TY - CONF A1 - Trela, Christiane A1 - Kind, Thomas A1 - Schubert, Marcus T1 - Detection of air voids in concrete by radar in transmission mode N2 - Air voids in concrete like honeycombs are one of the major concerns regarding quality assurance for the construction of infrastructure buildings like bridges or tunnels. This paper shows that voids in reinforced concrete walls or slabs can be detected by two standard ground coupled GPR antennas in transmission mode using a two-side zero-offset profiling configuration like in borehole radar applications. For the detection of voids only the amplitudes of the direct wave in transmission mode are evaluated. Even when the depth of the void can not be detected in this configuration, the major advantage of the zero-offset profiling in transmission mode is a lower interference with the surrounding reinforcement compared to a regular one-side reflection profiling. The capability of the two-side zero-offset profiling is demonstrated on a test specimen with a set of polystyrene balls of two different sizes representing voids like honeycombs in concrete. GPR measurements are realized by an automated scanning system in order to allow for a synchronous movement of the antennas. In transmission mode voids can be detected at greater depths compared to reflection mode, since the travel path of the direct wave is half as long. Another characteristic of the transmission mode is that the direct wave through the air voids is faster and arrives earlier than the direct wave in the surrounding concrete. Hence it can be separated from the strong reflection of the reinforcement. Finally the measurements in transmission mode are less sensitive to the antenna frequency and polarization than in reflection mode. T2 - IWAGPR 2015 - 8th International workshop on advanced ground penetrating radar CY - Firenze, Italy DA - 07.07.2015 KW - Radar KW - Zerstörungsfreie Prüfung KW - Ground penetrating radar KW - Transmission KW - Reinforced concrete KW - Honeycombs KW - Void detection KW - First arrival PY - 2015 SN - 978-1-4799-6495-6 DO - https://doi.org/10.1109/IWAGPR.2015.7292650 AN - OPUS4-34678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Trela, Christiane A1 - Wöstmann, Jens A1 - Kruschwitz, Sabine ED - Carlos Brebbia, T1 - Contribution of radar measurements to the inspection and condition assessment of railway bridges - case study at a historic masonry arch bridge in Olesnica/Poland N2 - Ground Penetration Radar (GPR) as a non-destructive (NDT)-method can be applied to obtain detailed information about the inner structure and condition of bridges without damaging the structure. In this paper the capabilities and limitations of the application of the fast inspection technique GPR will be demonstrated. In addition to GPR investigations, geoelectrical measurements, coring and petrophysical investigations have been carried out. The investigated railway bridge in Olesnica is a typical European masonry arch bridge (age, construction and span length). It shows typical damage to the masonry arches such as increasing salt concentration, destruction, material losses and longitudinal cracks. Radar measurements were carried out with two main objectives: (1) Identification of basic geometric dimensions of the bridge and identification of construction details; (2) Evaluation of the condition of the masonry, such as mechanical damage (e.g. cracks) or variation of the moisture content. Radar antennas of different frequencies (having different penetration depths) have been used to estimate the thickness of the walls. Because of the high attenuation in the inner masonry structure the measurements have not produced satisfying results, but the radar measurements have been successfully applied to investigate the moisture distribution in the masonry. These results have been verified by coring and through geoelectrical measurements. Cracks were studied at two testing areas at one wing wall of the bridge using an automatic 2D radar scanning system. The radar data were processed using advanced data processing tools like FT-SAFT reconstruction and data fusion. The processing sequence allowed the creation of high-resolution depth sections (C-Scans). KW - Ground Penetration Radar KW - Spectral induced polarization KW - Coring KW - Railway bridge KW - Non-destructive testing method KW - Condition assessment PY - 2008 SN - 978-1-84564-106-1 DO - https://doi.org/10.2495/HPSM080541 SN - 1743-3509 VL - 97 SP - 535 EP - 544 PB - WIT Press CY - Ashurst, Southampton, UK AN - OPUS4-17745 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bien, J. A1 - Kaminski, T. A1 - Trela, Christiane ED - Hyun-Moo Koh, ED - Dan M. Frangopol, T1 - Numerical analysis of old masonry bridges supported by field tests T2 - Bridge Maintenance, Safety, Management, Health Monitoring and Informatics - IABMAS 2008 CY - Seoul, South Korea DA - 2008-07-13 PY - 2008 SN - 978-0-415-46844-2 SP - 2384 EP - 2391 PB - CRC Press CY - Boca Raton AN - OPUS4-17749 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paasche, H. A1 - Wendrich, Astrid A1 - Tronicke, J. A1 - Trela, Christiane T1 - Detecting voids in masonry by cooperatively inverting P-wave and georadar traveltimes N2 - Collecting different geophysical data sets at the same object and site offers the opportunity to reduce uncertainties and ambiguities in data analysis and interpretation. To be effective, the different available data sets should be linked during the model-generation process, e.g. by cooperative inversion. In this study, we apply a recently developed zonal cooperative inversion approach based on fuzzy c-means cluster analysis to a non-destructive testing experiment. After briefly reviewing the fundamentals of the inversion strategy, we present a synthetic study investigating the potential of the method to detect air-filled voids in masonry by using ultrasonic and georadar traveltime data. Then, we present and discuss laboratory experiments including the results of cooperatively inverted ultrasonic and georadar traveltimes collected at a masonry test specimen. The geometry of the specimen is known and is thus an ideal test object for a first-time real application of the novel zonal cooperative inversion procedure. Compared to the results of separate inversions of ultrasonic and georadar traveltimes, the zonal cooperative inversion allows for an improved delineation of the size and position of the cavities. The P-wave and georadar velocities determined for the model regions corresponding to the cavities are also improved. KW - Non-destructive testing KW - Tomography KW - Traveltime KW - Cooperative inversion KW - Cluster analysis PY - 2008 DO - https://doi.org/10.1088/1742-2132/5/3/002 SN - 1742-2132 VL - 5 SP - 256 EP - 267 PB - IOP Publ. CY - Bristol AN - OPUS4-18815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Trela, Christiane A1 - Gil, Magdalena ED - Meßinger, J. T1 - Bodenuntersuchungen mit Georadar zum Auffinden von Grenzsteinen KW - Bodenuntersuchung KW - Georadar KW - Grenzsteine KW - Radar PY - 2010 SN - 0947-1944 VL - I SP - 7 EP - 14 PB - Dt. Geophysikalische Ges. CY - Potsdam AN - OPUS4-21836 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trela, Christiane T1 - Ergebnisse aus dem Teilprojekt der BAM: Bodenuntersuchungen mit Georadar zum Auffinden von Grenzsteinen T2 - Radar-Rundtischgespräch an der TU Bergakademie Freiberg, Institut für Geophysik CY - Freiberg, Germany DA - 2009-09-24 PY - 2009 AN - OPUS4-20120 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cruz, P.J.S. A1 - Topczewski, L. A1 - Fernandes, F.M. A1 - Trela, Christiane A1 - Lourenco, P.B. T1 - Application of radar techniques to the verification of design plans and the detection of defects in concrete bridges N2 - Non-destructive tests (NDT) are an essential tool used in special inspections to gather detailed information about the condition of a bridge. The inspection of bridge decks is a critical task, and, currently, can be successfully carried out using a wide range of NDT techniques. Nevertheless, some of these techniques are excessively expensive and time consuming. One of these techniques, the ground penetrating radar (GPR), has been used for some decades in the non-destructive inspection and