Development of Ultrasonic Techniques for Detection of Internal Defects in Highway Concrete Structures PDF Download

Author: Aliakbar Afshari
Publisher:
ISBN:
Category : Concrete construction
Languages : en
Pages : 566

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Author: Sandor Popovics
Publisher:
ISBN:
Category : Algorithms
Languages : en
Pages : 25

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Book Description
This Innovations Deserving Exploratory Analysis (IDEA) project developed and demonstrated the feasibility of a nondestructive ultrasonic technique based on modified split spectrum processing (SSP) and its rationalization using a statistical spectral histogram technique (SHT) for field evaluation of highway concrete structures. Following the selection, evaluation and optimization of the initial instrumentation, a new algorithm was developed that allowed automatic selection of optimum or near optimum parameters for SSP and performing the SSP using the selected parameters. A software system was developed that allowed spectral histogram analysis for the direct determination of the frequency region without trial and error. The software was successfully tested for several cases including the determination of thickness and internal defects of a concrete slab. The combination of SSP with SHT reduced the noise thereby significantly improving the interpretation of the received high frequency ultrasound. Also, the computerized form made the application simple and rapid. The improved process can further be extended to produce two-dimensional images for improved diagnosis of concrete structures.

Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 872

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Author: Joshua White
Publisher:
ISBN:
Category :
Languages : en
Pages :

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This thesis evaluates a particular ultrasonic nondestructive testing (NDT) system in order to determine its capabilities and limitations in locating defects in concrete structures; specifically tunnel linings, bridge decks, and pavements. The device, a phased-array ultrasonic tomography (UST) system that utilizes shear waves, is a significant advancement in NDT systems. Consequently, there is a need in structural engineering to verify new technologies by assessing their flaw-detecting capabilities in a variety of structural applications. The UST technique does not currently have a testing methodology that is field-ready. In order to develop a methodology, the system was evaluated based on its ability to detect simulated defects, then taken to the field to evaluate natural structural defects on public tunnels, pavements, and airport runways. Types of concrete defects the system is used to detect and localize include air- and water-filled voids, vertical cracks, horizontal delaminations, and abnormalities such as clay lumps. The device is also used to determine reinforcement depth and spacing as well as concrete thickness measurements. This research concludes that the UST system is exceptional at locating horizontal delaminations ranging from 0.05-2.0 mm (0.002-0.079 in.), and is able to differentiate between fully debonded and partially-bonded areas. Vertical cracks could only be detected once they begin to form parallel to the testing surface; however, omission of surface details was found to be a strong indicator of crack presence. Backwall surfaces up to a depth of 762 mm (30 in.) were successfully and accurately determined. Air- and water-filled voids as well as reinforcement details such as layout and depth were also successfully determined and located. With the exception of some medium-sized clay lumps (with a diameter of approximately 102 mm, or 4 in.) surrounding reinforcement, all clay lumps tested were also highly successful.

Author:
Publisher:
ISBN:
Category : Highway research
Languages : en
Pages : 610

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Author: J.S. Jensen
Publisher: Routledge
ISBN: 1351426982
Category : Technology & Engineering
Languages : en
Pages : 234

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Major Infrastructure links across water represent large investments. The structures and systems must be optimised to keep costs in control. Optimisation needs and the tendancy to more slender and light structures imply that engineering disciplines like Bridge Aerodynamics and Ship Collision Analysis have an increasing impact on the overall design of links. Also the attention to life cycle costs implies Operation and Maintenance must to investigated and planned in parallel to the design and construction of the links. The 1998 International Symposium aims at presenting state-of-the-art and future development within the three mentioned engineering disciplines. Exploring the many facets of major infrastructure projects, this symposium concentrated on developments within organisational, strategic and policy areas and both traffic and o & m management. Contributors to the papers include operators, consultants and international, experienced owners.

Author: Mary Sansalone
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 344

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Author: V. M. Malhotra
Publisher: CRC Press
ISBN: 0803120990
Category : Technology & Engineering
Languages : en
Pages : 389

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Book Description
Civil engineers will value this resource that examines the tools and techniques used to estimate the in-place strength on concrete, permeation properties that relate to potential durability, and the methods used to assess the internal condition of concrete and the corrosion activity of steel reinforcement.

Author: David G. Manning
Publisher: Transportation Research Board National Research
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 64

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Book Description
The need to detect defects and deterioration in highway structures ranges from reasons of safety to the prediction of load capacity to the information base for a bridge manangement system. The emphasis here is on test procedures that can be used in the field and guidance is given in interpreting the significance of measured values. Although it is usually possible to detect deterioration in a component of a structure, it is often difficult to assess the effect of the deterioration on the load-carrying capacity of the structure. Often, full scale testing is justified to measure the overall condition of a structure. A survey of current practices revealed that concrete structures are being tested more extensively than steel or timber structures.

Author: Ji-yong Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 312

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Characterization of defect is one of the important objectives of nondestructive evaluation (NDE) for condition assessment of structures. Among many other NDE techniques, ultrasonic methods play a prominent role in the both quantitative and qualitative assessment of discontinuities in reinforced cementitious materials. Due to the heterogeneous nature of concrete, ultrasonic waves are highly scattered and attenuated, leading to the difficulty of concrete inspection using conventional ultrasonic techniques, including those that work well on relatively homogeneous materials such as metals. This thesis presents an advanced method for sizing and imaging of defects in reinforced cementitious materials. A two-dimensional, three-phase composite model of concrete is proposed to study the propagation and interaction behaviors of ultrasonic waves in concrete structures, and to gain a knowledge about wave diffraction with multiple cylindrical obstacles. The response of the modeled concrete structure to an incident ultrasonic pulse input signal (pulsed ultrasonic P-wave) is analytically investigated and simulated. A characteristic profile of the defect sizing as a function of focal depth is formulated via the synthetic focusing technique. A defect sizing parameter, called characteristic width, is obtained empirically to represent the defect sizing information for the concrete. Conventional 2-D ultrasonic B-scan imaging, for example, by migration, may introduce artifacts. In this thesis, the fundamental theory for synthetic aperture beam-forming through synthetic steering and focusing of array transducers is investigated. It is possible to achieve high spatial and temporal resolution ultrasonic image free of artifacts. A time-frequency signal processing and image reconstruction algorithm are also studied. The proposed defect sizing and imaging methodology is tested with numerically simulated ultrasonic waveform signals based on the mechanical properties of a custom-made concrete specimen. Experimental works confirm the feasibility of defect sizing and imaging of the method. With the knowledge about the concrete structures being tested this method may provide a useful tool for ultrasonic NDE application to reinforced cementitious materials.