Monitoring, is a very common term used in all fields today. But what does surveillance mean? The general answer is that we monitor a "system". Why do we need to monitor it? To check if the system is changing over time and to be prepared for future changes. For example, let us talk about monitoring our health. What do we do when we feel sick? Of course, we go to the doctor. And what does the doctor do? He examines us and prescribes a medicine based on the diagnosis. Is that enough? No, it is advisable that our doctor follows our development until we feel better and we can adapt to our environment.
But the system we will talk about next is not able to adapt to changes in the environment. Steel structures, for example, will rust if we do not take the appropriate measures, and lose their strength as a result. So how do we know that our structure will remain functional and not collapse in the next earthquake, for example. There's no way to know without monitoring. So someone has to monitor our structure on a regular basis. In short, we monitor its health. We are not doctors, of course, but the structure is our patient.
Structural engineering is all about probabilistic analysis and design. Neither the load nor the resistance of the material are exact values; we are constantly dealing with variables. Therefore, it is important to monitor the good behavior of our structure so that when it is stressed by extreme loads, it does not fail or lose its stiffness or reach a state close to collapse at any time during its service life.
What do we monitor in a structure? When is it important to check the health of a structure?
The following points are key during the monitoring of a structure:
1. Detect damage to structural elements.
2. Classify the types of damage
3. Locate them within a structural scheme
4. Determine the severity of the damage
How to detect damage to a structure?
Damage can be detected by records of special devices that emit signals via optical fibers, or devices with electronic sensors and accelerometers. Using these recordings, it is possible to detect changes in the natural frequency of buildings caused by the loss of stiffness of the assembly, or to determine that deformations exceed allowable limits, or even to determine that a structure is deforming without a dynamic load being applied. All of this data is valuable and allows us as structural engineers to make the right decisions immediately to prevent collapse or major damage.