diagnosis of concrete bridges. GPR is useful to find general information about the true position of reinforcement and tendon ducts, and check the quality of the construction and materials. A significant number of reinforced and prestressed concrete bridges are deteriorating at a rapid rate and need to be repaired and strengthened. During these rehabilitation processes, designers are often faced with a lack of original design plans and unawareness of the real position of reinforcement and tendon ducts. In this paper, three case studies of the use of GPR techniques for the inspection of concrete bridges are presented and analysed. The main aim of this research is to show the strong need and usefulness of these techniques, which can provide non-visible information about structural geometry and integrity required for strengthening and rehabilitation purposes. KW - Non-destructive tests KW - Ground penetrating radar KW - Tomography KW - Bridge condition assessment KW - Detection of defects PY - 2010 DO - https://doi.org/10.1080/15732470701778506 SN - 1573-2479 SN - 1744-8980 VL - 6 IS - 4 SP - 395 EP - 407 PB - Taylor & Francis CY - London AN - OPUS4-20144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kind, Thomas A1 - Feistkorn, Sascha A1 - Trela, Christiane A1 - Wöstmann, Jens T1 - Impulsradar für schadensfreie Kernbohrungen an Spannbetonbrücken N2 - Der Bedarf an Kernbohrungen in Stahlbetonbauwerken ist in den letzten Jahren durch die steigende Anzahl von Instandsetzungen und Ertüchtigungen unterschiedlicher Stahlbetonbauten stark gewachsen. Für die Durchführung einer Kernbohrung ist die Kenntnis der genauen Lage der vorgespannten Bewehrung notwendig, um diese für die Statik wichtigen Elemente nicht zu beschädigen. Das methodische Vorgehen für die schadensfreie Durchführung von Kernbohrungen wird am Beispiel einer ca. 1 m dicken Hohlkastenseitenwand der Karl-Carstens Brücke in Bremen gezeigt. Nach der Darstellung der Ausgangslage und der Aufgabenstellung werden die Schritte beschrieben, die zu einer erfolgreichen Durchführung der Aufgaben erforderlich waren. Hierbei steht die planmäßige Anwendung der zerstörungsfreien Untersuchungsmethode Impulsradar im Vordergrund. Das Vorgehen gliedert sich in vier Schritte: - Zunächst wurde eine Voruntersuchung durchgeführt, um festzustellen, ob sich die vorgespannte Bewehrung in den erwarteten Tiefen von bis zu 50 cm und unter den vorhandenen Bedingungen der Hohlkastenseitenwände mit dem Impulsradar detektieren lässt. - Nach der erfolgreichen Voruntersuchung wurden im zweiten Schritt die Bereiche der geplanten Kernbohrungen großflächig mit dem Impulsradar untersucht. - Anschließend konnte anhand der Messdaten die Lage der Bewehrung ermittelt und in einen Plan eingezeichnet werden, der im Maßstab 1:1 ausgedruckt wurde. Dieser Plan wurde positionsrichtig auf die Oberfläche der Hohlkastenwand geklebt. - Im letzten Schritt wurden dann gezielte Test- und Suchbohrungen durchgeführt, denen die eigentlichen Kernbohrungen folgten. Mit der im Plan dargestellte Bewehrungslage war die Voraussetzung für schadensfreies Bohren gegeben. So konnten die Kernbohrungen durchgeführt werden, ohne die vorgespannte Bewehrung zu beschädigen. KW - Zerstörungsfreie Prüfung KW - Impulsradar KW - Stahlbetonbrücke KW - Ertüchtigung KW - Kernbohrung KW - Schubnadeln KW - Spannglieder PY - 2009 DO - https://doi.org/10.1002/best.200900060 SN - 0005-9900 SN - 1437-1006 VL - 104 IS - 12 SP - 876 EP - 881 PB - Ernst CY - Berlin AN - OPUS4-20657 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trela, Christiane T1 - Application of ultrasonic and radar tomography for the investigation of the internal structure of masonry T2 - IIIrd Workshop of "NDT in Progress" CY - Prague, Czech Republic DA - 2005-10-10 PY - 2005 AN - OPUS4-11977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trela, Christiane T1 - Radartomografie zur Strukturuntersuchung an Betonbauteilen T2 - 6. Radarrundtischgespräch an der TU Freiberg im Institut für Geophysik CY - Freiberg, Germany DA - 2005-09-29 PY - 2005 AN - OPUS4-11071 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -