The major part of the infrastructure has reached an age where the inspection and maintenance costs con- stitute the major part of the costs. Monitoring and inspection systems are used in a variety of industries to ensure safety and reduce costs by early detection of damage Such systems can also be applied to ex- isting civil engineering structures if the necessary probes are available for embedding.
Within a BRITE/EuRam project eight European partners developed an integrated monitoring system aiming the reduction of the inspection and maintenance costs as well as the traffic impairments. The important part of this project was related to development of different new sensors to be embedded in existing concrete structures as a part of the monitoring system. These sensors should register time to corrosion initiation, chloride content, humidity and pH.
Laboratory and on-site tests have been carried out. Based on the laboratory test calibration curves monitored on-site data have been translated. The system is being tested on-site on a highway bridge near Copenhagen with sensors installed during 2000 and 2001 in approximately 200 positions. The first results of on-site testing are now being ana- lyzed, and the suitability of the probes within the integrated monitoring system can be shown. The monitoring on-site will continue for the next five years and it should contribute to the further im- provement of the sensors. N
OVERVIEW OF THE SMART STRUCTURES PROJECT
The current development in structural monitoring is concentrated on the installation of permanently embedded sensors. Theses monitors continuously provide information on structures, for
? reducing the inspection costs,
? more reliable deterioration trends (frequent collection of data),
? more precise assessment of the conditions of the structures,
? input for undertaking preventative actions,
? input for defining maintenance/repair strategies,
? feedback on the effectiveness of repairs and
? evaluation of the need for further inspections and additional testing
During the SMART STRUCTURES - an interdisciplinary research project funded by the European Community - eight European partners developed and tested the necessary probes and sensors for moni- toring chloride, moisture, pH and corrosion risk in different depths and for strain, crack-widths, vibra- tion frequencies and amplitudes for use in existing concrete structures. These are integrated by an Inter- net-based software for collecting, storing and treating the monitoring data in order to produce an input to the bridge maintenance.
For field testing of the monitoring system, the Skovdiget-Bridge near Copenhagen in Denmark has been chosen both for convenient location and because different deterioration mechanisms are contemporarily active on the structure. In order to reach the desired objective of the research, the project was divided into 7 tasks:
1. State of the art survey pointing to requirements and system specifications for the integrated monitoring system from the end-user point of view,
2. Evaluation of the most relevant deterioration mechanisms for the structures with the parameters that may be measured on-site determining the critical levels of both the parameters of the models and of the corresponding measurable parameters,
3. Implementation of portable equipment to measure corrosion activity. This equipment may be used to support the current activity of monitoring and inspection of bridges,
4. Design, development, production and lab tests of a number of sensors to be installed on the structures to monitor their progressive deterioration,
5. Designing
