Structural supervision
The term building monitoring (BÜ), also building monitoring , refers to the continuous metrological monitoring and engineering evaluation of the structures of buildings .
Area of application and objective
The predominant area of application of the structure monitoring results from the increasing age of structures and from the increasing demands on the load-bearing capacity and durability of a structure.
The objectives of such monitoring are:
- Recording the general condition or need for repair of structures;
- Damage prevention and service life prediction of a structure
- The reduction of maintenance and renovation costs .
Another area of application is the monitoring of structures during a construction project, for example in tunnel construction projects and deeper excavations. The settlement or movement of the surrounding structures is recorded here so that measures can be taken if necessary. In such a case, one speaks of geodetic construction supervision or geodetic monitoring. Further areas of application for geodetic construction supervision:
- tunnel
- Dams
- Retaining walls
- Buildings and historical structures
- Roads and railways
- bridges
- Landslides
- Mining
As already mentioned, the aim of such monitoring is to identify dangerous subsidence, movements or landslides at an early stage in order to take countermeasures if necessary.
operation area
The main areas of application are bridge structures , wide-span hall structures and roofs . There is also building monitoring for multi-storey car parks or underground garages if damage due to the effects of chloride is to be expected. In addition, there is a risk of the surface coating being abraded in the curve areas or on ramps as a result of horizontal braking and / or ball forces, so that their protective effect can no longer be guaranteed.
If a monitoring system is used to record damage from the exposure classes carbonation and chloride attack , so-called corrosion monitoring is usually used. Since these two types of damage cause corrosion after the reinforcement has been depassivated, it is necessary to record the corresponding electrochemical parameters.
These are:
- electrical concrete resistance
- electrochemical potential
- Amperage
Since the resistance and the current strength are particularly influenced by temperature and humidity, the temperature and the humidity or the concrete humidity must also be recorded at the same time. The current state of the art provides several types of sensors for this. On the one hand there are the anode conductors and on the other hand the multi-ring electrodes. Although these sensors detect different quantities, their measuring principle is the same; There is a staggered arrangement of several individual anodes, so that the user has the opportunity, after evaluating the data on the active anodes with regard to corrosion phenomena, to immediately deduce the exact depth of penetration of the damage and, if necessary, to make a prognosis for the remaining service life of the construction.
execution
Characteristic values on the component such as deformation and expansion , temperature , humidity , cracks and vibrations are recorded by measurement . Modal and acoustic emission analysis are special methods of measurement. The evaluation of the measurement results is usually automated using modern data processing .