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Author: Ahmad Shami Publisher: ISBN: Category : Languages : en Pages : 138
Book Description
The ASCE report card 2013 rated bridges at a grade of C+, implying their condition is moderate and require immediate attention. Moreover, the Federal Highway Administration reported that it is required to invest more than $20.5 billion each year to eliminate the bridge deficient backlog by 2028. In Canada 2012, more than 50% of bridges fall under fair, poor, and very poor categories, where more than $90 billion are required to replace these bridges. Therefore, government agencies should have an accurate way to inspect and assess the corrosiveness of the bridges under their management. Numerical Amplitude method is one of the most common used methods to interpret Ground Penetrating Radar (GPR) outputs, yet it does not have a fixed and informative numerical scale that is capable of accurately interpreting the condition of bridge decks. To overcome such problem, the present research aims at developing a numerical GPR-based scale with three thresholds and build deterioration models to assess the corrosiveness of bridge decks. Data, for more than 60 different bridge decks, were collected from previous research works and from surveys of bridge decks using a ground-coupled antenna with the frequency of 1.5 GHz. The amplitude values of top reinforcing rebars of each bridge deck were classified into four categories using k-means clustering technique. Statistical analysis was performed on the collected data to check the best-fit probability distribution and to choose the most appropriate parameters that affect thresholds of different categories of corrosion and deterioration. Monte-Carlo simulation technique was used to validate the value of these thresholds. Moreover, a sensitivity analysis was performed to realize the effect of changing the thresholds on the areas of corrosion. The final result of this research is a four-category GPR scale with numerical thresholds that can assess the corrosiveness of bridge decks. The developed scale has been validated using a case study on a newly constructed bridge deck and also by comparing maps created using the developed scale and other methods. The comparison shows sound and promising results that advance the state of the art of GPR output interpretation and analysis. In addition, deterioration models and curves have been developed using Weibull Distribution based on GPR outputs and corrosion areas. The developed new GPR scale and deterioration models will help the decision makers to assess accurately and objectively the corrosiveness of bridge decks. Hence, they will be able to take the right intervention decision for managing these decks.
Author: Ahmad Shami Publisher: ISBN: Category : Languages : en Pages : 138
Book Description
The ASCE report card 2013 rated bridges at a grade of C+, implying their condition is moderate and require immediate attention. Moreover, the Federal Highway Administration reported that it is required to invest more than $20.5 billion each year to eliminate the bridge deficient backlog by 2028. In Canada 2012, more than 50% of bridges fall under fair, poor, and very poor categories, where more than $90 billion are required to replace these bridges. Therefore, government agencies should have an accurate way to inspect and assess the corrosiveness of the bridges under their management. Numerical Amplitude method is one of the most common used methods to interpret Ground Penetrating Radar (GPR) outputs, yet it does not have a fixed and informative numerical scale that is capable of accurately interpreting the condition of bridge decks. To overcome such problem, the present research aims at developing a numerical GPR-based scale with three thresholds and build deterioration models to assess the corrosiveness of bridge decks. Data, for more than 60 different bridge decks, were collected from previous research works and from surveys of bridge decks using a ground-coupled antenna with the frequency of 1.5 GHz. The amplitude values of top reinforcing rebars of each bridge deck were classified into four categories using k-means clustering technique. Statistical analysis was performed on the collected data to check the best-fit probability distribution and to choose the most appropriate parameters that affect thresholds of different categories of corrosion and deterioration. Monte-Carlo simulation technique was used to validate the value of these thresholds. Moreover, a sensitivity analysis was performed to realize the effect of changing the thresholds on the areas of corrosion. The final result of this research is a four-category GPR scale with numerical thresholds that can assess the corrosiveness of bridge decks. The developed scale has been validated using a case study on a newly constructed bridge deck and also by comparing maps created using the developed scale and other methods. The comparison shows sound and promising results that advance the state of the art of GPR output interpretation and analysis. In addition, deterioration models and curves have been developed using Weibull Distribution based on GPR outputs and corrosion areas. The developed new GPR scale and deterioration models will help the decision makers to assess accurately and objectively the corrosiveness of bridge decks. Hence, they will be able to take the right intervention decision for managing these decks.
Author: Publisher: Transportation Research Board ISBN: 0309129338 Category : Technology & Engineering Languages : en Pages : 96
Book Description
" TRB's second Strategic Highway Research Program (SHRP 2) Report S2-R06A-RR-1: Nondestructive Testing to Identify Concrete Bridge Deck Deterioration identifies nondestructive testing technologies for detecting and characterizing common forms of deterioration in concrete bridge decks.The report also documents the validation of promising technologies, and grades and ranks the technologies based on results of the validations.The main product of this project will be an electronic repository for practitioners, known as the NDToolbox, which will provide information regarding recommended technologies for the detection of a particular deterioration. " -- publisher's description.
Author: Parneet Kaur Publisher: ISBN: Category : Concrete bridges Languages : en Pages : 79
Book Description
Reinforcement concrete (RC) bridge decks are surveyed regularly to ensure that they are safe to use and to determine if they require rehabilitation or replacement. The bridge surveys include evaluating subsurface bridge condition. RC bridges have steel reinforcement bars, also called rebars, embedded in their surface, which are prone to corrosion due to factors like moisture, carbonation, use of deicing salts and aging. By the time the effect of corroded rebars is visible on deck surface in form of cracks, the damage is tremendous. If left unchecked, corroded rebars can deteriorate at a faster and significantly affect bridge integrity. So, it is very important to timely identify and repair deteriorated rebars. Ground Penetrating Radar (GPR) is a widely used non-destructive technology (NDT) for detecting subsurface anomalies in variety of structures including RC bridges. The raw GPR data is represented as images that can be processed for obtaining a deterioration map of a bridge, which indicates the level of corrosion in rebars for the entire bridge. The existing methods to generate the deterioration map using GPR data are semi-automated, time consuming and depends on expertise of the engineer analyzing the data. In this thesis, we work towards automating the process of obtaining deterioration map of RC bridge decks based on measuring signal attenuation at the upper rebar mat using GPR. Intensity and gradient-based feature vectors were explored to construct a classifier, which can detect the regions of interest (ROI) corresponding to each rebar in images. Each classifier was tested on datasets constructed from two different bridges. Further, the exact location of rebar was found in each ROI. Once all the rebars were detected throughout the bridge, depth-correction of the measured attenuation is applied so that the component of that measured attenuation caused solely by variation in rebar depth does not skew the results. Finally, a deterioration map was generated which indicates the level of corrosion in the bridge. The proposed algorithm was tested on two RC bridges and the deteriorated regions obtained are compared with the results obtained using existing tools.
Author: Daniel E. Diaz Publisher: ISBN: Category : Languages : en Pages : 308
Book Description
As the nation's infrastructure continues to age, there is a need to effectively and economically monitor and inspect bridges. With the introduction of non-destructive testing technologies such as Ground Penetrating Radar (GPR) for condition assessment of bridge decks, states will be better equipped to inspect, assess, and prioritize transportation funding to maintain, preserve, and improve infrastructure. The objective of the research is to improve the condition assessment of bridge decks through the use of GPR which can increase the speed, effectiveness, and accuracy of inspections. The non-destructive evaluation technique provides information that can be used to identify the potential amount of internal deterioration of a concrete bridge deck that cannot be identified with a visual inspection. As in many other states, New Mexico currently uses the chain drag method in which the inspection of the deck condition is solely based on inspector's subjective interpretation of the sound produced by dragging a chain over the bridge deck. The use of GPR has the potential to greatly improve the quality of the inspections by collecting more reliable and less subjective information on the condition of bridge decks. Through the collection and analysis of data acquired from the GPR on a set of reinforced concrete decks, this research seeks to provide a better understanding of GPR technology, data acquisition, and training needs for adoption of GPR in bridge deck inspections in the state of New Mexico. With a better understanding of the technology, GPR can become and indispensable tool for more informed decisions for the allocation of funds for maintenance and improved asset management. This research improves implementation and provides effective economic methods to employ this technology to improve the inspection and maintenance of bridge infrastructure.
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: 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: Ahmad Shami
Author: Ahmad Shami
Author: Kien Dinh
Author: 
Author: Parneet Kaur
Author: Jeffrey Scott Klein
Author: Daniel E. Diaz
Author: Kenneth R. Maser
Author: Amos Wamweya
Author: Kenneth R. Maser
Author: Aleksey Kamilevich Khamzin