Author: Hee Jeong ShinPublisher:
ISBN:
Category :
Languages : en
Pages : 174
Book Description
Probabilistic Bridge Deck Condition Analysis Using Ground Penetrating Radar (GPR).
Author: Hee Jeong ShinGround Penetrating Radar-based Deterioration Assessment of Bridge Decks
Author: Ahmad ShamiPublisher:
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.
Advanced Approaches for Bridge Deck Assessment Using Ground Penetrating Radar
Author: Aleksey Kamilevich KhamzinPublisher:
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.
LTBP News
Author: Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 16
Book Description
Assessing the condition of bridge deck surfaces using ground penetrating radar (GPR), using electromagnetic pulses to text, characterize, or detect subsurface anomalies.
Ground Penetrating Radar for Concrete Bridge Deck Evaluation
Author: Daniel E. DiazPublisher:
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.
Application of Ground Penetrating Radar (GPR) for Bridge Deck Condition Assessment: Using a 1.5 GHz Ground-coupled Antenna
Author: Amos WamweyaPublisher:
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
Condition Assessment of Concrete Bridge Decks Using Ground Penetrating Radar
Author: Kien DinhGround Penetrating Radar Bridge Deck Investigations Using Computational Modeling
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.
Condition Assessment of Reinforced Concrete Bridge Decks as Conductive Media Using GPR
Author: Adam J. SketchleyPublisher:
ISBN:
Category :
Languages : en
Pages : 220
Book Description
ABSTRACT Cont.'d : Finally, determined conductivities were compared to chloride contents measured from cores taken from each deck at the time of testing. Conductivity was shown to increase linearly with chloride content, confirming the ability of ground penetrating radar to detect chlorides. This relationship can be used to map chloride content across a bridge deck and estimate the time to corrosion, greatly increasing the efficiency of bridge deck inspection.
Bridge Deck Condition Assessment Using Destructive and Nondestructive Methods
Author: Brandon Tyler GoodwinPublisher:
ISBN:
Category : Bridges
Languages : en
Pages : 134
Book Description
"This study investigates two bridge decks in the state of Missouri using both nondestructive and destructive testing methods. The Missouri Department of Transportation (MoDOT) is responsible for the monitoring and maintenance of over 10,000 bridges. Currently monitoring of these bridges includes a comprehensive visual inspection. In this study, ground-coupled ground penetrating radar (GPR) is used to estimate deterioration, along with other traditional methods, including visual inspection, and core evaluation. Extracted core samples were carefully examined, and the volume of permeable pore space was determined for each core. After the initial investigation, the two bridges underwent rehabilitation using hydrodemolition as a method to remove loose or deteriorated concrete. Depths and locations of material removal were determined using light detection and ranging (lidar). Data sets were compared to determine the accuracy of GPR to predict deterioration for condition monitoring and rehabilitation planning of bridge decks. As shown by the lidar survey of the material removed during rehabilitation, the GPR top reinforcement reflection amplitude accurately predicted regions of deterioration within the bridge decks. In general, regions with lower reflection amplitudes, indicating more evidence of deterioration, corresponded to regions with greater depths of material removal during the rehabilitation. Also, the GPR top reinforcement reflection amplitude indicated deterioration in areas where visual deterioration was noticed from the top surface of the deck. The majority of cores with delaminations were extracted from sections where the GPR top reinforcement reflection amplitude indicated greater evidence of deterioration based on lower amplitude values."--Abstract, page iii.