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1
Hedlund, Nadja. "Non-Destructive Testing Of Concrete Bridges". Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81923.
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Non-destructive testing is of great value in cases where a structure's future is investigated to find out what the best measure is. It is not always the best solution to demolish and build new. Many structures can be repaired and function several more years. In this thesis the main goal is to investigate some different non-destructive techniques and learn more about difficulties and strengths. The test subjects will be a cast T-beam in a laboratory environment as well as a case study of a railway bridge in Abisko. The different testing equipment being used in this thesis is a covermeter, a rebound hammer and ultrasonic pulse velocity. For both the T-beam and the bridge the results are overall very good. The covermeter is proven to be both easy to use and very reliable and the ultrasonic pulse velocity was more to learn about and more difficult but is giving very good results as well. Conclusions after the thesis project is that it requires a lot of experience of the user and time to make non-destructive testing useful and competitive in the society. Getting all the pieces together it is a powerful tool that hopefully is a sustainable asset in the future, regarding both economic and environmental issues.
2
Kgoboko, Kobamelo. "Collapse behaviour of non-ductile partially prestressed concrete bridge girders". Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09EN/09enk445.pdf.
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Slapkus, Adam. "Evaluation of Georgia's high performance concerete bridge". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19479.
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Smolenski, Peter James. "Field instrumentation and live load testing to evaluate behaviors of three reinforced concrete bridge decks". Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/smolenski/SmolenskiP0805.pdf.
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Dupuis, Kenneth J. "Nondestructive testing of concrete box girder bridges using thermal imaging". Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Spring2008/K_Dupuis_040908.pdf.
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Sasher, William C. "Testing, assessment and FRP strengthening of concrete T-beam bridges in Pennsylvania". Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5876.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains viii, 177 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 130-136).
7
Ferdjani, Omar. "Behaviour of a one cell prestressed concrete box girder bridge : analytical study". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66163.
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Igwemezie, Jude O. "Dynamic response and impact effects in precast, prestressed concrete bridge ties". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74056.
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Rubin, Ariel. "Strenghtening of reinforced concrete bridge decks with carbon fiber composites". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19320.
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Khaled, Amar. "Behaviour of a two-cell prestressed concrete box girder bridge : analytical study". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64019.
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Joucdar, Karim. "Behaviour of a two-cell prestressed concrete box girder bridge : experimental study". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63981.
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Shams, Mohamed Khalil. "Time-dependent behavior of high-performance concrete". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20682.
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Justice, Adam L. "Testing and assessment of FRP strengthened concrete T-beam bridges in Pennsylvania". Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11255.
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Thesis (M.S.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains ix, 223 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-141).
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Maguire, Marcus J. "Transverse and Longitudinal Bending of Segmental Concrete Box Girder Bridges". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23670.
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Post-tensioned segmental concrete box girders have been in use in the United States since the early 1970s. This unique bridge system uses post-tensioning to connect many smaller concrete bridge segments into very efficient long span bridges. However, because of the slender components, localized transverse bending becomes more critical when compared to more conventional bridge types. Bridge owners are finding that ratings for standard loads and permit trucks are often controlled by the transverse behavior of the girders near concentrated wheel loads. The popular analysis methods used today range from two dimensional frame models to three dimensional finite element models of the entire bridge. Currently, engineers must make sound engineering judgments on limited available information, while balancing safety and economy. To quantify and understand longitudinal and transverse behavior, the results from three live load tests of single cell segmental concrete box girder bridges are presented. Each bridge was instrumented with longitudinal and transverse strain sensors on at least two cross sections as well as rotation and deflection sensors, when possible. Two dimensional transverse frame models and three dimensional shell models were compared to the test results for each subject bridge. The two dimensional frame analyses using the common bottom web pin and roller boundary conditions provide mean absolute percent error in excess of 250%. Conversely, the newly introduced boundary conditions using pin supports at the top and bottom of each web was shown to reduce mean absolute percent error to 82%, which is on the same order of magnitude as longitudinal beamline analysis.
The three dimensional shell models were insensitive to several changes including mesh fineness, number of spans modeled, and support conditions. Using uniform surface loading, the transverse modeling procedure was shown to provide significantly more accurate results than the common two dimensional frame models. A faster and more convenient analysis method using a program generated, structure specific, influence surface was also outlined. This method produced similar results when compared to the uniform surface loading method, while allowing additional automation for easier load application.
Ph. D.
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Haines, Robert Anthony. "Shear Testing of Prestressed High Performance Concrete Bridge Girders". Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7120.
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This report details the design and construction of an AASHTO Type IV prestressed girder and a PCI BT-56 prestressed girder. It also details the shear testing and shear performance of the BT-56 girder. The results are compared with results from previous research dating back to 1986. Finally, all research was compared with the AASHTO Standard (2002), AASHTO LRFD (1998) and AASHTO LRFD (2004) Specifications to examine thier overall accuracy in predicting shear strengths.
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Fason, William Ernest Barnes Robert W. "Static load testing of a damaged, continuous prestressed concrete bridge". Auburn, Ala, 2009. http://hdl.handle.net/10415/1582.
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Cook, Wesley J. "Destructive Testing of Composite Precast Concrete Deck Panels and Buil-up Steel Plate Girders". DigitalCommons@USU, 2010. http://digitalcommons.usu.edu/etd/946.
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The Utah Department of Transportation (UDOT) has implemented the use of precast concrete panels for bridge deck construction. A bridge utilizing these panels as a reconstruction method was decommissioned three years after the new deck installation, due to unrelated matters. Two sections of this bridge were salvaged and sent to Utah State University (USU) for destructive testing.
Each bridge section consisted of two built-up steel plate girders intact with the precast concrete deck panels. The precast panels were designed and constructed to achieve full composite action between the deck and built-up steel plate girders through the use of Nelson shear studs. Additionally, the precast panels span the transverse direction and as such have a transverse joint. Historic data has shown the transverse joint to be an area of concern for the functionality of the structural system.
Flexure, beam shear, and punching shear of the deck ultimate capacities were compared to those calculated in accordance to the AASTHO Load and Resistance Factor Design (LRFD) Bridge Design Specifications. Various experimental tests considered the affects of the transverse joint on the elastic and plastic capacities and code adherence. Nine destructive tests were performed. The Nelson shear studs were found to be capable of achieving the ultimate capacities of all three types of performed tests and therefore a significant level composite action was attained throughout the experimental tests. The transverse joints show a slight decrease in flexural elastic capacity, no measurable influence on flexural plastic capacity and beam shear ultimate capacity, and a 40% decrease to ultimate punching shear capacity to the deck compared to punching shear capacity without a transverse joint.
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Thornton, Nathan Paul. "Live Load Testing of Appalachia, Va Concrete Arch Bridges for Load Rating Recommendation". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/35195.
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As Americaâ s infrastructure ages, many of the nationâ s bridges approach the end of their service life. In order to develop a method for handling the rising number of deficient and functionally obsolete bridges, nondestructive tests and evaluations must be undertaken. Valuable information from these tests regarding the strength and condition of bridges will help in making decisions about their rehabilitation and replacement. Two adjoining open spandrel reinforced concrete arch bridges in downtown Appalachia, Virginia were selected for live load testing by Virginia Department of Transportation (VDOT). Both bridges have supported an increasing amount of extreme coal truck traffic throughout their service life and are essential to the efficient transport of coal in the region. Because of their age, having been built in 1929, and the amount of visible damage and repairs, VDOT was concerned about their remaining capacity and safe operation.
The live load tests focused on global behavior characteristics such as service strain and deflection as well as local behavior of the arches surrounding significant repairs. It was found that the strain and deflection data collected during load testing displayed linear elastic behavior, indicating excess capacity beyond the test loads. Also, given the loading applied, the measured strains and deflections were small in magnitude, showing that the bridges are still acting as stiff structures and are in good condition.
Data collected during these tests was compared to results from a finite element model of the bridges to determine the coal truck size which is represented by the live load test loading configurations. The model comparisons determined the test loads produced comparable deflections to those produced by the target coal truck load. Through this approach, a recommendation was given to VDOT regarding the satisfactory condition of the aging bridges to aid in the process of load rating and maintenance scheduling for the two bridges.
Master of Science
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Nilimaa, Jonny. "Upgrading concrete bridges : post-tensioning for higher loads". Licentiate thesis, Luleå tekniska universitet, Byggkonstruktion och -produktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25964.
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There are a great number of old structures around the world, some of which were designed for completely different purposes than in their current application. Swedish railway bridges were for example only designed for maximum axle loads of 200 kN in the beginning of the 20th century, while the highest axle loads of today are twice as high. The traffic intensities have also increased dramatically and the velocities are now higher than ever before. Reinforced concrete trough bridges were typically designed and built in the mid-20th century and it is still one of the most frequent railway bridge types in Sweden. The trough bridges were normally designed for traffic loads which were smaller than the loads today and in order to maintain an old structure as the loads increases, structural upgrading of the load bearing capacity might be necessary. Upgrading the load carrying capacity can be performed in two ways, namely administrative upgrading or strengthening. Administrative upgrading refers to refined design calculations, using real material data, geometry and loads, which provides a higher capacity than the original design and the bridge can thereby be upgrading with minor physical impact. Upgrading by strengthening on the other hand, refers to, often, larger physical alteration of the structure in order to enhance the original load carrying capacity.Upgrading methods for increased flexural resistance of concrete trough bridges has been developed and tested previously, but strengthening methods for increased shear resistance in the bridge deck are still absent. The objective of this thesis is therefore to find an existing- or develop a new strengthening method which can be applied in order to enhance the shear resistance of concrete trough bridge decks. The difficulties associated to strengthening of existing railway bridges include traffic during the strengthening work and concrete surfaces concealed by the ballast.The State-of-the-Art indicated that none of the existing strengthening techniques were sufficient for this application and internal unbonded post-tensioning in the transverse direction was nominated as the most promising method. The research was thereafter focused on testing the possibilities and strengthening effects of post-tensioning. Two laboratory investigations were performed during the research project and the method was finally tested in a field test on a 50 years old trough bridge in Haparanda, Sweden. The strengthening procedure of internal unbonded post-tensioning consists of four consecutive steps:1.Transverse drilling of the horizontal holes through the bottom slab.2.Installation of the prestressing system.3.Post-tensioning of the system.4.Sealing of the prestressing system.The laboratory and field tests were successful and the results proved that the internal steel reinforcement within the concrete was compressed when the trough bridge was post-tensioned. Due to the compression, a higher load could be carried by the bridge deck before the tensile reinforcement yields and the bridge fails. In other words, the flexural capacity of the bridge deck was increased. The field test actually showed that eight steel bars, post-tensioned with 430 kN per bar on the Haparanda Bridge, completely counteracted the tensile stresses caused by a train with 215 kN axle loads. The effect on the shear resistance was however not as easy to measure, but the laboratory test recorded a significant strain reduction in the tensile reinforcement which was bent up at the transition zone between the bridge deck and the main girders. The reduced strain might be interpreted as lower shear stresses and post-tensioning can thereby be considered to have a positive effect on the shear resistance of the bridge deck. Shear design according to the protocol of Eurocode 2 or BBK was however found to be restrictive in predicting the post-tensionings effect on the shear capacity and further research is proposed in chapter 8.Det finns ett stort antal gamla konstruktioner runtom i världen och många byggdes för helt andra användningsområden än vad de numera används till. Som ett exempel kan nämnas att svenska järnvägsbroar i början av 1900-talet byggdes för att klara av att bära axellaster på maximalt 200 kN, medan några av våra nybyggda broar är konstruerade för dubbelt så stora axellaster. Även traffikmängden har mångdubblats och tåghastigheterna är nu högre än någonsin. Trågbroar i armerad betong är en typisk bro som byggdes i Sverige framförallt på 50-talet och den är fortfarande en av de vanligaste brotyperna i Sverige. Trågbroarna konstruerades normalt för att bära lägre laster än vad vi har idag och för att kunna ha kvar dessa broar när lasterna ökar kan det krävas någon form av uppgradering av bärförmågan. Det finns två sätt att förbättra bärförmågan på en gammal bro, nämligen administrativ uppgradering eller förstärkning. Administrativ uppgradering innebär att nya förbättrade beräkningsmetoder används tillsammans med verkliga materialhållfastheter, geometrier och laster för att mer noggrant räkna ut brons bärförmåga. Normalt visar det sig att bärförmågan är högre än vad de ursprungliga beräkningarna antydde. På så vis höjs kapaciteten med minimal fysisk åverkan på bron. Uppgradering genom förstärkning innebär däremot att konstruktionens bärförmåga höjs genom att förändra bron ur ett rent fysiskt perspektiv. Metoder för att öka böjkapaciteten på trågbroar i betong har utvecklats och testats tidigare, men förstärkningsmetoder för att höja tvärkraftskapaciteten saknas däremot fortfarande. Målet för denna avhandling ligger därför i att utveckla en förstärkningsmetod som kan användas för att förbättra tvärkraftskapaciteten för bottenplattan på trågbroar i betong. Det finns dock några svårigheter sammankopplade med förstärkning av befintliga järnvägsbroar, t.ex. tågtraffik under förstärkningsförfarandet och att viktiga betongytor är skyddade av ballast.Inga befintliga förstärkningsmetoder bedömdes däremot som lämpliga för det avsedda användningsområdet vid ”State-of-the-Art’’ studien. Invändig efterspänning av broplattan i tvärledd bedömdes som den bäst lämpade förstärkningsmetoden och efterföljande forskning fokuserades på att reda ut möjligheter för och förstärkningseffekter av efterspänning. Två olika laboratorieförsök genomfördes under forskningsprojektet och förstärkningsmetoden testades slutligen vid ett fältförsök på en 50 år gammal järnvägsbro i Haparanda.Själva tillvägagångssättet för förstärkningsmetoden består av fyra viktigaoch sammanhängande arbetssteg:1. Borrning av horisontella hål tvärs igenom trågbrons bottenplatta.2. Installation av själva försstärkningssystemet.3. Efterspänning av förstärkningssystemet.4. Förslutning av förstärkningssystemet.Både laboratorie och fältförsöken blev lyckade och resultaten visade att stålarmeringen inuti betongen trycktes ihop när trågbron efterspänndes. Tack vare denna kompression så kan broplattan bära högre laster innan dragarmeringen börjar flyta och bron slutligen går sönder. Med andra ord så höjdes brons böjkapacitet. Fältförsöket visade att de åtta spännstagen, efterspännda med 430 kN per stag, helt och hållet motverkade dragarmeringens påkänningar av ett tåg med axellasten 215 kN. Förstärkningsmetodens effekt på tvärkraftskapaciteten är däremot inte lika lätt att påvisa men laboratorieförsöken visade att töjningen reducerades betydligt i den uppbockade dragarmeringen, i zonen där plattan fäster i huvudbalkarna. De lägre töjningsnivåerna kan tolkas som lägre skjuvpåkänningar och efterspänningen kan därmed ha en positiv effekt på broplattans tvärkraftskapacitet. Laboratorieförsöken visade däremot att både Eurokod 2 och BBK är restriktiva när det gäller att uppskatta efterspänningens effekt på tvärkraftskapaciteten. En ny förstärkningsmetod för trågbroar i betong har därmed föreslagits i och med denna avhandling, men en del frågetecken kvarstår och i kapitel 8 ges därför förslag på fortsatta forskningsområden.
