Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (9)
- Beitrag zu einem Tagungsband (7)
- Beitrag zu einem Sammelband (4)
- Vortrag (1)
- Sonstiges (1)
- Posterpräsentation (1)
- Forschungsbericht (1)
Schlagworte
- Beton (4)
- Concrete (4)
- Monitoring (4)
- Ultraschall (4)
- Brücke (3)
- Condition assessment (3)
- Fundament (3)
- Impulse radar (3)
- LAUS (3)
- Non-Destructive Testing (3)
- Non-destructive testing (3)
- Ultrasound (3)
- Coda wave interferometry (2)
- Embedded sensors (2)
- Impact echo (2)
- Impact-echo (2)
- Stress (2)
- Transmission (2)
- Ultrasonic echo (2)
- Ultrasonics (2)
- Acoustic emission (1)
- Active thermography (1)
- Automated scanning (1)
- Automated scanning device (1)
- Automated scanning systems (1)
- Automation of measurement (1)
- Beton Ultraschall Monitoring (1)
- Bridge assessment (1)
- Bridges (1)
- Category IIIC (1)
- Civil engineering (1)
- Coda wave inteferometry (1)
- Codawelleninterferometrie (1)
- Combination of methods (1)
- Conference (1)
- Construction (1)
- Correlation (1)
- Cracks (1)
- Damages (1)
- Data fusion (1)
- Deep penetration (1)
- Embedded ultrasonic sensors (1)
- Enhanced Imaging (1)
- Environment and Energy (1)
- Feuchte (1)
- Foundations (1)
- Freeze-thaw (1)
- Frost-Tauwechsel (1)
- Impedanzspektroskopie (1)
- Impulse thermography (1)
- Integrity (1)
- LAUS (Large Apertur Ultrasonic System) (1)
- LIBS (1)
- Lastconcrete (1)
- Load (1)
- Masonry (1)
- Mauerwerk (1)
- Multi-Offset Array (1)
- NDT (1)
- NDT-toolbox (1)
- Neue Verfahren/Versuchstechnik (1)
- New Processes/Experimental Techniques (1)
- Non-destructive testing (NDT) (1)
- Non-destructive testing in civil engineering (1)
- Nuclear structures (1)
- Parallel seimics (1)
- Piles (1)
- Radar (1)
- Railway Bridges (1)
- Research needs (1)
- SHM (1)
- SIP (1)
- Salzgehalt (1)
- Scanning system (1)
- Sensor network (1)
- Slabs (1)
- Spektrale Induzierte Polarisation (1)
- State of the art (1)
- Structural Health Monitoring (1)
- Support vector machine (1)
- Thermography (1)
- Tomography (1)
- Transducers (1)
- Ultraschallsensoren, eingebettete (1)
- Ultrasonic-echo (1)
- Ultrasonicecho (1)
- Ultrasound concrete (1)
- Utility poles (1)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (1)
Ultrasonic echo and transmission techniques are used in civil engineering on a regular basis. New sensors and data processing techniques have lead to many new applications in the structural investigation as well as quality control. But concrete structures in the nuclear sector have special features and parameters, which pose problems for the methods and instrumentation currently available, e.g. extreme thickness, dense reinforcement, steel liners or special materials. Several innovative ultrasonic techniques have been developed to deal with these issues at least partly in lab experiments and pilot studies. Modern imaging techniques as multi-offset SAFT have been used e. g. to map delaminations. Thick concrete walls have successfully been inspected, partly through a steel liner. Embedded ultrasonic sensors have been designed which will be used in monitoring networks of large concrete structures above and below ground. In addition, sensitive mathematical methods as coda wave interferometry have been successfully evaluated to detect subtle changes in material properties. Examples of measurements and data evaluation are presented.
The LAUS: First Applications of a New System for Ultrasonic Imaging of Very Concrete Structures
(2019)
The LAUS (Large Aperture Ultrasonic System) has been developed to image very thick concrete structures, which are not accessible for commercial systems. The device and the corresponding software is the result of joint Research of BAM, an ultrasonic instrument manufacturer and University of Kassel, Germany. It consists of 12 separate Arrays of 32 point-contact shear wave transducers each, which can be deployed in flexible configurations. Each array is combined with battery and transmitter, receiver and wireless communication electronics.
Three case histories are presented. First the system was deployed on a 5-m thick heavily reinforced foundation slab.
The reflection of the slab’s bottom was imaged clearly. In addition, a multiple reflection was registered, thus giving hope that even thicker elements might be imaged by the instrument. Second, the LAUS was used to investigate a massive bridge girder where a heavy rainstorm during concreting had led to imperfections that were visible after removing the formwork was removed. The LAUS could image tendon ducts in 1.8m depth and the backwall closely behind them. Some limited areas showed blurred reflections and were checked by drill holes; these areas were affected by diffuse damage which could be repaired by injections. Third, a large retaining wall was checked for thickness.
Meanwhile, the LAUS has been used in underground waste deposits (nuclear and other) for quality assurance of sealing plugs. A confirmed penetration depth of about 7 m has been reached.
The European infrastructure asset has developed historically and is characterized by nation-specific construction processes. Inspection, condition assessment, and maintenance procedures differ from country to country. Because of historical and political circumstances, national infrastructure assets are maintained at different levels, too. Since the budget for maintaining the bridge infrastructure less and less meets the demands of a growing bridge stock, bridge inspection, maintenance, and life-cycle considerations gain higher importance. The need exists to develop effective diagnosis tools for early detection of construction faults, defects, and deterioration processes during inspection, to keep the bridge infrastructure at an acceptable level, from structural safety and economic viewpoints. An overview on the latest research projects and integrated bridge management systems in Europe is given. The potentials of nondestructive testing (NDT) are presented, with special focus on technical advances of NDT applications to reinforced concrete (RC) and posttensioned concrete bridges. Although NDT is not regularly integrated in these processes, the application brings valuable information on the current condition of the inner structure in called-in special inspections. NDT-automation and the application of imaging echo methods, combined with advanced data processing, produce a surprising level of information about the inner structure of massive RC slabs up to a depth of about 60 cm. Detected inhomogeneity and scatterers of acoustic or electromagnetic waves can be visualized in vertical or horizontal slices through the structure or animations. The fusion of different three-dimensional data sets of processed data improves the interpretability and accuracy of the results.
ZfPBau-Kompendium 2004
(2007)
Dieses Kompendium ist ein kurzgefasster Abriss, ein Leitfaden und auch ein Handbuch der für den Einsatz im Bauwesen geeigneten zerstörungsfreien Prüfverfahren. In strenger, stets gleicher Gliederung wird jede der mehr als 100 Untersuchungsmethoden in einem eigenen Geräteblatt beschrieben. Hinzu kommen Querverweise zu alternativen Prüfmethoden sowie zahlreiche Hinweise auf einschlägige Fachliteratur und zu bekannt gewordenen Geräteherstellern, Lieferanten und Dienstleistern.
Die Coda transmittierter Ultraschallsignale in Beton enthält Informationen zu Struktur und Zustand des Materials bzw. deren Änderung. Relevant sind u. a. Temperatur, Stress, Feuchtigkeit und verschiedene Schädigungsmechanismen. Die zahlreichen Einflussfaktoren sind nur schwer zu trennen und die Messeffekte oft zu Beginn sehr klein.Die CWI ermöglicht die Detektion kleinster Geschwindigkeitsveränderungen durch den Vergleich, der in kleinen Schritten gestauchten oder gestreckten Signalen mit eine Referenzmessung. Andere Indikatoren für Änderungen im Material sind:
• Kreuzkorrelation
• Laufzeit direkte Welle
• Energie/Amplitude
• Änderungen im Frequenzspektrum
Die beschriebene Technik wird von uns bisher primär in klein- und großskaligen Laborversuchen genutzt. Die Forschung konzentriert sich auf die Untersuchung und Trennung verschiedener Einflusseffekte. Aber auch erste reale Bauwerke wurden schon instrumentiert, z. B. Brücken und eine Tunneldecke.
LAUS - Erste praktische Erfahrungen mit einem neuartigen Ultraschallsystem großer Eindringtiefe
(2018)
Konventionelle Systeme zur Ultraschall-Echo-Prüfung von Betonbauteilen sind in ihrer Eindringtiefe auf etwa einem Meter begrenzt. Zur Prüfung stärkerer Objekte war die Entwicklung eines neuartigen Prüfsystems notwendig. Das LAUS-System (Large Aperture UltraSound) besteht aus 12 einzelnen Arrays, die mit jeweils 32 Einzelprüfköpfen (Scherwellen, 25 – 50 kHz) als Sender oder Empfänger betrieben werden können. Sie werden unabhängig auf Betonoberflächen mit Unterdruck befestigt und kommunizieren drahtlos untereinander und mit der Zentraleinheit. Alle möglichen Kombinationen ergeben 132 Einzelmessungen, die zur Rekonstruktion des durchschallten Volumens genutzt werden. Mehrere dieser Datensätze lassen sich zu einer 3D-Auswertung kombinieren. Das System wurde an mehreren Testobjekten und Bauwerken erfolgreich erprobt. So konnte die fünf Meter dicke, sehr stark bewehrte Fundamentplatte des Fallturms auf dem BAM-Testgelände bei Horstwalde durchschallt werden. Ein zweites Beispiel ist die erfolgreiche Detektion von Spannkanälen in 1,8 m Tiefe in einem massiven Brückenbauwerk.