Accelerations
Measurement of the vibration response at instrumented points.
Technical guide · Structural monitoring
Dynamic monitoring and vibration response of structures
Observing over time how a structure responds to vibrations from service and the environment.
Dynamic monitoring acquires accelerations with accelerometers and follows the structure's response over time; modal analysis is one of the tools used to process these data.
What it observes
Bridges, viaducts, tunnels and buildings are subject to vibrations from traffic, use and environmental actions. Dynamic monitoring measures these vibrations and follows how they evolve.
Parameters such as natural frequencies and mode shapes can be derived from the data and any changes over time observed, to be interpreted in the context of the structure.
What it can provide
Response in service
Behaviour of the structure under traffic and operating conditions.
Modal parameters over time
Frequencies and mode shapes followed over time through modal analysis.
Changes in behaviour
Observing changes in dynamic response, to be technically interpreted.
Asset management support
Information supporting decisions on infrastructure in service.
Attention thresholds
Where the system provides for them, thresholds agreed with the client.
How it is set up
The layout depends on the structure and the question; no single scheme suits every structure.
- 01Question and objective
- 02Choice of measuring points
- 03Accelerometer installation
- 04Acquisition over time
- 05Processing and dynamic identification
- 06Interpretation and reporting
Dynamic monitoring observes the response over time; modal analysis is one of its processing tools, not a synonym.
Related methods
Further topics in the monitoring cluster and the comparison with point-in-time bridge diagnostics.
Modal analysis
Identifying frequencies and mode shapes.
Static monitoring
Slow phenomena: deformations and cracks.
SHM sensor networks
Designing and managing the system.
Integrated bridge diagnostics
Point-in-time surveys of structures.
Frequently asked questions
- What does dynamic monitoring measure?
- The structure's vibrations, typically as accelerations measured by accelerometers, observed over time.
- How does it differ from modal analysis?
- Modal analysis identifies frequencies and mode shapes; dynamic monitoring follows the response over time and may use modal analysis to process the data.
- Which structures is it used on?
- Structures and infrastructure such as bridges, viaducts, tunnels and buildings, including historic ones, when the question concerns vibration response.
- Does it replace diagnostic surveys?
- No. NDT surveys provide point-in-time knowledge of materials and geometry; monitoring observes behaviour over time. They can be combined when needed.