TY - CONF A1 - Wolf, Julia A1 - Milmann, Boris A1 - Helmerich, Rosemarie A1 - Köpp, Christian A1 - Mielentz, Frank A1 - Wiggenhauser, Herbert A1 - Kurz, J.H. A1 - Moryson, R.-M. A1 - Samokrutov, A. A1 - Alekhin, S. G. A1 - Alver, Ninel A1 - Sazak, H.-Ö. ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Ultrasound based monitoring system for concrete monolithic objects N2 - 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. T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 09.12.2013 KW - Ultrasound KW - Concrete KW - Monitoring system KW - Ultrasonic network KW - Embedded sensor PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 6 AN - OPUS4-29642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Milmann, Boris A1 - Helmerich, Rosemarie A1 - Köpp, Christian A1 - Wiggenhauser, Herbert A1 - Kurz, J.H. A1 - Moryson, R.M. A1 - Samokrutov, A. A1 - Alekhin, S. G. A1 - Alver, Ninel A1 - Sazak, H.Ö. T1 - An ultrasound monitoring system for concrete structures N2 - The research project "Ultrasonic Net for Concrete Monitoring (UNeCOM)" aims at developing a methodology for an embedded ultrasonic network for the condition assessment of infrastructure constructions. Civil engineering structures made of concrete, which are located in tectonically active regions or undergo special loading conditions, may require continuous monitoring. It is important to assess the condition of the building and its stability to recognise and classify the effect of a seismic event or evolving damage at early stages before failure occurs. Embedded ultrasonic sensors offer the possibility to detect changes in the material and degradation mechanisms from inside the structure in areas which are difficult or impossible to inspect otherwise. In contrast to conventional ultrasonic testing methods, where the concrete surfaces are scanned with ultrasound probes, this new approach uses sensors, which are embedded into concrete, eliminating the effect of variable coupling conditions between sensors and concrete. This method allows an integral detection of changes in the concrete structure, for example due to seismic activities, to detect mechanical impacts, as well as degradation of the material due to overloading. Such methods have great relevance especially for the monitoring of constructions like power plants, bridges, offshore structures and other structures with high technical safety requirements. The sensor network can be controlled remotely through the internet which is also being used for data transfer. The embedded sensor network is designed to monitor structural damage and concrete degradation globally with high sensitivity. T2 - Istanbul bridge conference 2014 CY - Istanbul, Turkey DA - 11.08.2014 KW - Ultrasound KW - Concrete KW - Monitoring PY - 2014 SN - 978-605-64131-6-2 SP - Paper 32, 1 EP - 9 AN - OPUS4-32028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -