SAMCO Final Report 2006 F09 Report on Bridge Management
The “ordinary” cases – the common situation for bridge management.
It is essential that it is specified from the beginning, what the problem is and how it is handled by the current inspections with or without NDT-methods and sampling and that the costs for this are listed. This will usually result in a number of alternative strategies being evaluated based on the latest inspections report and may involve monitoring as a new, alternative strategy.
The accuracies of the different strategies and their associated damage predictions should be determined as well, since this will show how safe or reliable a decision would be.
The service life, maintenance and warranty of the proposed monitoring systems should also be taken into consideration.
The monitoring of an existing structure should only be decided, after the following points have been met:
An initial inspection has been carried out with NDT-mapping and sampling. This will determine the relevant inspection areas.
The monitoring positions have been determined (precise positions and num- ber of parameters to be measured).
The requirements to the sensors have been described as accuracy of the sensor, temperature range, service life and signal range, but also as the ac- curacy of the “translated” signal (e.g. degree of damage, change in corrosion risk, effect on service life).
A plan for sampling and on-site, temporary monitoring or NDT-mapping dur- ing the installation of the monitoring system has been set up (e.g. sampling of concrete dust from the drilled hole for installing sensors in order to determine chloride content, control measurements of optical fibre deformation sensors).
Rules have been described for the periodic checking of the monitoring system
g. failure of cables, deterioration or malfunction of corrosion risk sensor checked by NDT-equipment). This should at least be carried out at each in- spection, where access to the structure is available.
The incorporation of the monitoring data in the reporting from the visual in- spection and the NDT-measurements during the special inspections has been described.
A report or manual which describes exactly what the monitoring system in- cludes, with drawings and photographs of the different sensors positions, list of sensor types, translation of the raw data into real parameters etc.). This shall be available at the end of the monitoring installation and should be such that independent controllers (or other suppliers) can check the system and even take over the responsibility of the systems performance.
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