Methodology and Work Packages

Developments in the proposed project are designed as smart monitoring techniques that employ permanently installed technologies addressing mainly the following aspects:

• Competitiveness
• Simple application (installation, data interpretation, calibration capability)
• Stable long term behavior
• Minimally invasive mounting and installation (interchangeability, miniaturization, aesthetically appealing)
• Open for different sensor technologies (multi sensor platform)
• Integrated data analysis and interpretation methodologies (automatized procedures)

Taking these aspects into consideration, the focus of the monitoring system development is on small wireless sensor networks and autonomous wireless sensors based on platforms that (i) could be used in combination with any kind of low power sensors (Figure 1), (ii) provide self organizing and reorganizing network functionality, (iii) have very low power consumption with optimized soft- and hardware functionality and (iv) achieve sufficient methodologies for data analysis, data fusion and data reduction. Additionally, competitive sensors and sensor technologies (e.g. MEMS – Micro Electro Mechanical Systems) are developed or used, if they are already available on the market.


Figure 1: Wireless sensing systems
However, continuous monitoring of structures is not useful if just a large amount of data is recorded and stored without further adequate analysis. This is why often continuous monitoring is unappre-ciated. There is a lack of sufficient models for material and structural deterioration that take into account the data from continuous monitoring. In order to provide the practitioner in the field of cultural heritage with a tool which goes beyond the mere accumulation of data, but instead provides help in the sense of warnings (e.g. if damaging factor values increase) and recommendations for action (e.g. window opening/closing, ventilation on/off, heating on/off, etc.) data fusion and interpretation is implemented within the monitoring system. To this aim software will be developed which is:

• user friendly, to be used by practitioners in the field,
• modular (modules for specific questions arising at the object to be monitored and sensor combinations),
• open source, for maximum transparency,
• open for extensions and new modules, also from other research groups.

The modularity and open source concepts are most important for providing a dynamic tool, which can and will be updated and broadened continuously with new research results, both from partners within this project team and from other research groups with their special expertise.
Type of preferentially measured parameters and of monitored material
A number of building materials (wood, brick and stone masonry, mortars, plasters, terracotta, pig-ment layers, etc.) and material assemblies typical for historic structures will be monitored for better investigation of structural damage and environmental pollution effects. With respect to the aspects of smart monitoring techniques defined above, for some applications there are presently no suffi-cient sensor technologies available. This is especially true for chemical attack due to gases or salts, for the measurement of moisture content inside a material and for the measurement of air flow at low speed inside buildings. For this reason new sensor technologies are investigated and tested with these purposes (especially air flow sensors for low air speed, humidity and temperature sensors, salt sensors as well as acoustic emission sensors are in focus). In particular the following parameters will be measured/monitored:

• temperature & humidity (in environment and materials using resistive sensors air humidity sensors and miniaturized MEMS)
• air velocity (especially for low air speed measurement inside buildings)
• strain and crack opening (strain gauges etc.)
• acoustic emissions
• vibration, inclination (MEMS)
• ambient light, UV light, (with regard to paintings and pigments)
• chemical attack due to gases (e.g. HCl, O3, SO2, NH3 NOx, etc.) or salts (chlorides, sulphates etc.)

In situ application

Evaluation of methodology/technology used
Measures of physical, chemical and mechanical material and environmental parameters during repeated monitoring on samples and specimens in varying environmental conditions are aimed to simulate and better understand structural and material deterioration processes due to environment (Figure 2).

Figure 2: Interconnection between measurements, simulation and data evaluation

Based on previous experiences of the partners, physical models built in the lab will simulate the form of structural elements made of brick and stone masonry, with addition of plaster layers; com-ponent materials and masonry layout will be chosen in view to reproduce complex elements typical for historical structures. The main specimens used are of two types: the first type is aimed at evaluating the effectiveness of different NDT methods to quantitatively detect defects and inhomogeneities. Therefore these physical models will contain simulated defects such as voids, irregular mortar joints, inclusions, etc.
Continuous wireless monitoring will be done for temperature, air humidity, masonry humidity, resis-tivity and salt distribution.
The second type of specimens is used to evaluate the capacity of the NDT methods to detect the beginning of material and structural damage and its evolution over longer periods, by measuring mechanical and physical properties. Therefore in their asbuilt condition, these specimens will not contain simulated defects and after a first measurement campaign, they will be subjected to compressive tests. The NDT tests will be repeated at different load levels. Reliability and applicability of employed techniques to the specific cases of complex historic structures will be studied.
One objective of the project is the provision of methods and algorithms of data reduction and analysis for continuous monitoring of historic structures intended for preventive conservation. Therefore it is necessary to determine materials and deterioration models, considering the most important influences of environment (data fusion), that could be monitored by sufficient technologies.

Work Packages, leaders, and home organisation
Work Package	Work Package Leader	Organisation
WP 1: Management	Markus Krüger	USTUTT (MPA) (DE)
WP 2: Technical Guidance	Stefan Simon	RRL (DE)
WP 3: Monitoring Techniques	Markus Krüger	USTUTT (IWB) (DE)
WP 4: Modelling & Analysis	Alexandra Troi	EURAC (IT)
WP 5: Assessment & Comparative Testing	Camilla Colla	UNIBO (IT)
WP 6: Case Studies	Vlatka Rajčić	UNIZAG (HR)
WP 7: Dissemination & Exploitation	Michal Lukomski	PASc (PL)

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