Godkänd; 2013; 20130107 (jonnil); LICENTIATSEMINARIUM Ämne: Konstruktionsteknik/Structural Enginering Examinator: Professor Björn Täljsten, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Professor Mohammad Al-Emrani, Chalmers tekniska högskola, Göteborg Tid: Tisdag den 5 februari 2013 kl 13.00 Plats: F1031, Luleå tekniska universitet
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Carmichael, Benjamin Mark. "Fiber-reinforced polymer strengthening of War Memorial Bridge installation, load testing, and analysis /". Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Thesis/CARMICHAEL_BENJAMIN_2.pdf.
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Scheff, Jerry J. "Nondestructive testing of concrete bridge decks using ground penetrating radar and the chain drag method". Morgantown, W. Va. : [West Virginia University Libraries], 1998. http://etd.wvu.edu/templates/showETD.cfm?recnum=156.
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Thesis (M.S.)--West Virginia University, 1998.Title from document title page. Document formatted into pages; contains xv, 144 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 122-124).
22
Lopez, Ibaceta Alvaro Francisco. "Seismic Performance of Substandard Reinforced Concrete Bridge Columns under Subduction-Zone Ground Motions". PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4977.
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A large magnitude, long duration subduction earthquake is impending in the Pacific Northwest, which lies near the Cascadia Subduction Zone (CSZ). Great subduction zone earthquakes are the largest earthquakes in the world and are the sole source zones that can produce earthquakes greater than M8.5. Additionally, the increased duration of a CSZ earthquake may result in more structural damage than expected. Given such seismic hazard, the assessment of reinforced concrete substructures has become crucial in order to prioritize the bridges that may need to be retrofitted and to maintain the highway network operable after a major seismic event. Recent long duration subduction earthquakes occurred in Maule, Chile (Mw 8.8, 2010) and Tohoku, Japan (Mw 9.0, 2011) are a reminder of the importance of studying the effect of subduction ground motions on structural performance. For this purpose, the seismic performance of substandard circular reinforced concrete bridge columns was experimentally evaluated using shake table tests by comparing the column response from crustal and subduction ground motions. Three continuous reinforced columns and three lap-spliced columns were tested using records from 1989 Loma Prieta, 2010 Maule and 2011 Tohoku. The results of the large-scale experiments and numerical studies demonstrated that the increased duration of subduction ground motions affects the displacement capacity and can influence the failure mode of bridge columns. Furthermore, more damage was recorded under the subduction ground motions as compared to similar maximum deformations under the crustal ground motion. The larger number of plastic strain cycles imposed by subduction ground motions influence occurrence of reinforcement bar buckling at lower displacement compared to crustal ground motions. Moreover, based on the experimental and numerical results, subduction zone ground motion effects are considered to have a significant effect on the performance of bridge columns. Therefore, it is recommended to consider the effects of subduction zone earthquakes in the performance assessment of substandard bridges, or when choosing ground motions for nonlinear time-history analysis, especially in regions prone to subduction zone mega earthquakes. Finally, for substandard bridges not yet retrofitted or upgraded seismically, the following performance limit recommendation is proposed: for the damage state of collapse, which is related to the ODOT's Life Safety performance level, the maximum strain in the longitudinal reinforcement should be reduced from 0.09 (in./in.) to a value of 0.032 (in./in.) for locations where subduction zone earthquakes are expected, to take into consideration the occurrence of bar buckling.
23
Colombo, Alberto Belotti. "Applications of structural health monitoring and field testing techniques to probabilistic based life-cycle evaluation of reinforced concrete bridges". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-02122016-092514/.
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This work presents methodologies for the integration of field testing and Structural Health Monitoring SHM in the assessment of reinforced concrete bridges. The methodologies are demonstrated through the use of data collected during the testing of reinforced concrete railway bridges and long-term monitoring of a highway bridge. A probabilistic life-cycle prediction model based on sectional analysis is proposed for reinforced concrete structures. The updating of the model parameters is done using a Bayesian updating approach in which the problem is defined as a reliability one. An algorithm that uses subset simulation is used to sample points from the updated parameter distributions. Testing data from a reinforced concrete railway bridge is used to demonstrate the methodology and its results. The description of a SHM system that was installed in the Jaguari River Bridge is also presented. During the stages of preparation for the installation of this system the bridge was inspected, had NDT performed, and field testing was conducted using a test truck. The results of these tests are also presented. Analysis of the collected data from the live-load response of the Jaguari River Bridge is used to demonstrate methodologies for obtaining live-load response distributions from monitoring data. The use of this live-load response data is also used for the life-cycle analysis of one of the bridge\'s cross-sections.Este trabalho apresenta metodologias de integração de ensaios estruturais e Structural Health Monitoring (SHM) para a avaliação de pontes de concreto armado. O SHM diz respeito a um conjunto de praticas com o objetivo de acompanhar o comportamento estrutural através de sensores com o objetivo de acompanhar o comportamento da estrutura e determinar ações de manutenção de maneira proativa. As metodologias são apresentadas através do uso de dados coletados durante ensaios de pontes ferroviárias em concreto armado e do monitoramento continuo de uma ponte rodoviária. Um modelo para o ciclo de vida de estruturas de concreto armado baseado no método das lamelas é proposto. Os parâmetros deste modelo, que são considerados de maneira probabilística, são atualizados através de um método Bayesiano. Dados de ensaios de uma ponte ferroviária são utilizados nesta analise. A descrição de um sistema de monitoramento contínuo instalado na Ponte do Rio Jaguari também é feita. Durante as etapas de desenvolvimento do sistema a ponte foi inspecionada, ensaios não destrutivos foram feitos e ensaios com um veículo teste foram conduzidos. Os resultados e analises destes também são apresentados. Os dados coletados por este sistema foram utilizados para demonstrar metodologias de caracterização dos modelos de resposta devido a cargas moveis. A utilização destes modelos na avaliação de confiabilidade ao longo do tempo de uma das seções da ponte também é apresentada.
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Bosworth, Kyle Judson. "Health Monitoring of the Veterans' Glass City Skyway: Vibrating Wire Strain Gage Testing, Study of Temperature Gradients and a Baseline Truck Test". Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1197693985.
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Thesis (M.S.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science in Civil Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 86-87.
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Crane, Charles Kennan. "Shear and shear friction of ultra-high performance concrete bridge girders". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34745.
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Ultra-High Performance Concrete (UHPC) is a new class of concrete characterized by no coarse aggregate, steel fiber reinforcement, low w/c, low permeability, compressive strength exceeding 29,000 psi (200 MPa), tensile strength ranging from 1,200 to 2,500 psi (8 to 17 MPa), and very high toughness. These properties make prestressed precast UHPC bridge girders a very attractive replacement material for steel bridge girders, particularly when site demands require a comparable beam depth to steel and a 100+ year life span is desired.
In order to efficiently utilize UHPC in bridge construction, it is necessary to create new design recommendations for its use. The interface between precast UHPC girder and cast-in-place concrete decks must be characterized in order to safely use composite design methods with this new material.
Due to the lack of reinforcing bars, all shear forces in UHPC girders have to be carried by the concrete and steel fibers. Current U.S. codes do not consider fiber reinforcement in calculating shear capacity. Fiber contribution must be accurately accounted for in shear equations in order to use UHPC.
Casting of UHPC may cause fibers to orient in the direction of casting. If fibers are preferentially oriented, physical properties of the concrete may also become anisotropic, which must be considered in design.
The current research provides new understanding of shear and shear friction phenomena in UHPC including:
*Current AASHTO codes provide a non-conservative estimate of interface shear performance of smooth UHPC interfaces with and without interface steel.
*Fluted interfaces can be created by impressing formliners into the surface of plastic UHPC. AASHTO and ACI codes for roughened interfaces are conservative for design of fluted UHPC interfaces.
*A new equation for the calculation of shear capacity of UHPC girders is presented which takes into account the contribution of steel fiber reinforcement.
*Fibers are shown to preferentially align in the direction of casting, which significantly affects compressive behavior of the UHPC.
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Sheats, Matthew Reed. "Rehabilitation of reinforced concrete pier caps using carbon fiber reinforced composites". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19490.
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EDER, ERIC WILLIAM. "BEHAVIOR OF 50 YEAR OLD PRESTRESSED CONCRETE BRIDGE WITH FIBER REINFORCED POLYMER DECK REPLACEMENT". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060953606.
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KANTHA, SAMY MADHAN KUMAR. "FIELD TEST AND ANALYSIS OF TWO PRESTRESSED CONCRETE BRIDGES AFTER DECK REPLACEMENT WITH FRP PANELS". University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1187271654.
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El-Gharib, Georges. "Evaluation of the Empirical Deck Design for Vehicular Bridges". UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/489.
