Monitoring structural responses
A significant concern for a structure is the risk that it gets exposed to a loading condition that it is unable to support. The ability for a structure to carry a specific load is dependent upon the:
- current configuration
- materials
- condition of structure
- stability and capacity of the soil support elements
- presence of other loading
Although loads may be associated with a variety of inputs, the overall safety of a structural element can be related to its displacement capacity. Monitoring structural responses references measuring how and when a structural element moves, vibrates, tilts, twists, bends or is impacted.
Static and dynamic loads
Loads applied to a structure impart stresses, deformations and displacements. In general there are two types of loads; static and dynamic. In a static loading condition, the load is constant with respect to time. The dead weight of a structure is an example of a static load. Dynamic loads are external loads that vary with time and impart forces upon the structure that are also variable with time – this creates an interdependency between cause and effect. An example of a dynamic load is a flash flood with debris impacting the piers of a bridge.
Examples of dynamic loads
A dynamic load’s ability to influence a structure can be significant! Dynamic loads can come from a variety of sources including human activity, working machinery, construction work, collisions, collapse of a structural element, loss of soil support, and environmental inputs such as the wind or earthquakes.
The basis for monitoring structural responses
Any structure with defined characteristics such as mass distribution, stiffness component, and inherent dampening values will respond differently to different loading conditions. Alternatively, changes in a structure’s capacity to carry a given load will produce a different response to that same load.
Monitoring structural responses
When monitoring the dynamics of a structural element, profiles are created that characterize how the structure moves, vibrates, tilts, and deforms at rest and under load. These profiles are calculated from the actual responses of the structure and are based upon the principle that for a given load, a structure’s response will be the same of the structure’s capacity to carry the load is the same. If the structure’s capacity to carry a given load changes or a new loading condition is introduced – then the response of the structure will change and these changes can be detected by sensors.
Benefits of monitoring structural responses
The measurement and monitoring of structural responses provides valuable insight into what loads are acting upon the structure, how the structure is coping with these loads, and how these loads are influencing the structure’s behavior. Structural response monitoring fosters awareness and facilitates the safe and efficient operation of the structure by allowing users to make timely, data-driven decisions that are based upon the current condition for the structure. Monitoring structural responses provides the foundation for an enhanced management program that directly supports:
- Inspection and maintenance – Response monitoring fills in the gaps between periodic inspections by providing continuous trend data and critical measurements that are not discernible by periodic visual inspections.
- Real-time management – By continuously monitoring and reporting structural responses and environmental measurements, engineers have continuous awareness of their structures and can observe and react to immediate changes.
- Early detection – Monitoring structural responses is a broad method for monitoring the health of a structure, unlike other sensing methods that can only monitor specific points on a structure, structural response monitoring can detect conditions and states influencing the entire structure. This advanced detection capability enhances coverage and increases the opportunities for the early responses that can minimize property and casualty losses.
Our Internet-enabled structural monitoring products are easy to deploy and let users monitor structures in real-time with their phones or laptops, anywhere in the world.
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