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 - 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 - GEN A1 - Wendrich, Astrid A1 - Trela, Christiane A1 - Krause, Martin A1 - Maierhofer, Christiane A1 - Wöstmann, Jens A1 - Milmann, Boris ED - Mazal, P. T1 - Application of ultrasonic and radar tomography for the investigation of the internal structure of masonry T2 - 3rd International Workshop of NDT Experts CY - Prague, Czech Republic DA - 2005-10-10 KW - Masonry KW - Tomography KW - Ultrasonic KW - Radar KW - Non-destructive testing PY - 2005 SN - 80-2142996-8 SP - 299 EP - 313 PB - Univ. of Technology CY - Brno AN - OPUS4-12273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cotic, P. A1 - Jaglicic, Z. A1 - Niederleithinger, Ernst A1 - Effner, Ute A1 - Kruschwitz, Sabine A1 - Trela, Christiane A1 - Bosiljkov, V. T1 - Effect of moisture on the reliability of void detection in brickwork masonry using radar, ultrasonic and complex resistivity tomography N2 - The influence of moisture on the reliability of detection of larger voids in brickwork masonry was investigated using three non-destructive techniques: radar, ultrasonic and complex resistivity (CR). Radar and ultrasonic travel time tomography, as well as CR tomography, were performed over a specific cross section of a specimen containing a large void at a known position to determine the influence of different levels of moisture content in the brickwork on the wave velocities and the CR magnitude. We defined a numerical estimator to quantitatively determine the void detection efficiency from the images obtained when exposing the specimen to moisture. The results showed radar to be the most reliable technique for void detection in both dry and wet masonry, while CR performed much better in detecting larger air voids in wet masonry. KW - Radar KW - Ultrasonic and complex resistivity KW - Tomography KW - Masonry KW - Moisture KW - Void detection KW - Ultrasound PY - 2013 DO - https://doi.org/10.1617/s11527-012-0011-3 SN - 1359-5997 SN - 1871-6873 VL - 46 IS - 10 SP - 1723 EP - 1735 PB - Springer CY - Dordrecht AN - OPUS4-29991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -