system (1 ).

34. The monitoring system according to any one of the preceding claims, characterized in that to one or more, in particular to each of the one or more accelerometric sensors (2), by the data logger (3) to which the same accelerometric sensor (2) is connected, the corresponding working condition, in particular the first working condition or the second working condition or thethird working condition, is assigned on command, in particular on a remote command.

35. The monitoring system according to any one of the preceding claims, characterized in that at least one or more, in particular each, of the one or more accelerometric sensors (2) is able to operate in certain working conditions whereby the same accelerometric sensor (2) is able to perform acceleration measurements according to certain sampling frequencies to which one or more specific filters for processing signals are associated.

36. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more accelerometric sensors (2) is able to perform temperature measurements.

37. The monitoring system according to claim 35, characterized in that, each of the one or more accelerometric sensors (2), when in the first working condition, performs the acceleration measurements according to a first sampling frequency by using one or more corresponding first filters for processing signals.

38. The monitoring system according to claim 35, characterized in that each of the one or more accelerometric sensors (2), when in the second working condition, performs the acceleration measurements in accordance with a second sampling frequency by using one or more corresponding second filters for processing signals.

39. The monitoring system according to claim 35, characterized in that each of the one or more accelerometric sensors (2), when in the third working condition, performs the acceleration measurements according to a third sampling frequency by using one or more corresponding third filters for processing signals.

40. The monitoring system according to claim 37, characterized in that said first sampling frequency is above 300 Hz, in particular above 500 Hz, preferably is about 1000 Hz.

41. The monitoring system according to claim 38, characterized in that said second sampling frequency is less than 200 Hz, in particular than 150 Hz, preferably said second sampling frequency has a value of about 100 Hz.

42. The monitoring system according to claim 39, characterized in that said third sampling frequency ranges between 150 Hz and 300 Hz.

43. The monitoring system according to any one of the preceding claims, characterized in that the one or more accelerometric sensors (2) are connected to the corresponding data logger (3) according to a point-to-point scheme for the transmission to said data logger (3) of the measurements carried out by said accelerometric sensors (2).

44. The monitoring system according to any one of the preceding claims, characterized in that said monitoring system (1 ) is such that the maximum number of the accelerometric sensors (2) that can be connected to a data logger (3) if said accelerometric sensors (2) are in the third working condition is greater than the number, in particular is greater than one and a half times the number, of the accelerometric sensors (2) that can be connected to said data logger (3) if said accelerometric sensors (2) are in the first working condition.

45. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) is made with MEMS technology.

46. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) is provided with at least a microprocessor that manages said accelerometric sensor (2), in particular that manages the communications with the data logger (3) to which said accelerometric sensor (2) is connected.

47. The monitoring system according to any one of the preceding claims,characterized in that one or more, in particular each, of the accelerometric sensors (2) comprised in said monitoring system (1 ) is provided with an internal clock that is updated by the data logger (3) to which said accelerometric sensor (2) is connected, according to a preset time frequency.

48. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the accelerometric sensors comprised in said monitoring system is provided with an orientation sensor, in particular with an electronic compass, for determining the orientation of said accelerometric sensor in the horizontal plane.

49. The monitoring system according to any one of the preceding claims, characterized in that it comprises a single data logger (3).

50. The monitoring system according to any one of the preceding claims 1 to 48, characterized in that it comprises a plurality of data loggers (113); one or more accelerometric sensors (112) are connected to each of said data loggers (113); said data loggers (113) are connected to each other; one of said data loggers (113) is the data logger master; the other one or more data loggers (113) are the data logger slave.51 . The monitoring system according to claim 50, characterized in that the data logger (113) master synchronizes the one or more data loggers (113) slave, thereby synchronizing all the accelerometric sensors (112) comprised in said monitoring system (111 ).

52. The monitoring system according to any one of the preceding claims 50 and 51 , characterized in that the data logger (113) master, also by the one or more data loggers (113) slave, manages all the accelerometric sensors (112) comprised in said monitoring system (111 ), so that one or more, in particular each, of the data loggers (113) comprised in said monitoring system (111 ) operates, at least during a certain period, in particular during the entire operational life of said monitoring system (111 ), in accordance with the first operating procedure, or in accordance with the second operatingprocedure, or in accordance with the third operating procedure, or in accordance with the fourth operating procedure, or in accordance with the “on-command” operating procedure.53 The monitoring system according to any one of the preceding claims 50 to 52, characterized in that the connection between the two or more data loggers (113) is enabled by one or more cables, preferably by a single cable (114b).54 The monitoring system according to any one of the preceding claims, characterized in that the one or more accelerometric sensors (2) are connected to the corresponding data logger (3) by one or more cables, preferably by a single cable (4).55 The monitoring system according to any one of the preceding claims, characterized in that the one or more accelerometric sensors are connected to the corresponding data logger by a wireless technology.

56. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ) is connected to the Internet; and in that the same data logger (3) transmits to at least one server, in particular to at least one virtual server (9) in the cloud, at least some of the data, in particular all the data, stored in said data logger (3), in particular in the first sector and in the second sector of the mass storage of said data logger (3).

57. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ) is remotely programmable and configurable.

58. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers comprised in said monitoring system is connected to the Internet bya cable connected to a local wired network.

59. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), for the connection to the Internet, comprises a modem, in particular a GSM modem, or is connected to a modem (7) that is external to said data logger (3), in particular to a GSM modem.

60. The monitoring system according to any one of the preceding claims, characterized in that at least one data logger (3), synchronizes at least the same data logger (3) and the accelerometric sensors (2), connected to said data logger (3), by a procedure involving a connection to the Internet.61 . The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), in the event that the Internet connection is temporarily interrupted, uses an internal clock, comprised in said data logger (3), to synchronize at least said data logger (3) and the one or more accelerometric sensors (2) connected to said data logger (3); and in that, starting from the resumption of the Internet connection, said data logger (3) starts synchronizing again at least said data logger (3) and the accelerometric sensors (2) connected thereto by said procedure involving a connection to the Internet.

62. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ), comprises a receiving unit or is connected to a receiving unit that is external to said data logger (3), said receiving unit being adapted to receive data relating to the time measurements, in particular said receiving unit being a GPS unit; said receiving unit is able to synchronize, according to a preset frequency, the internal clock of said data logger (3).

63. The monitoring system according to any one of the preceding claims, characterized in that one or more, in particular each, of the one or more data loggers (3) comprised in said monitoring system (1 ) is able to store in an external device provided with mass storage at least some of, in particular all, the data already stored in said data logger (3), in particular in the first sector and / or in the second sector of the mass storage of said data logger (3), during a certain operation period of said monitoring system (1 ); said external device is located at said data logger (3), in particular adjacent to said data logger (3), and is such that it can be easily accessed to make the data contained in the mass storage of said external device available.

64. The monitoring system according to any one of the preceding claims, characterized in that it comprises one or more signal repeaters (122) or one or more groups of signal repeaters arranged between an accelerometric sensor (112) and another accelerometric sensor (112) or between a data logger and an accelerometric sensor.

65. The monitoring system according to claim 64, characterized in that one or more, in particular each, of said one or more signal repeaters (122) consists in an accelerometric sensor, which is in the working condition of repeater at which said accelerometric sensor does not perform any measurements, in particular does not perform any acceleration measurements, but receives the signal, regenerates it, and retransmits it to the direction of the data logger (113) to which it is connected.

66. The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor (73) for the measurement of the temperature of the environment where said sensor (73) is located.

67. The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor for the measurement of the displacements between two predefined points of a structure.

68. The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor (72) for the measurement, relative to the vertical direction, of the slope of the plane to which the base of said sensor (72) is integral.

69. The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor for the measurement of the stresses acting on a predefined portion of a structure.

70. The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor for the measurement of the width of a crack present in a structure.71 . The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor for the measurement of environmental parameters, in particular for measuring air moisture, or carbon dioxide concentration in the air, or for detecting the presence of fumes.

72. The monitoring system according to any one of the preceding claims, characterized in that it comprises at least one sensor (74) for the measurement of one or more hydraulic or hydrological parameters, in particular for measuring the water level and / or the water velocity of a watercourse.

73. The monitoring system according to any one of the preceding claims 66 to 72, characterized in that it comprises one or more sensor connection unit (76), each of which is able to connect one or more additional sensors (72, 73, 74), other than the accelerometric sensors (62), to one of the one or more data loggers (63) comprised in said monitoring system (61 ).

74. The monitoring system according to claim 73, characterized in that at least one, in particular each, of the one or more sensor connection unit (76) is directly powered by a low-resistance power supply cable (77).

75. The monitoring system according to any one of the preceding claims, characterized in that said monitoring system (111 ) comprises at least oneadditional supply module that is directly powered, by a low-resistance cable, by the supply unit (115) that supplies one of the one or more data loggers (113) comprised in said monitoring system (111 ); said at least one additional supply module is able to supply one or more accelerometric sensors (112) connected to said data logger (113) arranged at a distance from said data logger (113) such that the power supply provided by said data logger (113) via the corresponding cable (114a) is no longer sufficient to supply said one or more accelerometric sensors (112).

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