SHM Structural Health Monitoring
- The Types
- Static SHM
- Dynamic SHM
- Enviromental SHM
“Static” structural monitoring is used for the control of slowly variable parameters during a significant period of observation to make perceive the trend. Generally, it is used for the control of cracks in buildings, with recording of environmental parameters. Data reading has settable frequency (eg. hourly, or more dense), with registration for a suggested period of at least an annuity. With static monitoring “absolute” and “relative” movements and rotations of the structure can be controlled in real time, with appropriate sensors that measure the variables related to the checks that you want to do.
Sensors are connected by cable or wireless network to the central acquisition provided of acquisition cards and PC for recording and analyzing data. System has a remotely data transmission device to send data daily at our engineers for the analysis of the same.
“Dynamic” monitoring allows identification of the vibrational characteristics – and in any case of dynamic nature – of the structure under investigation (frequencies, natural modes, damping).
A dynamic monitoring system is composed of sensors (mainly accelerometers), by a system of acquisition and transmission of data and by a database for data collection and structural diagnosis.
Acquisitions may involve accelerations, velocities or displacements of some points indicative of the structure. Recordings can be performed at regular time intervals, continuously recorded at low sampling rates or enabled to overcome a preset “threshold” level.
Data acquired are processed to relate the level of vibration to the limits suggested or imposed by the regulations. UNI 9916 sets out the methodology to follow during the measurements, data processing and evaluation of the effects of vibration on the building, and identifies possible sources of vibration and factors that influence the structural response of buildings to the vibrations.
In historic buildings and museums, control of environmental parameters is necessary in order to prevent the main phenomena of degradation, such as detachment, subflorescenze and efflorescence, discoloration, expansion and shrinkage, cracking and chemical-biological processes.
A single control unit records the signals from the sensors and allows you to monitor in real time the system from your PC, wherever you are. Systems can be wired or wireless.
The main environmental parameters are monitored: temperature, relative humidity, air velocity, light, carbon dioxide.