TY - CONF A1 - Helmerich, Rosemarie A1 - Moldenhauer, Laura A1 - Voigt, Gerrit A1 - Köppe, E. T1 - Considerations for identification of moisture in building materials using Bluetooth (R) N2 - The vulnerability of low-quality concrete of some bridges to ageing and deterioration while they are exposed to environmental conditions during their service life, influence of growing population and climate changes, is a well-known effect and requires survey. For survey, the development of a low cost, cost-efficient sensor network to be embedded for continuous or attached to the surface for periodic monitoring is essential. Changing ground water conditions, flood or even leakage in fresh or disposal of waste water can lead to in-creased moisture content in building materials and structural elements as walls or floors. Moisture allows the transport of other adverse chemicals that might reduce the durability of structures. The paper presents a feasibility study about the capability of microwave modules as bluetooth® or ZigBee with frequency range at 2,4 GHz to create advanced Wireless Sensor Networks (WSN) for estimation and visualization of moisture distribution in infrastructure assets. It was found that the value of the received signal strength indication (RSSI) depends on the moisture content and can be the basis for the moisture distribution inside a massive structure. The microwave modules may be used to compose networks outside and inside of building materials or structural elements. The higher the number of connections between BLE modules, the more precise and the more distant information can be obtained from the network. Mesh networking was applied to increase the quantitative information. T2 - 9th International Conference on Bridge Maintenance, Safety and Management (IABMAS) CY - Melbourne, Australia DA - 09.07.2018 KW - Structural Health Monitoring KW - Moisture KW - Bluetooth PY - 2018 SN - 978-1-315-18939-0 SN - 978-1-138-73045-8 SP - 2752 EP - 2759 AN - OPUS4-50340 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Helmerich, Rosemarie A1 - Milmann, Boris A1 - Wöstmann, Jens T1 - Bond durability of CFRP-laminates on concrete bridges N2 - Trans-European corridors for transport of people and goods require strengthening of bridges to carry increased axle loads in terms of absolute axle loads and of their frequency. Most of the bridges along highways are reinforced or prestressed concrete bridges. Since the late 1990s, CFRP laminates have been applied to box girder and T-beam bridges to increase the overall capacity. Although regular inspections are carried out, no special method was available to test the bond condition of CFRP laminates after being in Service for more than ten years. The German Center of Competence in Civil Engineering is aware of this need and funded a research project to investigate the bond condition by means of advanced non-destructive testing (NDT). T2 - 31st Danubia-Adria Symposium on advances in experimental mechanics CY - Kempten, Germany DA - 24.09.2014 KW - Concrete bridges KW - Strengthening KW - Non-destructive testing KW - CFRP KW - Durability KW - Inspection PY - 2014 SN - 978-3-00-046740-0 SP - 1 EP - 2 AN - OPUS4-33116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 - Hong, Shuxian A1 - Lai Wai-Lok, Wallace A1 - Helmerich, Rosemarie A1 - Milmann, Boris ED - Biondini, F. ED - Frangopol, D.M. T1 - NDT-based monitoring of accelerated steel corrosion in concrete T2 - IABMAS 2012 - 6th International conference on bridge maintenance, safety and management CY - Stresa, Lake Maggiore, Italy DA - 2012-07-08 KW - Concrete KW - Reinforcement corrosion KW - Nondestructive testing KW - Ground penetration radar KW - Ultrasonic echo PY - 2012 SN - 978-0-415-62124-3 SN - 978-0-203-10338-8 SP - 1 EP - 8(?) PB - CRC Press CY - London, UK AN - OPUS4-29581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bien, J. A1 - Helmerich, Rosemarie ED - Jasienko, J. T1 - Theoretical and experimental analysis of historical bridges T2 - SAHC 2012 - 8th International conference on structural analysis of historical constructions CY - Wroclaw, Poland DA - 2012-10-15 KW - Historical bridges KW - Theoretical analysis KW - Experiments KW - Diagnostics PY - 2012 SN - 978-83-7125-216-7 SN - 0860-2395 VL - 1 SP - 45 EP - 63 PB - DWE CY - Wroclaw, Poland AN - OPUS4-26830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Helmerich, Rosemarie ED - Biondini, F. ED - Frangopol, D.M. T1 - Full scale fatigue testing of original truss members and connections T2 - IABMAS 2012 - 6th International conference on bridge maintenance, safety and management CY - Stresa, Lake Maggiore, Italy DA - 2012-07-08 KW - Existing bridges KW - Laboratory testing KW - Fatigue KW - Remaining service life KW - Weak details KW - Materials testing PY - 2012 SN - 978-0-415-62124-3 SN - 978-0-203-10338-8 SP - 8 pages PB - CRC Press CY - London, UK AN - OPUS4-29455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Friese, Martin A1 - Helmerich, Rosemarie A1 - Effner, Ute A1 - Mielentz, Frank ED - Frangopol, D. ED - Sause, R. ED - Kusko, C. T1 - Capabilities of non-destructive testing of RC structures - quality assurance for crack repair using ultrasonic echo T2 - IABMAS 2010 - Bridge maintenance, safety, management and life-cycle optimization CY - Philadelphia, PA, USA DA - 2010-07-11 KW - Zerstörungsfreie Prüfung KW - Ultraschall KW - Risse KW - Erfolgskontrolle Rissinjektion PY - 2010 SN - 978-0-415-87786-2 SP - 1524 EP - 1531 PB - CRC Press AN - OPUS4-22548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Helmerich, Rosemarie A1 - Milmann, Boris ED - Frangopol, D. ED - Sause, R. ED - Kusko, C. T1 - Contribution on non-destructive defect detection to bridge management T2 - IABMAS 2010 - Bridge maintenance, safety, management and life-cycle optimization CY - Philadelphia, PA, USA DA - 2010-07-11 KW - Ultrasonic measurement KW - Transversal waves KW - Bond defect KW - Defect detection KW - Concrete structures KW - Debonded area visualisation PY - 2010 SN - 978-0-415-87786-2 SP - 1 EP - 8(?) PB - CRC Press AN - OPUS4-22680 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -