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DEVELOPMENT OF A SIMPLIFIED FINITE ELEMENT APPROACH FOR FRP BRIDGE DECKS.
Title
DEVELOPMENT OF A SIMPLIFIED FINITE ELEMENT APPROACH FOR FRP BRIDGE DECKS.
Creator
Vyas, Jignesh, Zhao, Lei, University of Central Florida
Abstract / Description
Moveable bridges in Florida typically use open steel grid decks due to the weight limitations. However, these decks present rideability, environmental, and maintenance problems, for they are typically less skid resistant than a solid riding surface, create loud noises, and allow debris to fall through the grids. Replacing open steel grid decks that are commonly used in moveable bridges with a low-profile FRP deck can improve rider safety and reduce maintenance costs, while satisfying the...
Show moreMoveable bridges in Florida typically use open steel grid decks due to the weight limitations. However, these decks present rideability, environmental, and maintenance problems, for they are typically less skid resistant than a solid riding surface, create loud noises, and allow debris to fall through the grids. Replacing open steel grid decks that are commonly used in moveable bridges with a low-profile FRP deck can improve rider safety and reduce maintenance costs, while satisfying the strict weight requirement for such bridges. The performance of the new deck system, which includes fatigue and failure tests were performed on full-size panels in a two-span configuration. The deck has successfully passed the preliminary strength and fatigue tests per AASHTO requirements. It has also demonstrated that it can be quickly installed and that its top plate bonds well with the wear surface. The thesis also describes the analytical investigation of a simplified finite element approach to simulate the load-deformation behavior of the deck system for both configurations. The finite element model may be used as a future design tool for similar deck systems. Loadings that were consistent with the actual experimental loadings were applied on the decks and the stresses, strains, and the displacements were monitored and studied. The results from the finite element model showed good correlation with the deflection and strain values measured during the experiments. A significant portion of the deck deflection under the prescribed loads is induced by vertical shear. This thesis presents the results from the experiments, descriptions of the finite element model and the comparison of the experimental results with the results from the analysis of the model.
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Date Issued
2006
Identifier
CFE0001510, ucf:47151
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001510
An Analytical Investigation of Prestressed Beam Bridge Performance Before and After Widening
Title
An Analytical Investigation of Prestressed Beam Bridge Performance Before and After Widening.
Creator
ORiordan Adjah, Chris, Zhou, Lei, Chopra, Manoj, Catbas, Necati, University of Central Florida
Abstract / Description
As traffic and congestion increase, so does the likelihood of collisions. The solution to this problem is usually through a rehabilitation process with two primary options: (1) widening/expansion of existing roadway and bridges and (2) complete replacement (new construction) of roadway and bridges. The first option is the most feasible and cost-effective. While roadway widening/expansion pose minimal issues, the same cannot be said of bridge widening. An existing bridge presents a multitude...
Show moreAs traffic and congestion increase, so does the likelihood of collisions. The solution to this problem is usually through a rehabilitation process with two primary options: (1) widening/expansion of existing roadway and bridges and (2) complete replacement (new construction) of roadway and bridges. The first option is the most feasible and cost-effective. While roadway widening/expansion pose minimal issues, the same cannot be said of bridge widening. An existing bridge presents a multitude of challenges during the planning and design phases, during construction, and throughout the structure's service life. Special attention is required in both the design and detailing of the widening in order to minimize construction and maintenance problems. The primary objective of this dissertation is to present a better understanding of structural behavior and capacity by studying an existing widened structure: a bridge that has been in service for over 40 years (constructed in 1972 and widened in 2002). The load demand on this bridge has doubled over the years. Consequently, the widened structural system is composed of four-span continuous prestressed concrete bridge segments.To better understand the widened 2002 bridge used in this study, an initial comparative analysis was performed, comparing the original 1972 bridge and the 2002 widened bridge. This comparative analysis included a determination of bridge capacity, distribution factors, and load-rating factors using current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Specifications design codes. However, the original codes used for the two bridges should also be noted, as follows: (1) the AASHTO Load Factor Design (LFD) Code was used for the original bridge; and (2) a combination of the AASHTO LFD and AASHTO LRFD Specifications were used for the existing widened bridge. Linear three-dimensional finite element models were developed for both bridges to obtain the maximum moment and shear values with varying HL-93 load cases for these analyses.To develop models that describe the possible existing condition of the 2002 widened bridge, a nonlinear model of one of the critical members in the structure was developed by changing the most critical parameters. The critical parameters are categorized as material properties and prestress losses. Sensitivity studies were conducted using parametric models for simulations with moving loads for the different load cases using the HL-93 truck. The load-rating and reliability indexes were computed for all the cases under different loading conditions. The parameters that have the most influence on load rating and reliability are also presented in the analyses. The information generated from these analyses can be used for better(-)focused visual inspection and widened bridge load rating criteria, and can also be used for developing a long(-)term widening structural monitoring plan. Additionally, this study will be used as a benchmark for future studies, and to establish a procedure and methodology for future bridge widening projects.
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Date Issued
2017
Identifier
CFE0006773, ucf:51866
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006773
Resilience of Bridges Following Aftershocks
Title
Resilience of Bridges Following Aftershocks.
Creator
Espinosa, Diego, Mackie, Kevin, Chopra, Manoj, Tatari, Mehmet, University of Central Florida
Abstract / Description
The ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on...
Show moreThe ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on providing a way of assessing the reduction in capacity for main-shocks as compared to aftershocks and the effects and importance of both in a bridge. The reduction in capacity was defined using three different ratios: ultimate force, stiffness, and strain energy ratio. The ratios were computed relative to an undamaged state following both the main-shock scenario and the main-shock combined with aftershock scenario. The force, stiffness, and strain energy quantities were obtained from lateral pushover analyses along the two lateral bridge axes. Probabilistic demand models describing the loss in capacity were formulated by pairing intensity measures, based on real ground motions obtained from previous earthquakes, for the main-shock and aftershock with the capacity ratios, obtained from nonlinear dynamic time history analysis. Additionally, the reduction in capacity was conditioned on residual displacement and intensity measure in an attempt to discover the reduction in capacity ratio due to the contribution of residual displacement and therefore separate contributions from geometrical and material nonlinearities. This thesis demonstrates that the usage of strain energy ratio provides a definition of capacity that ultimately provides the best correlation between capacity and intensity measure.
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Date Issued
2012
Identifier
CFE0004311, ucf:49494
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004311
RESPONSE SENSITIVITY OF HIGHWAY BRIDGES TO RANDOM MULTI-COMPONENT EARTHQUAKE EXCITATION
Title
RESPONSE SENSITIVITY OF HIGHWAY BRIDGES TO RANDOM MULTI-COMPONENT EARTHQUAKE EXCITATION.
Creator
Cronin, Kyle, Mackie, Kevin, University of Central Florida
Abstract / Description
Highway bridges provide a critical lifeline during extreme seismic events and must maintain serviceability under a large range of earthquake intensities. Consequently, the advent of more computational power has allowed more advanced analysis approaches for predicting performance and vulnerability of highway bridges under these seismic loads. In traditional two-dimensional finite element analyses, it has been demonstrated that the incidence angle of the ground motion can play a significant...
Show moreHighway bridges provide a critical lifeline during extreme seismic events and must maintain serviceability under a large range of earthquake intensities. Consequently, the advent of more computational power has allowed more advanced analysis approaches for predicting performance and vulnerability of highway bridges under these seismic loads. In traditional two-dimensional finite element analyses, it has been demonstrated that the incidence angle of the ground motion can play a significant role in structural response. As three-dimensional nonlinear time history analyses are used more frequently in practice, ground motions are still usually applied along a single bridge axis. It is unknown how three orthogonal components of ground motion excitation should be applied to the structure to best represent the true response. In this study, the fundamental behavior of three-dimensional ground motion was studied using single-degree-of-freedom elastic spectra. Mean spectra computed from various orientation techniques were found indistinguishable when the orthogonal components were combined. The effect of incidence angle on the nonlinear structural response of highway bridges was then investigated through extensive statistical simulation. Three different bridge models were employed for this study implementing a suite of 180 multi-component ground motion records of various magnitude-distance-soil bins. Probabilistic seismic demand models for various response parameters are presented comparing the effects of random incidence angle to that of recorded directions. Although there are instances where the angle of incidence can significantly amplify response, results indicated that incidence angle had negligible effect on average ensemble response. This is consistent with results from the spectral analysis, although existing literature has emphasized incidence angle as a significant parameter of multi-component analysis.
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Date Issued
2009
Identifier
CFE0002933, ucf:47973
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002933
ULTRA-HIGH PERFORMANCE FIBER REINFORCED CONCRETE IN BRIDGE DECKAPPLICATIONS
Title
ULTRA-HIGH PERFORMANCE FIBER REINFORCED CONCRETE IN BRIDGE DECKAPPLICATIONS.
Creator
Xia, Jun, Mackie, Kevin, University of Central Florida
Abstract / Description
The research presented in this dissertation focuses on the material characterization of ultrahigh performance fiber reinforced concrete (UHP-FRC) at both the microscopic and macroscopic scales. The macroscopic mechanical properties of this material are highly related to the orientation of the steel fibers distributed within the matrix. However, the fiber orientation distribution has been confirmed to be anisotropic based on the flow-casting process. The orientation factor and probability...
Show moreThe research presented in this dissertation focuses on the material characterization of ultrahigh performance fiber reinforced concrete (UHP-FRC) at both the microscopic and macroscopic scales. The macroscopic mechanical properties of this material are highly related to the orientation of the steel fibers distributed within the matrix. However, the fiber orientation distribution has been confirmed to be anisotropic based on the flow-casting process. The orientation factor and probability density function (PDF) of the crossing fiber (fibers crossing a cutting plane) orientation was obtained based on theoretical derivations and numerical simulations with respect to different levels of anisotropy and cut planes oriented arbitrarily in space. The level of anisotropy can be calibrated based on image analysis on cut sections from hardened UHP-FRC prisms. Simplified equations provide a framework to predict the mechanical properties based on a single fiber-matrix interaction rule selected from existing theoretical models. Along with the investigation of the impacts from different curing methods and available post-cracking models, a versatile parameterized uniaxial stress-strain constitutive model was developed and calibrated. The constitutive model was implemented in a finite element analysis software program, and the program was utilized in the preliminary design of moveable bridge deck panels made of passively reinforced UHP-FRC. This deck system was among the several alternatives to replace the problematic steel grid decks currently in use. Based on experimental investigations of the deck panels, failure occurred largely in shear rather than flexure during bending tests. However, this shear failure is not abrupt and usually involves large deformation, large sectional rotation, and wide shear cracks before loss of load-carrying capacity. This particular shear failure mode observed was further investigated numerically and experimentally. Three-dimensional FEM models with the ability to reflect the interaction between rebar and concrete were created in a commercial FEM software to investigate the load transfer mechanism before and after bond failure. Small-scale passively reinforced prisms were tested to verify the conclusions drawn from simulation results. In an effort to improve the original design, several shear-strengthened deck panels were tested and evaluated for effectiveness. Finally, methods and equations to predict the ultimate shear capacity were calibrated. A two-dimensional frame element based complete moveable bridge finite element model was built for observation of bridge system performance. The model contained the option to substitute any available deck system based on a subset of pre-calibrated parameters specific to each deck type. These alternative deck systems include an aluminum bridge deck system and a glass fiber reinforced plastic (GFRP) deck system. All three alternatives and the original steel grid deck system were evaluated based on the global responses of the moveable bridge, and the advantages and disadvantages of adopting the UHP-FRC deck system are quantified.
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Date Issued
2011
Identifier
CFE0003721, ucf:48803
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003721
STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS
Title
STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS.
Creator
Shmerling, Robert, Catbas, F. Necati, University of Central Florida
Abstract / Description
Objective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions...
Show moreObjective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions. The original analysis is based on certain simplifying assumptions such as rigid behavior over supports and simplified tendon/concrete/steel plate interaction. The current objective is to conduct a representative study for a more accurate understanding of the structural system and its behavior. The scope of the study is to generate finite element models (FEMs) to be used in static and dynamic parameter sensitivity studies, as well load rating and reliability analysis of the structure. The FEMs are used for eigenvalue analysis and simulations. Parameter sensitivity studies consider the effect of changing critical parameters, including material properties, prestress loss, and boundary and continuity conditions, on the static and dynamic structural response. Load ratings are developed using an American Association for State Highway Transportation Officials Load and Resistance Factor Rating (AASHTO LRFR) approach. The reliability of the structural system is evaluated based on the data obtained from various finite element models. Recommendations for experimental validation of the FEM are presented. This study is expected to provide information to make better decisions for operations, maintenance and safety requirements; to be a benchmark for future studies, to establish a procedure and methodology for structural condition assessment, and to contribute to the general research body of knowledge in condition assessment and structural health monitoring.
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Date Issued
2005
Identifier
CFE0000658, ucf:46520
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000658
Structural Identification through Monitoring, Modeling and Predictive Analysis under Uncertainty
Title
Structural Identification through Monitoring, Modeling and Predictive Analysis under Uncertainty.
Creator
Gokce, Hasan, Catbas, Fikret, Chopra, Manoj, Mackie, Kevin, Yun, Hae-Bum, DeMara, Ronald, University of Central Florida
Abstract / Description
Bridges are critical components of highway networks, which provide mobility and economical vitality to a nation. Ensuring the safety and regular operation as well as accurate structural assessment of bridges is essential. Structural Identification (St-Id) can be utilized for better assessment of structures by integrating experimental and analytical technologies in support of decision-making. St-Id is defined as creating parametric or nonparametric models to characterize structural behavior...
Show moreBridges are critical components of highway networks, which provide mobility and economical vitality to a nation. Ensuring the safety and regular operation as well as accurate structural assessment of bridges is essential. Structural Identification (St-Id) can be utilized for better assessment of structures by integrating experimental and analytical technologies in support of decision-making. St-Id is defined as creating parametric or nonparametric models to characterize structural behavior based on structural health monitoring (SHM) data. In a recent study by the ASCE St-Id Committee, St-Id framework is given in six steps, including modeling, experimentation and ultimately decision making for estimating the performance and vulnerability of structural systems reliably through the improved simulations using monitoring data. In some St-Id applications, there can be challenges and considerations related to this six-step framework. For instance not all of the steps can be employed; thereby a subset of the six steps can be adapted for some cases based on the various limitations. In addition, each step has its own characteristics, challenges, and uncertainties due to the considerations such as time varying nature of civil structures, modeling and measurements. It is often discussed that even a calibrated model has limitations in fully representing an existing structure; therefore, a family of models may be well suited to represent the structure's response and performance in a probabilistic manner.The principle objective of this dissertation is to investigate nonparametric and parametric St-Id approaches by considering uncertainties coming from different sources to better assess the structural condition for decision making. In the first part of the dissertation, a nonparametric St-Id approach is employed without the use of an analytical model. The new methodology, which is successfully demonstrated on both lab and real-life structures, can identify and locate the damage by tracking correlation coefficients between strain time histories and can locate the damage from the generated correlation matrices of different strain time histories. This methodology is found to be load independent, computationally efficient, easy to use, especially for handling large amounts of monitoring data, and capable of identifying the effectiveness of the maintenance. In the second part, a parametric St-Id approach is introduced by developing a family of models using Monte Carlo simulations and finite element analyses to explore the uncertainty effects on performance predictions in terms of load rating and structural reliability. The family of models is developed from a parent model, which is calibrated using monitoring data. In this dissertation, the calibration is carried out using artificial neural networks (ANNs) and the approach and results are demonstrated on a laboratory structure and a real-life movable bridge, where predictive analyses are carried out for performance decrease due to deterioration, damage, and traffic increase over time. In addition, a long-span bridge is investigated using the same approach when the bridge is retrofitted. The family of models for these structures is employed to determine the component and system reliability, as well as the load rating, with a distribution that incorporates various uncertainties that were defined and characterized. It is observed that the uncertainties play a considerable role even when compared to calibrated model-based predictions for reliability and load rating, especially when the structure is complex, deteriorated and aged, and subjected to variable environmental and operational conditions. It is recommended that a family-of-models approach is suitable for structures that have less redundancy, high operational importance, are deteriorated, and are performing under close capacity and demand levels.
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Date Issued
2012
Identifier
CFE0004232, ucf:48997
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004232
DIGITAL CONTROL OF HALF-BRIDGE DC-DC CONVERTERS WITH CURRENT DOUBLER RECTIFICATION
Title
DIGITAL CONTROL OF HALF-BRIDGE DC-DC CONVERTERS WITH CURRENT DOUBLER RECTIFICATION.
Creator
Yao, Liangbin, Batarseh, Issa, University of Central Florida
Abstract / Description
DC-DC power converters play an important role in powering telecom and computing systems. Complex systems, including power electronics systems, are increasingly using digital controllers because of the major advancements in digital controllers and DSP as well as there ability to perform sophisticated and enhanced control schemes. In this thesis, the digital controller is investigated for DC-DC converters in high current low voltage applications. For an optimal design of a regulated DC-DC...
Show moreDC-DC power converters play an important role in powering telecom and computing systems. Complex systems, including power electronics systems, are increasingly using digital controllers because of the major advancements in digital controllers and DSP as well as there ability to perform sophisticated and enhanced control schemes. In this thesis, the digital controller is investigated for DC-DC converters in high current low voltage applications. For an optimal design of a regulated DC-DC converter, it is necessary to derive a valid model. The current doubler rectified half bridge (CDRHB) DC-DC converter is suitable for high current low voltage applications. In this thesis, the topology operations are analyzed and then the unified state space model, analog small signal model and digital small signal model are derived. Then the digital compensator design is discussed as well as the analog-digital converter (ADC) and the digital pulse-width-modulator (DPWM) design rules. In addition, voltage driving optimization is proposed for the benefit of the digital controller. Finally, experimental results based on the CDRHB are presented and analyzed.
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Date Issued
2005
Identifier
CFE0000706, ucf:46626
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000706
TRANSFER AND DEVELOPMENT LENGTH OF STRANDS IN POST-TENSIONED MEMBERS AFTER ANCHOR HEAD FAILURE
Title
TRANSFER AND DEVELOPMENT LENGTH OF STRANDS IN POST-TENSIONED MEMBERS AFTER ANCHOR HEAD FAILURE.
Creator
El Zghayar, Elie, Mackie, Kevin, University of Central Florida
Abstract / Description
Post-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at...
Show morePost-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at the pier anchor location. Anchorage failure caused all PT force to transfer to the steel duct located within the pier segment that in turn slipped and caused the tendon to go completely slack. After the application of PT force, the anchorage assembly and steel pipes that house the tendon are filled with grout. These short grouted regions could, in the event of anchorage failure, provide a secondary anchorage mechanism preventing the scenario mentioned above from occurring. This paper presents the results of a full-scale experimental investigation on anchorage tendon pull-out and a finite element model to support the experimental results and interpretation. The study focuses on the length required to develop the in-service PT force within the pier segment grouted steel tube assembly. Seven, twelve, and nineteen 0.6ÂÂ" diameter strand tendons with various development lengths were considered. Recommendations for pier section pipe detailing and design will be discussed.
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Date Issued
2010
Identifier
CFE0003363, ucf:48465
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003363
Shifted Plastic Hinge Column Connections Using Grouted Sleeves for Accelerated Bridge Construction
Title
Shifted Plastic Hinge Column Connections Using Grouted Sleeves for Accelerated Bridge Construction.
Creator
Al-Jelawy, Haider, Mackie, Kevin, Gou, Jihua, Chopra, Manoj, University of Central Florida
Abstract / Description
Accelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research...
Show moreAccelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research consists of three components; testing of six large-scale precast reinforced concrete column models, a series of individual component tests on GS bar splices, and analytical studies. Large-scale, precast column models were designed and experimentally tested using a shifted plastic hinge (SPH) concept to minimize the damage in the capacity-protected elements and retain the column ductility. The column testing matrix considered aspect ratio, moment gradient, and splicing details. Column models were tested in an upright cantilever configuration under quasi-static cyclic load. Results showed that SPH can be used for both flexural and flexural-shear columns. Two types of component tests were performed: tensile tests to quantify the tensile behavior of the splices, and strain penetration tests to quantify the slip at the sleeve ends. The tests were used to obtain constitutive models for the bond-slip behavior of the GS splices.Results showed that GS splices developed the full ultimate stress of the spliced bars and that the slip at sleeve ends can considerably influence the global behavior of the precast columns. The analytical models were developed in OpenSees using fiber-based beams models and they incorporated the calibrated bond-slip models of GS splices. The large-scale column tests were simulated and compared with respective experimental results. Analytical results showed that the developed models were able to mimic the column behavior and can be used for analysis of GS precast columns.
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Date Issued
2017
Identifier
CFE0006851, ucf:51739
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006851
Computer Vision Based Structural Identification Framework for Bridge Health Mornitoring
Title
Computer Vision Based Structural Identification Framework for Bridge Health Mornitoring.
Creator
Khuc, Tung, Catbas, Necati, Oloufa, Amr, Mackie, Kevin, Zaurin, Ricardo, Shah, Mubarak, University of Central Florida
Abstract / Description
The objective of this dissertation is to develop a comprehensive Structural Identification (St-Id) framework with damage for bridge type structures by using cameras and computer vision technologies. The traditional St-Id frameworks rely on using conventional sensors. In this study, the collected input and output data employed in the St-Id system are acquired by series of vision-based measurements. The following novelties are proposed, developed and demonstrated in this project: a) vehicle...
Show moreThe objective of this dissertation is to develop a comprehensive Structural Identification (St-Id) framework with damage for bridge type structures by using cameras and computer vision technologies. The traditional St-Id frameworks rely on using conventional sensors. In this study, the collected input and output data employed in the St-Id system are acquired by series of vision-based measurements. The following novelties are proposed, developed and demonstrated in this project: a) vehicle load (input) modeling using computer vision, b) bridge response (output) using full non-contact approach using video/image processing, c) image-based structural identification using input-output measurements and new damage indicators. The input (loading) data due vehicles such as vehicle weights and vehicle locations on the bridges, are estimated by employing computer vision algorithms (detection, classification, and localization of objects) based on the video images of vehicles. Meanwhile, the output data as structural displacements are also obtained by defining and tracking image key-points of measurement locations. Subsequently, the input and output data sets are analyzed to construct novel types of damage indicators, named Unit Influence Surface (UIS). Finally, the new damage detection and localization framework is introduced that does not require a network of sensors, but much less number of sensors.The main research significance is the first time development of algorithms that transform the measured video images into a form that is highly damage-sensitive/change-sensitive for bridge assessment within the context of Structural Identification with input and output characterization. The study exploits the unique attributes of computer vision systems, where the signal is continuous in space. This requires new adaptations and transformations that can handle computer vision data/signals for structural engineering applications. This research will significantly advance current sensor-based structural health monitoring with computer-vision techniques, leading to practical applications for damage detection of complex structures with a novel approach. By using computer vision algorithms and cameras as special sensors for structural health monitoring, this study proposes an advance approach in bridge monitoring through which certain type of data that could not be collected by conventional sensors such as vehicle loads and location, can be obtained practically and accurately.
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Date Issued
2016
Identifier
CFE0006127, ucf:51174
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006127
STRUCTURAL HEALTH MONITORING WITH EMPHASIS ON COMPUTER VISION, DAMAGE INDICES, AND STATISTICAL ANALYSIS
Title
STRUCTURAL HEALTH MONITORING WITH EMPHASIS ON COMPUTER VISION, DAMAGE INDICES, AND STATISTICAL ANALYSIS.
Creator
ZAURIN, RICARDO, CATBAS, F. NECATI, University of Central Florida
Abstract / Description
Structural Health Monitoring (SHM) is the sensing and analysis of a structure to detect abnormal behavior, damage and deterioration during regular operations as well as under extreme loadings. SHM is designed to provide objective information for decision-making on safety and serviceability. This research focuses on the SHM of bridges by developing and integrating novel methods and techniques using sensor networks, computer vision, modeling for damage indices and statistical approaches....
Show moreStructural Health Monitoring (SHM) is the sensing and analysis of a structure to detect abnormal behavior, damage and deterioration during regular operations as well as under extreme loadings. SHM is designed to provide objective information for decision-making on safety and serviceability. This research focuses on the SHM of bridges by developing and integrating novel methods and techniques using sensor networks, computer vision, modeling for damage indices and statistical approaches. Effective use of traffic video synchronized with sensor measurements for decision-making is demonstrated. First, some of the computer vision methods and how they can be used for bridge monitoring are presented along with the most common issues and some practical solutions. Second, a conceptual damage index (Unit Influence Line) is formulated using synchronized computer images and sensor data for tracking the structural response under various load conditions. Third, a new index, Nd , is formulated and demonstrated to more effectively identify, localize and quantify damage. Commonly observed damage conditions on real bridges are simulated on a laboratory model for the demonstration of the computer vision method, UIL and the new index. This new method and the index, which are based on outlier detection from the UIL population, can very effectively handle large sets of monitoring data. The methods and techniques are demonstrated on the laboratory model for damage detection and all damage scenarios are identified successfully. Finally, the application of the proposed methods on a real life structure, which has a monitoring system, is presented. It is shown that these methods can be used efficiently for applications such as damage detection and load rating for decision-making. The results from this monitoring project on a movable bridge are demonstrated and presented along with the conclusions and recommendations for future work.
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Date Issued
2009
Identifier
CFE0002890, ucf:48039
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002890
Ultra-High Performance Concrete for Precast Seismic Bridge Column Connection
Title
Ultra-High Performance Concrete for Precast Seismic Bridge Column Connection.
Creator
Chan, Titchenda, Mackie, Kevin, Catbas, Necati, Chopra, Manoj, Bai, Yuanli, University of Central Florida
Abstract / Description
Accelerated bridge construction (ABC) utilizes prefabricated bridge elements constructed off-site, delivered, and assembled on-site to expedite construction time and reduce traffic disruption. ABC has been increasingly used for super- and sub-structure elements in low seismic regions. However, its application in medium and high seismic regions remain limited, particularly for precast columns where connections typically coincide with plastic hinge (PH) regions. Ultra-high performance concrete ...
Show moreAccelerated bridge construction (ABC) utilizes prefabricated bridge elements constructed off-site, delivered, and assembled on-site to expedite construction time and reduce traffic disruption. ABC has been increasingly used for super- and sub-structure elements in low seismic regions. However, its application in medium and high seismic regions remain limited, particularly for precast columns where connections typically coincide with plastic hinge (PH) regions. Ultra-high performance concrete (UHPC), characterized by high compressive and tensile strength, and superior bond properties, is a potential material that can mitigate PH damage and enhance load transfer. This research proposes a new and simple damage tolerant precast column connection for use in medium and high seismic regions. The connection laps the column longitudinal reinforcement with footing dowels using a short splice length, a practical concrete cover, no shear reinforcement, and the shifted PH concept to prevent footing damage. Two 0.42-scale precast columns with different shear span ratios were tested under reversed cyclic loading to investigate the proposed connection relative to previously tested cast-in-place specimens. Results showed the connection performed well in shear, developed column longitudinal bars, shifted PH formation above the UHPC connection, and exhibited high lateral capacity and ductility. Twenty-seven pullout and lap splice beams were tested to study the bond of reinforcement in UHPC under different parameters and stress states. Results indicated significant bond strength improvement and splice length reduction compared with conventional concrete. The pullout specimens were simulated using the OpenSees framework to propose reinforcing steel in UHPC bond-slip models where existing studies in the literature were limited. The models were incorporated into the numerical modeling of the precast columns using one-dimensional fiber-section and two-dimensional plane stress nonlinear analyses. Results from the two modeling methods showed good agreement with the experiments, with the calibrated bond-slip models providing a good representation of load transfer in the connection.
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Date Issued
2019
Identifier
CFE0007610, ucf:52534
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007610
Design Optimization of LLC Topology and Phase Skipping Control of Three Phase Inverter for PV Applications
Title
Design Optimization of LLC Topology and Phase Skipping Control of Three Phase Inverter for PV Applications.
Creator
Somani, Utsav, Batarseh, Issa, Wu, Xinzhang, Seyedi-Esfahani, Seyed-alireza, University of Central Florida
Abstract / Description
The world is heading towards an energy crisis and desperate efforts are being made to find an alternative, reliable and clean source of energy. Solar Energy is one of the most clean and reliable source of renewable energy on earth. Conventionally, extraction of solar power for electricity generation was limited to PV farms, however lately Distributed Generation form of Solar Power has emerged in the form of residential and commercial Grid Tied Micro-Inverters. Grid Tied Micro-Inverters are...
Show moreThe world is heading towards an energy crisis and desperate efforts are being made to find an alternative, reliable and clean source of energy. Solar Energy is one of the most clean and reliable source of renewable energy on earth. Conventionally, extraction of solar power for electricity generation was limited to PV farms, however lately Distributed Generation form of Solar Power has emerged in the form of residential and commercial Grid Tied Micro-Inverters. Grid Tied Micro-Inverters are costly when compared to their string type counterparts because one inverter module is required for every single or every two PV panels whereas a string type micro-inverter utilizes a single inverter module over a string of PV panels. Since in micro-inverter every panel has a dedicated inverter module, more power per panel can be extracted by performing optimal maximum power tracking over single panel rather than over an entire string of panels. Power per panel extracted by string inverters may be lower than its maximum value as few of the panels in the string may or may not be shaded and thereby forming the weaker links of the system.In order to justify the higher costs of Micro-Inverters, it is of utmost importance to convert the available power with maximum possible efficiency. Typically, a micro-inverter consists of two important blocks; a Front End DC-DC Converter and Output DC-AC Inverter. This thesis proposes efficiency optimization techniques for both the blocks of the micro-inverter. Efficiency Optimization of Front End DC-DC Converter-This thesis aims to optimize the efficiency of the front end stage by proposing optimal design procedure for resonant parameters of LLC Topology as a Front End DC-DC Converter for PV Applications. It exploits the I-V characteristics of a solar panel to design the resonant parameters such that resonant LLC topology operates near its resonant frequency operating point which is the highest efficiency operating point of LLC Converter.Efficiency Optimization of Output DC-AC Inverter-Due to continuously variable irradiance levels of solar energy, available power for extraction is constantly varying which causes the PV Inverter operates at its peak load capacity for less than 15% of the day time. Every typical power converter suffers through poor light load efficiency performance because of the load independent losses present in a power converter. In order to improve the light load efficiency performance of Three Phase Inverters, this thesis proposes Phase Skipping Control technique for Three Phase Grid Tied Micro-Inverters. The proposed technique is a generic control technique and can be applied to any inverter topology, however, in order to establish the proof of concept this control technique has been implemented on Three Phase Half Bridge PWM Inverter and its analysis is provided. Improving light load efficiency helps to improve the CEC efficiency of the inverter.
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Date Issued
2013
Identifier
CFE0005265, ucf:50573
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005265
HIGH CURRENT DENSITY LOW VOLTAGE ISOLATED DC-DC CONVERTERSWITH FAST TRANSIENT RESPONSE
Title
HIGH CURRENT DENSITY LOW VOLTAGE ISOLATED DC-DC CONVERTERSWITH FAST TRANSIENT RESPONSE.
Creator
Yao, Liangbin, Batarseh, Issa, University of Central Florida
Abstract / Description
With the rapid development of microprocessor and semiconductor technology, industry continues to update the requirements for power supplies. For telecommunication and computing system applications, power supplies require increasing current level while the supply voltage keeps decreasing. For example, the Intel's CPU core voltage decreased from 2 volt in 1999 to 1 volt in 2005 while the supply current increased from 20A in 1999 to up to 100A in 2005. As a result, low-voltage high-current...
Show moreWith the rapid development of microprocessor and semiconductor technology, industry continues to update the requirements for power supplies. For telecommunication and computing system applications, power supplies require increasing current level while the supply voltage keeps decreasing. For example, the Intel's CPU core voltage decreased from 2 volt in 1999 to 1 volt in 2005 while the supply current increased from 20A in 1999 to up to 100A in 2005. As a result, low-voltage high-current high efficiency dc-dc converters with high power-density are demanded for state-of-the-art applications and also the future applications. Half-bridge dc-dc converter with current-doubler rectification is regarded as a good topology that is suitable for high-current low-voltage applications. There are three control schemes for half-bridge dc-dc converters and in order to provide a valid unified analog model for optimal compensator design, the analog state-space modeling and small signal modeling are studied in the dissertation and unified state-space and analog small signal model are derived. In addition, the digital control gains a lot of attentions due to its flexibility and re-programmability. In this dissertation, a unified digital small signal model for half-bridge dc-dc converter with current doubler rectifier is also developed and the digital compensator based on the derived model is implemented and verified by the experiments with the TI DSP chip. In addition, although current doubler rectifier is widely used in industry, the key issue is the current sharing between two inductors. The current imbalance is well studied and solved in non-isolated multi-phase buck converters, yet few discusse this issue in the current doubler rectification topology within academia and industry. This dissertation analyze the current sharing issue in comparison with multi-phase buck and one modified current doubler rectifier topology is proposed to achieve passive current sharing. The performance is evaluated with half bridge dc-dc converter; good current sharing is achieved without additional circuitry. Due to increasing demands for high-efficiency high-power-density low-voltage high current topologies for future applications, the thermal management is challenging. Since the secondary-side conduction loss dominates the overall power loss in low-voltage high-current isolated dc-dc converters, a novel current tripler rectification topology is proposed. Theoretical analysis, comparison and experimental results verify that the proposed rectification technique has good thermal management and well-distributed power dissipation, simplified magnetic design and low copper loss for inductors and transformer. That is due to the fact that the load current is better distributed in three inductors and the rms current in transformer windings is reduced. Another challenge in telecommunication and computing applications is fast transient response of the converter to the increasing slew-rate of load current change. For instance, from Intel's roadmap, it can be observed that the current slew rate of the age regulator has dramatically increased from 25A/uS in 1999 to 400A/us in 2005. One of the solutions to achieve fast transient response is secondary-side control technique to eliminate the delay of optocoupler to increase the system bandwidth. Active-clamp half bridge dc-dc converter with secondary-side control is presented and one industry standard 16th prototype is built and tested; good efficiency and transient response are shown in the experimental section. However, one key issue for implementation of secondary-side control is start-up. A new zero-voltage-switching buck-flyback isolated dc-dc converter with synchronous rectification is proposed, and it is only suitable for start-up circuit for secondary-side controlled converter, but also for house-keeping power supplies and standalone power supplies requiring multi-outputs.
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Date Issued
2007
Identifier
CFE0001814, ucf:47336
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001814
Uncertainty treatment in performance based seismic assessment of typical bridge classes in United States
Title
Uncertainty treatment in performance based seismic assessment of typical bridge classes in United States.
Creator
Mehdizadeh Nasrabadi, Mohammad, Mackie, Kevin, Catbas, Necati, Yun, Hae-Bum, Xanthopoulos, Petros, University of Central Florida
Abstract / Description
Bridge networks are expensive and complex infrastructures and are essential components of today's transportation systems. Despite the advancement in computer aided modeling and increasing the computational power which is increasing the accessibility for developing the fragility curves of bridges, the complexity of the problem and uncertainties involved in fragility analysis of the bridge structures in addition to difficulties in validating the results obtained from the analysis requires...
Show moreBridge networks are expensive and complex infrastructures and are essential components of today's transportation systems. Despite the advancement in computer aided modeling and increasing the computational power which is increasing the accessibility for developing the fragility curves of bridges, the complexity of the problem and uncertainties involved in fragility analysis of the bridge structures in addition to difficulties in validating the results obtained from the analysis requires precaution in utilization of the results as a decision making tool. The main focus of this research is to address, study and treatment of uncertainties incorporated in various steps of performance based assessments (PBA) of the bridge structures. In this research the uncertainties is divided into three main categories. First, the uncertainties that come from ground motions time and frequency content alteration because of scarcity of the recorded ground motions in the database. Second, uncertainties associated in the modeling and simulation procedure of PBA, and third uncertainties originated from simplistic approach and methods utilized in the conventional procedure of PBA of the structures. Legitimacy of the scaling of ground motions is studied using the response of several simple nonlinear systems to amplitude scaled ground motions suites. Bias in the response obtained compared to unscaled records for both as recorded and synthetic ground motions.Results from this section of the research show the amount of the bias is considerable and can significantly affect the outcome of PBA. The origin of the bias is investigated and consequently a new metric is proposed to predict the bias induced by ground motion scaling without nonlinear analysis. Results demonstrate that utilizing the predictor as a scaling parameter can significantly reduce the bias for various nonlinear structures. Therefore utilizing the new metric as the intensity measuring parameter of the ground motions is recommended in PBA. To address the uncertainties associated in the modeling and simulation, MSSS concrete girder bridge class were selected due to the frequency of the construction in USCS region and lack of seismic detailing. A large scale parameters screening study is performed using Placket-Burman experimental design that considers a more complete group of parameters to decrease the computational expense of probabilistic study of the structure's seismic response. Fragility analysis for MSSS bridge is performed and the effect of removing the lesser important parameters the probabilistic demand model was investigated. This study reveals parameters reduction based on screening study techniques can be utilized to increase efficiency in fragility analysis procedure without compromising the accuracy of the outcome. The results from this study also provides more direct information on parameter reduction for PBA as well as provide insight into where future investments into higher fidelity finite element and constitutive models should be targeted. Conventional simplistic PBA approach does not account for the fundamental correlation between demand and capacity models. A more comprehensive PBA approach is presented and fragility analysis is performed with implementation of a new formulation in the component fragility analysis for MSSS bridge class and the outcome is compared with the one from conventional procedure. The results shows the correlation between demand and capacity affects the outcome of PBA and the fragility functions variation is not negligible. Therefore using the presented approach is necessary when accuracy is needed.
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Date Issued
2014
Identifier
CFE0005531, ucf:50309
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005531
Design and Implementation of PV-Firming and Optimization Algorithms For Three-Port Microinverters
Title
Design and Implementation of PV-Firming and Optimization Algorithms For Three-Port Microinverters.
Creator
Alharbi, Mahmood, Batarseh, Issa, Haralambous, Michael, Mikhael, Wasfy, Yuan, Jiann-Shiun, Kutkut, Nasser, University of Central Florida
Abstract / Description
With the demand increase for electricity, the ever-increasing awareness of environmental issues, coupled with rolling blackouts, the role of renewable energy generation is increasing along with the thirst for electricity and awareness of environmental issues. This dissertation proposes the design and implementation of PV-firming and optimization algorithms for three-port microinverters.Novel strategies are proposed in Chapters 3 and 4 for harvesting stable solar power in spite of intermittent...
Show moreWith the demand increase for electricity, the ever-increasing awareness of environmental issues, coupled with rolling blackouts, the role of renewable energy generation is increasing along with the thirst for electricity and awareness of environmental issues. This dissertation proposes the design and implementation of PV-firming and optimization algorithms for three-port microinverters.Novel strategies are proposed in Chapters 3 and 4 for harvesting stable solar power in spite of intermittent solar irradiance. PV firming is implemented using a panel-level three-port grid-tied PV microinverter system instead of the traditional high-power energy storage and management system at the utility scale. The microinverter system consists of a flyback converter and an H-bridge inverter/rectifier, with a battery connected to the DC-link. The key to these strategies lies in using static and dynamic algorithms to generate a smooth PV reference power. The outcomes are applied to various control methods to charge/discharge the battery so that a stable power generation profile is obtained. In addition, frequency-based optimization for the inverter stage is presented.One of the design parameters of grid-tied single-phase H-bridge sinusoidal pulse-width modulation (SPWM) microinverters is switching frequency. The selection of the switching frequency is a tradeoff between improving the power quality by reducing the total harmonic distortion (THD), and improving the efficiency by reducing the switching loss. In Chapter 5, two algorithms are proposed for optimizing both the power quality and the efficiency of the microinverter. They do this by using a frequency tracking technique that requires no hardware modification. The first algorithm tracks the optimal switching frequency for maximum efficiency at a given THD value. The second maximizes the power quality of the H-bridge micro-inverter by tracking the switching frequency that corresponds to the minimum THD.Real-time PV intermittency and usable capacity data were evaluated and then further analyzed in MATLAB/SIMULINK to validate the PV firming control. The proposed PV firming and optimization algorithms were experimentally verified, and the results evaluated. Finally, Chapter 6 provides a summary of key conclusions and future work to optimize the presented topology and algorithms.
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Date Issued
2018
Identifier
CFE0007305, ucf:52166
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007305
Investigation of infrared thermography for subsurface damage detection of concrete structures
Title
Investigation of infrared thermography for subsurface damage detection of concrete structures.
Creator
Hiasa, Shuhei, Catbas, Necati, Tatari, Omer, Nam, Boo Hyun, Zaurin, Ricardo, Xanthopoulos, Petros, University of Central Florida
Abstract / Description
Deterioration of road infrastructure arises from aging and various other factors. Consequently, inspection and maintenance have been a serious worldwide problem. In the United States, degradation of concrete bridge decks is a widespread problem among several bridge components. In order to prevent the impending degradation of bridges, periodic inspection and proper maintenance are indispensable. However, the transportation system faces unprecedented challenges because the number of aging...
Show moreDeterioration of road infrastructure arises from aging and various other factors. Consequently, inspection and maintenance have been a serious worldwide problem. In the United States, degradation of concrete bridge decks is a widespread problem among several bridge components. In order to prevent the impending degradation of bridges, periodic inspection and proper maintenance are indispensable. However, the transportation system faces unprecedented challenges because the number of aging bridges is increasing under limited resources, both in terms of budget and personnel. Therefore, innovative technologies and processes that enable bridge owners to inspect and evaluate bridge conditions more effectively and efficiently with less human and monetary resources are desired. Traditionally, qualified engineers and inspectors implemented hammer sounding and/or chain drag, and visual inspection for concrete bridge deck evaluations, but these methods require substantial field labor, experience, and lane closures for bridge deck inspections. Under these circumstances, Non-Destructive Evaluation (NDE) techniques such as computer vision-based crack detection, impact echo (IE), ground-penetrating radar (GPR) and infrared thermography (IRT) have been developed to inspect and monitor aging and deteriorating structures rapidly and effectively. However, no single method can detect all kinds of defects in concrete structures as well as the traditional inspection combination of visual and sounding inspections; hence, there is still no international standard NDE methods for concrete bridges, although significant progress has been made up to the present.This research presents the potential to reduce a burden of bridge inspections, especially for bridge decks, in place of traditional chain drag and hammer sounding methods by IRT with the combination of computer vision-based technology. However, there were still several challenges and uncertainties in using IRT for bridge inspections. This study revealed those challenges and uncertainties, and explored those solutions, proper methods and ideal conditions for applying IRT in order to enhance the usability, reliability and accuracy of IRT for concrete bridge inspections. Throughout the study, detailed investigations of IRT are presented. Firstly, three different types of infrared (IR) cameras were compared under active IRT conditions in the laboratory to examine the effect of photography angle on IRT along with the specifications of cameras. The results showed that when IR images are taken from a certain angle, each camera shows different temperature readings. However, since each IR camera can capture temperature differences between sound and delaminated areas, they have a potential to detect delaminated areas under a given condition in spite of camera specifications even when they are utilized from a certain angle. Furthermore, a more objective data analysis method than just comparing IR images was explored to assess IR data. Secondly, coupled structural mechanics and heat transfer models of concrete blocks with artificial delaminations used for a field test were developed and analyzed to explore sensitive parameters for effective utilization of IRT. After these finite element (FE) models were validated, critical parameters and factors of delamination detectability such as the size of delamination (area, thickness and volume), ambient temperature and sun loading condition (different season), and the depth of delamination from the surface were explored. This study presents that the area of delamination is much more influential in the detectability of IRT than thickness and volume. It is also found that there is no significant difference depending on the season when IRT is employed. Then, FE model simulations were used to obtain the temperature differences between sound and delaminated areas in order to process IR data. By using this method, delaminated areas of concrete slabs could be detected more objectively than by judging the color contrast of IR images. However, it was also found that the boundary condition affects the accuracy of this method, and the effect varies depending on the data collection time. Even though there are some limitations, integrated use of FE model simulation with IRT showed that the combination can be reduce other pre-tests on bridges, reduce the need to have access to the bridge and also can help automate the IRT data analysis process for concrete bridge deck inspections. After that, the favorable time windows for concrete bridge deck inspections by IRT were explored through field experiment and FE model simulations. Based on the numerical simulations and experimental IRT results, higher temperature differences in the day were observed from both results around noontime and nighttime, although IRT is affected by sun loading during the daytime heating cycle resulting in possible misdetections. Furthermore, the numerical simulations show that the maximum effect occurs at night during the nighttime cooling cycle, and the temperature difference decreases gradually from that time to a few hours after sunrise of the next day. Thus, it can be concluded that the nighttime application of IRT is the most suitable time window for bridge decks. Furthermore, three IR cameras with different specifications were compared to explore several factors affecting the utilization of IRT in regards to subsurface damage detection in concrete structures, specifically when the IRT is utilized for high-speed bridge deck inspections at normal driving speeds under field laboratory conditions. The results show that IRT can detect up to 2.54 cm delamination from the concrete surface at any time period. This study revealed two important factors of camera specifications for high-speed inspection by IRT as shorter integration time and higher pixel resolution.Finally, a real bridge was scanned by three different types of IR cameras and the results were compared with other NDE technologies that were implemented by other researchers on the same bridge. When compared at fully documented locations with 8 concrete cores, a high-end IR camera with cooled detector distinguished sound and delaminated areas accurately. Furthermore, indicated location and shape of delaminations by three IR cameras were compared to other NDE methods from past research, and the result revealed that the cooled camera showed almost identical shapes to other NDE methods including chain drag. It should be noted that the data were collected at normal driving speed without any lane closures, making it a more practical and faster method than other NDE technologies. It was also presented that the factor most likely to affect high-speed application is integration time of IR camera as well as the conclusion of the field laboratory test.The notable contribution of this study for the improvement of IRT is that this study revealed the preferable conditions for IRT, specifically for high-speed scanning of concrete bridge decks. This study shows that IRT implementation under normal driving speeds has high potential to evaluate concrete bridge decks accurately without any lane closures much more quickly than other NDE methods, if a cooled camera equipped with higher pixel resolution is used during nighttime. Despite some limitations of IRT, the data collection speed is a great advantage for periodic bridge inspections compared to other NDE methods. Moreover, there is a high possibility to reduce inspection time, labor and budget drastically if high-speed bridge deck scanning by the combination of IRT and computer vision-based technology becomes a standard bridge deck inspection method. Therefore, the author recommends combined application of the high-speed scanning combination and other NDE methods to optimize bridge deck inspections.
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Date Issued
2016
Identifier
CFE0006323, ucf:51575
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006323