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This research evaluated the feasibility of the empirical design method for reinforced concrete bridge decks for the Florida Department of Transportation [FDOT]. There are currently three methods used for deck design: empirical method, traditional method and finite element method. This research investigated and compared the steel reinforcement ratios and the stress developed in the reinforcing steel for the three different methods of deck design. This study included analysis of 15 bridge models that met the FDOT standards. The main beams were designed and load rated using commercial software to obtain live load deflections. The bridges were checked to verify that they met the empirical method conditions based on the FDOT Structures Design Guidelines – January 2009. The reinforced concrete decks were designed using the traditional design method. Then the bridges were analyzed using three-dimensional linear finite element models with moving live loads. The reinforced concrete decks were designed using dead load moment, live load moment, and future wearing surface moment obtained from the finite element models. The required reinforcing steel ratio obtained from the finite element method was compared to the required reinforcing steel ratio obtained from traditional design method and the empirical design method. Based on the type of beams, deck thicknesses, method of analysis, and other assumptions used in this study, in most cases the required reinforcing steel obtained from the finite element design is closer to that obtained from the empirical design method than that obtained from the traditional design method. It is recommended that the reinforcing steel ratio obtained from the empirical design method be used with increased deck thicknesses to control cracking in the bridge decks interior bays.
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Bazáez, Gallardo Ramiro Andrés Gabriel. "Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted with Buckling-Restrained Braces". PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3476.
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Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level.
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Canfield, Scott Robinson. "Full Scale Testing of Prestressed, High Performance Concrete, Bridge Girders". Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7131.
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The objective of this research was to evaluate the current design specifications for use on prestressed, High Performance Concrete (HPC) bridge girders. An AASHTO Type IV and modified BT-56 girders were constructed with a 10,000 psi HPC to which a composite 7000 psi HPC deck was cast on top. The composite girders were tested in flexure, with the Type IV being tested to failure. The results of the flexure tests showed that the current AASHTO Specification for cracking moment and ultimate capacity are conservative.
In addition to flexural testing, each composite girder was studied with respect to the deck contraction induced girder deflection. Each deck and girder were instrumented with strain gauges and string potentiometes. The results of the study indicated the induced deflections are significantly greater than deflections from the deck dead load, and should be considered to accurately predict bridge deflection.
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Barrus, Natasha Christine. "Sensitivity of Resistivity Measurements on Concrete Bridge Decks to Operator-Controlled and Concrete Material Variables". BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3203.
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The objectives of this research were to investigate the sensitivity of two-prong and fourprong resistivity measurements to certain operator-controlled variables and to conduct a direct comparison of the sensitivity of two-prong and four-prong resistivity measurements to certain concrete material variables. Four full-factorial experiments were designed for this research. In the experimentation on operator-controlled variables with two-prong resistivity testing, main effects that are both statistically significant and practically important include hole depth and surface water. In the experimentation on operator-controlled variables with four-prong resistivity testing, probe position, surface water, and prong spacing are all neither statistically significant nor practically important. This high degree of unexplained variation may be of concern to practitioners. In the experimentation on concrete material variables with two-prong and four-prong resistivity testing, main effects that are both statistically significant and practically important include chloride concentration and temperature, both of which exhibit inverse relationships with resistivity. These research findings support several important recommendations for resistivity testing. Operators of the two-prong resistivity device should use an accurately positioned drill stop to ensure that the prepared holes are consistently the correct depth, and they should expect to obtain different values depending on the presence of surface water on the deck surface. Operators considering use of the four-prong resistivity device should not expect the measurements to be sensitive to probe position with respect to rebar, presence of surface water, or prong spacing for conditions similar to those investigated in this research. Operators interested in monitoring resistivity values over time to ascertain material changes in a bridge deck should develop protocols for measuring concrete temperature in the field and subsequently normalizing resistivity measurements to a standard temperature.
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Huffman, Jonathan M. "Destructive Testing of a Full-Scale 43 Year Old Adjacent Prestressed Concrete Box Beam Bridge: Middle and West Spans". Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1331319933.
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Eccles, Bradley James. "The use of non-linear vibrations in the health monitoring of reinforced concrete structures". Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323189.
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Chalishajar, Nirajkumar. "Condition assessment of concrete bridge girders using modal testing - a preliminary study". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67040.
