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- Englisch (20) (entfernen)
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- Cultural heritage (6)
- Non-destructive testing (6)
- Historic masonry (5)
- Radar (5)
- Concrete (3)
- Damage (3)
- Flood (3)
- Masonry (3)
- Non-destructive testing in civil engineering (3)
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Organisationseinheit der BAM
ONSITEFORMASONRY is a research project funded by the European Commission under the 5. Framework Programme 1998-2002 in the Thematic Programme: Energy, Environment and Sustainable Development and the Key Action: The City of Tomorrow and Cultural Heritage.
The main objective of the project is the development and improvement of methodologies for the evaluation of the structure of historic masonry Cultural Heritages. For effective restoration and conservation of historic buildings, a detailed assessment of the structural safety and physical damages of the masonry structure is required. Therefore, typical masonry damages and the most frequent pathologies in each region have been identified and summarised in a catalogue of problems and damages. Selected non-destructive (NDT) and minor-destructive (MDT) techniques are performed by the partners including the development of software packages for fast and automated data analysis. The strategy for an effective and useful combination of different NDT and MDT methods will be worked out considering the results of case studies and taking into account the experiences of the consortium members. Recommendations and guidelines for the application of the integrated methodologies will be developed in close co-operation with end-users.
Strategies and methodologies for the assessment of historic masonry structures based on non-destructive and minor-destructive testing methods were developed in the European Research Project ONSITEFORMASONRY and were successfully applied to assess the structure and material properties of selected structural elements in the Altes Museum in Berlin-Mitte.
For the planning of a broad reconstruction within the framework of a master plan concerning the whole of Museum Island in Berlin, several questions arose which are also typical for other historic structures in general, thus the Altes Museum was chosen as a pilot site for the validation of non-destructive testing methods.
Ultrasound sensors should be embedded into concrete for monitoring concrete properties. These new longitudinal wave sensors with a center frequency of 60 kHz were examined regarding their suitability for ultrasonic measurements in concrete structures in terms of emission characteristics, sensitivity and frequency ränge.
For the measurement of the radiation patterns, the sensors were embedded vertically and horizontally in concrete cylinders. The directivity pattern was measured using a laser vibrometer.
The sensitivity of the sensor was determined in water using different sensors of the same type. It shows changes in the signal amplitude as well as variations in the frequency ränge for different transmitter-receiver combinations.
The attenuation of the concrete affects the achievable resolution of the measurements and thus, the maximum possible spacing of the sensors within a concrete element. Experimental tests helped optimizing the distances with respect to the required resolution and the effort of embedding the sensors. The signal attenuation in the concrete was measured in the frequency ränge of 60 kHz in response to various degrees of reinforcement and grain size. For this purpose, the sensors were cast at different distances in the specimens studied. The recorded Signals were evaluated for their amplitude and frequency spectrum.