Ground Penetrating Radar Bridge Deck Investigations Using Computational Modeling PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Ground Penetrating Radar Bridge Deck Investigations Using Computational Modeling PDF full book. Access full book title Ground Penetrating Radar Bridge Deck Investigations Using Computational Modeling by . Download full books in PDF and EPUB format.
Author: Publisher: ISBN: Category : Bridges Languages : en Pages : 230
Book Description
Infrastructure in the United States is failing. According to a 2005 study by the American Society of Civil Engineers over a quarter of the bridges are structurally deficient or functionally obsolete. Condition assessment without the assistance of subsurface sensing techniques leads to poor detection and quantification of damage because much of the damage and precursors to damage is hidden beneath the surface. Ground Penetrating Radar (GPR) a popular choice for bridge deck assessment, depends on a subjective process, which is the trained eye of a technician. The ability to simulate a GPR investigation provides insight into the response from bridge deck elements, as well as the interaction among the elements and changes due to the presence of an anomaly and supports defect detection. A subsurface modeling tool is developed with physical modeling components available for general applications but extended to meet specific requirements for geometric modeling of civil infrastructure. The simulation component implements the 2-dimensional Finite Difference Time Domain (FDTD) method for electromagnetic modeling. Comparisons between 2D and 3D simulations show that, for bridge deck analysis, 2D modeling is adequate for condition assessment. A model-based assessment augments the conventional approach to analysis by using iterative computational models to reconstruct the bridge deck in a healthy condition. To identify areas of suspect condition, the response from the computed healthy deck can be compared to the response collected in the field. The effect of the presence of rebars on the scattering from an anomaly can be significant, and is not easily removed from GPR data. In the computational model, the strong scattering rebars are replaced with an excitation source that results in wave propagation equivalent to the scattering from the rebar. This technique makes the GPR bridge deck problem better suited to the traditional inversion algorithms that are often complicated by strong scatterers. Through experimentation, the GPR antenna can be characterized to determine a virtual sensor for the 2D FDTD model. The resulting sensor allows for a significantly smaller geometry, which saves time and computational resources while reducing differences in propagation associated with using a 2-dimensional instead of 3-dimensional model.
Author: Publisher: ISBN: Category : Bridges Languages : en Pages : 230
Book Description
Infrastructure in the United States is failing. According to a 2005 study by the American Society of Civil Engineers over a quarter of the bridges are structurally deficient or functionally obsolete. Condition assessment without the assistance of subsurface sensing techniques leads to poor detection and quantification of damage because much of the damage and precursors to damage is hidden beneath the surface. Ground Penetrating Radar (GPR) a popular choice for bridge deck assessment, depends on a subjective process, which is the trained eye of a technician. The ability to simulate a GPR investigation provides insight into the response from bridge deck elements, as well as the interaction among the elements and changes due to the presence of an anomaly and supports defect detection. A subsurface modeling tool is developed with physical modeling components available for general applications but extended to meet specific requirements for geometric modeling of civil infrastructure. The simulation component implements the 2-dimensional Finite Difference Time Domain (FDTD) method for electromagnetic modeling. Comparisons between 2D and 3D simulations show that, for bridge deck analysis, 2D modeling is adequate for condition assessment. A model-based assessment augments the conventional approach to analysis by using iterative computational models to reconstruct the bridge deck in a healthy condition. To identify areas of suspect condition, the response from the computed healthy deck can be compared to the response collected in the field. The effect of the presence of rebars on the scattering from an anomaly can be significant, and is not easily removed from GPR data. In the computational model, the strong scattering rebars are replaced with an excitation source that results in wave propagation equivalent to the scattering from the rebar. This technique makes the GPR bridge deck problem better suited to the traditional inversion algorithms that are often complicated by strong scatterers. Through experimentation, the GPR antenna can be characterized to determine a virtual sensor for the 2D FDTD model. The resulting sensor allows for a significantly smaller geometry, which saves time and computational resources while reducing differences in propagation associated with using a 2-dimensional instead of 3-dimensional model.
Author: Amos Wamweya Publisher: ISBN: Category : Bridges Languages : en Pages : 0
Book Description
"This study is a GPR-based assessment of three bridge decks, two with a hot bituminous wearing surface and one with a bare concrete slab. The primary objectives of this study were: 1) to assess the integrity of the three bridge decks using a 1.5 GHz ground-coupled GPR antenna, and 2) to evaluate the utility of the 1.5 GHz ground-coupled antenna for bridge deck investigations. Core control (chloride ion concentration data and core integrity data) and visual inspection were used as interpretive constraint. The acquired GPR data were interpreted, and two plan view maps were generated. One depicts the magnitude of the reflections from the uppermost mat of rebar, and the second shows the arrival time of these reflections. Analysis of the GPR data and core control indicates that the magnitude of the reflected GPR signal from the uppermost mat of rebar is a direct function of concrete integrity. Higher magnitude reflections indicate higher quality concrete. To a lesser extent, the arrival time of the reflected energy is also indicative of concrete quality. Faster arrival times generally indicate higher quality concrete. Exceptions to this rule occur where the depth to the top layer of rebar varies. In this study, relative reflection amplitudes of less than 3000 on the bare concrete bridge and less than 5000 on the bituminous surface bridges indicate severe deterioration. Core control data was interpreted based on chloride ion corrosion threshold. Corrosion of rebar occurs once chloride ions content adjacent to the rebar reaches a threshold of approximately 0.033% to 0.04% by weight of concrete (or 330 ppm to 400 ppm). The GPR data correlates well with the core control, indicating that the 1.5 GHz antenna is an effective tool for assessing the condition of bridge decks"--Abstract, leaf iii
Author: Publisher: ISBN: Category : Aeronautics Languages : en Pages : 880
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Lesley Sneed Publisher: ISBN: Category : Concrete bridges Languages : en Pages : 49
Book Description
This study demonstrated the utility of the air launched ground penetrating radar (GPR) tool in terms of evaluating the condition of MoDOT bridge decks. The objective was to confirm that the air-launched GPR tool can be implemented as a part of a long-term program that enables faster, better, and more cost-effective assessments of MoDOT bridge decks. Ten bridge decks were investigated using an air-launched GPR system. Four of the bridge decks investigated were previously investigated using a ground-coupled GPR system, and results from those four bridge decks served as ground truth for the air-launched GPR interpretations. Findings show reasonably good spatial correlation between the ground-coupled GPR and air-launched GPR datasets in terms of deteriorated regions and overall percentages of deteriorated regions in terms of bridge deck surface area. Apparent discrepancies between the air launched and ground-coupled GPR interpretations can be attributed to several factors, including interpolation between adjacent GPR traverses, differences in signal attenuation due to different antenna frequencies, and differences in signal resolution due to different distance from the antenna to the embedded reinforcing steel. Recommendations for optimum acquisition, processing, and interpretation parameters for air-launched GPR reconnaissance-style assessment were provided as part of this study.
Author: Aleksey Kamilevich Khamzin Publisher: ISBN: Category : Bridges Languages : en Pages : 194
Book Description
"Ground penetrating radar (GPR) data were acquired across four bridge decks with the objective of developing an advanced workflow for GPR operation that would allow the bridge owners to estimate repair quantities for certain bridge decks, based on GPR data. The primary contributions from this research are as follows: 1. It was demonstrated that the conditions of bridge decks can be cost-effectively and efficiently assessed using the GPR tool. 2. The GPR tool's ability to provide rapid and reliable results in comparison with conventional bridge deck condition assessment techniques was established. 3. The qualitative and quantitative relationships between the GPR reflection amplitude and depth of concrete degradation were analyzed to develop an effective technique to estimate the amount of deteriorated concrete present in a particular bridge deck; this technique could enable bridge owners to use the GPR tool (only) to estimate the thickness of concrete that would be removed by processes such as hydro demolition. 4. The air-launched and ground-coupled GPR systems were compared in terms of accuracy of data acquisition and reliability of results. It was determined that air-launched GPR is a reliable tool for the fast and cost-effective assessment of bridge decks. This work is new and important because it extends the traditional use of the GPR technique and presents the advanced approach for data interpretation and concrete material removal estimation, especially in areas where deterioration was not visually exposed"--Abstract, page iii.
Author: Wooyoung Kim Publisher: ISBN: Category : Ground penetrating radar Languages : en Pages : 128
Book Description
"The present study is comprised of two separate GPR case studies on a bridge deck and a concrete pavement respectively. These typical concrete structures were investigated using GPR with several objectives: 1) to find the reason of discrepancies between GPR results and the results of the other tests through bridge deck inspection, 2) to investigate the bridge deck under various weather conditions, 3) to determine the relative spatial locations of the imbedded dowel bars in the new concrete pavement, and finally 4) to evaluate the present capabilities of GPR technology including survey scheme and analysis through these two case studies."--Abstract, p. iii.
Author: 
Author: 
Author: Hee Jeong Shin
Author: Rauno Heikkilä
Author: Amos Wamweya
Author: Christopher Franklin Wright
Author: 
Author: Lesley Sneed
Author: John P. Warhus
Author: Aleksey Kamilevich Khamzin
Author: Wooyoung Kim