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This thesis deals with vibration frequency evaluation using non-destructive modal testing of beam-type structures. The current state of Canada's bridges is reviewed for its present condition and urgent needs. The basic modes of deterioration in concrete bridges, namely, corrosion of reinforcing steel and freezing and thawing cycles were also reviewed. Bridge inspection fundamentals are discussed summarily. In addition, a summary of the available research on modal testing is presented. Five reinforced concrete beams were tested in this preliminary research program to study the effect of progressive cracking at increasing load levels on the changes in their natural frequencies. Analysis of the results shows that the natural frequency is related to the changes in the structural stiffness of the beam, and the level of damage. The results from this preliminary investigation show that vibration testing is a useful tool for studying the existing health of a structural system.L'auteur présente une étude préliminaire de la faisabilité d'utiliser des techniques d'analyse modale dans les poutres en béton armé comme méthode non-destructive d'évaluation de leur résistance.Un survol de l'état de détérioration des ponts au Canada permet d'abord d'établir les besoins les plus urgents. La thèse résume ensuite l'état des connaissances sur les modes de détérioration les plus communs dans les ponts en béton, soit la corrosion des aciers d'armature et les effets cycliques des conditions saisonnières de gel et dégel. Un résumé des étapes de base de l'inspection des ponts est également suivi d'une revue sommaire de la recherche sur les méthodes d'analyse modale.L'aspect expérimental de la recherche comprend des tests de mesures modales sur cinq spécimens de poutres en béton armé afin d'évaluer les variations de la fréquence naturelles des spécimens en fonction de leur état de fissuration induite par des surcharges. L'analyse des résultats indique clairement que la fréquence naturelle est réduite par les changements de rigidité des poutres selon le niveau d'endommagement. Les résultats de cette étude préliminaire indiquent que les méthodes vibrationnelles sont utiles pour évaluer la condition structurale des composants.
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Black, Rebecca Eileen. "Large-Scale Testing of Low-Strength Cellular Concrete for Skewed Bridge Abutments". BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7708.
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Low-strength cellular concrete is a type of controlled low-strength material (CLSM) which is increasingly being used for various modern construction applications. Benefits of the material include its ease of placement due to the ability of cellular concrete to self-level and self-compact. It is also extremely lightweight compared to traditional concrete, enabling the concrete to be used in fill applications as a compacted soil would customarily be used. Testing of this material is not extensive, especially in the form of large-scale tests. Additionally, effects of skew on passive force resistance help to understand performance of a material when it is used in an application where skew is present. Two passive force-deflection tests were conducted in the structures lab of Brigham Young University. A 4-ft x 4-ft x 12-ft framed box was built with a steel reaction frame on one end a 120-kip capacity actuator on the other. For the first test a non-skewed concrete block, referred to as the backwall, was placed in the test box in front of the actuator. For the second test a backwall with a 30° skew angle was used. To evaluate the large-scale test a grid was painted on the concrete surface and each point was surveyed before and after testing. The large-scale sample was compressed a distance of approximately three inches, providing a clear surface failure in the sample. The actuator provided data on the load applied, enabling the creation of the passive force-deflection curves. Several concrete cylinders were cast with the same material at the time of pouring for each test and tested periodically to observed strength increase.The cellular concrete for the 0° skew test had an average wet density of 29 pounds per cubic foot and a 28-day compressive strength of 120 pounds per square inch. The cellular concrete for the 30° skew test had an average wet density of 31 pounds per cubic foot and a 28-day compressive strength of 132 pounds per square inch. It was observed from the passive force deflection curves of the two tests that skew decreased the peak passive resistance by 29%, from 52.1 kips to 37 kips. Various methods were used to predict the peak passive resistance and compared with observed behavior to verify the validity of each method.
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Remund, Tyler Kirk. "Large-Scale Testing of Low-Strength Cellular Concrete for Skewed Bridge Abutments". BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/7213.
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Low-strength cellular concrete consists of a cement slurry that is aerated prior to placement. It remains a largely untested material with properties somewhere between those of soil, geofoam, and typical controlled low-strength material (CLSM). The benefits of using this material include its low density, ease of placement, and ability to self-compact. Although the basic laboratory properties of this material have been investigated, little information exists about the performance of this material in the field, much less the passive resistance behavior of this material in the field.In order to evaluate the use of cellular concrete as a backfill material behind bridge abutments, two large-scale tests were conducted. These tests sought to better understand the passive resistance, the movement required to reach this resistance, the failure mechanism, and skew effects for a cellular concrete backfill. The tests used a pile cap with a backwall face 5.5 ft (1.68 m) tall and 11 ft (3.35 m) wide. The backfill area had walls on either side running parallel to the sides of the pile cap to allow the material to fail in a 2D fashion. The cellular concrete backfill for the 30° skew test had an average wet density of 29.6 pcf (474 kg/m3) and a compressive strength of 57.6 psi (397 kPa). The backfill for the 0° skew test had an average wet density of 28.6 pcf (458 kg/m3) and a compressive strength of 50.9 psi (351 kPa). The pile cap was displaced into the backfill area until failure occurred. A total of two tests were conducted, one with a 30° skew wedge attached to the pile cap and one with no skew wedge attached.It was observed that the cellular concrete backfill mainly compressed under loading with no visible failure at the surface. The passive-force curves showed the material reaching an initial peak resistance after movement equal to 1.7-2.6% of the backwall height and then remaining near this strength or increasing in strength with any further deflection. No skew effects were observed; any difference between the two tests is most likely due to the difference in concrete placement and testing.
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Cope, M. D. "Experimental investigations and non-linear numerical analysis of skewed one-way prestressed concrete bridge decks". Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233798.
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Bolduc, Matthew W. "Full-Scale Testing of Pretensioned Concrete Girders with Partially Debonded Strands". University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613748086228573.
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SLACK, MICHAEL JAMES. "EXPERIMENTAL TESTING OF NON-EMBEDDED POSITIVE MOMENT CONNECTIONS". University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1022154276.
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Govindarajan, Balakumaran Soundar Sriram. "Corrosion Testing and Modeling of Chloride-Induced Corrosion Deterioration of Concrete Bridge Decks". Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26437.
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Modeling of chloride-induced deterioration of bridge decks by using Fickâ s Second Law of diffusion was performed. The objective of this study is to select suitable input parameters for the model to estimate the service life of bridge decks. Five bridge decks, one in each of the following states, Virginia, Florida, New Jersey, New York, and Minnesota were evaluated.
Data collection process involved visual inspections, damage surveys, corrosion testing including continuity, one-point resistivity, four-point resistivity, half-cell potentials, and three-electrode linear polarization, reinforcement cover depths, chloride samples. The Virginia bridge deck was built with epoxy-coated reinforcement as top reinforcement mat and black bar as the bottom mat. The Florida bridge is a segmental prestressed box girder structure built with black bar. The New Jersey bridge deck was overlaid with latex modified concrete. The New York bridge deck, which was built in 1990, is six inch concrete topping over prestressed adjacent box beams structure with epoxy-coated bar in the negative moment area. The Minnesota bridge was rebuilt in 1984. The deck was rebuilt with epoxy coated reinforcing steel in the top and bottom mats.
The probabilistic Fickian model requires reinforcement cover depths, surface chloride concentration, chloride initiation concentration, and diffusion coefficients as input parameters. The chloride initiation concentration was input via parametric bootstrapping, while the other parameters were input as simple bootstrapping. Chloride initiation concentration was determined from the chloride concentration at the reinforcement bar depths.
The modeling results showed that the deterioration of the Virginia bridge deck was corrosion controlled and the bridge will undergo increasingly severe damage in the future. Florida bridge deck is not undergoing corrosion and will not experience corrosion damage within 100 years. New Jersey bridge deckâ s service life has been most likely extended by the overlay. Deterioration of the New York bridge was not corrosion controlled, but was related to longitudinal cracking of the topping at match lines of adjacent box beams. Minnesota bridge deck is delaminated and contained a large number of cracks that should be included in service life modeling; otherwise the service life estimate is underestimated.
In addition to service life corrosion performance modeling, analyses were conducted on the relationships and interrelations of resistivity, corrosion potential, corrosion current and chloride at the reinforcing bar depth.Ph. D.
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Larsen, Jacob Lynn. "Automated Impact Response Sounding for Accelerated Concrete Bridge Deck Inspection". BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6989.
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Infrastructure deterioration is an international problem requiring significant attention. One particular manifestation of this deterioration is the occurrence of sub-surface cracking (delaminations) in reinforced concrete bridge decks. Of many techniques available for inspection, air-coupled impact-echo testing, or sounding, is a non-destructive evaluation technique to determine the presence and location of delaminations based upon the acoustic response of a bridge deck when struck by an impactor. In this work, two automated air-coupled impact echo sounding devices were designed and constructed. Each device included fast and repeatable impactors, moving platforms for traveling across a bridge deck, microphones for air-coupled sensing, distance measurement instruments for keeping track of impact locations, and signal processing modules. First, a single-channel automated sounding device was constructed, followed by a multi channel system that was designed and built from the findings of the single-channel apparatus. The multi channel device performed a delamination inspection in the same manner as the single-channel device but could complete an inspection of an entire traffic lane in one pass. Each device was tested on at least one concrete bridge deck and the delamination maps produced by the devices were compared with maps generated from a traditional chain-drag sounding inspection. The comparison between the two inspection approaches yielded high correlations for bridge deck delamination percentages. Testing with the two devices was more than seven and thirty times faster, respectively, than typical manual sounding procedures. This work demonstrates a technological advance in which sounding can be performed in a manner that makes complete bridge deck scanning for delaminations rapid, safe, and practical.
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Kalabon, Amy Elizabeth. "Implementation and Field Testing of Improved Bridge Parapet Designs". Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1399314661.
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Garas, Yanni Victor Youssef. "Multi-scale investigation of tensile creep of ultra-high performance concrete for bridge applications". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31689.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.Committee Co-Chair: Kimberly Kurtis; Committee Co-Chair: Lawrence Kahn; Committee Member: Arun Gokhale; Committee Member: James Lai; Committee Member: T. Russell Gentry. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Unruh, Richard Cornelius 1974. "The use of nondestructive testing methods for the condition assessment of concrete bridge girders". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29420.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (p. 68-72).
There are over 594,000 publicly controlled bridges in the United States. Concrete and pre-stressed concrete bridges account for nearly 50% of the bridges in the US inventory. This proportion is increasing each year, as new bridges tend to be constructed of concrete. This trend makes it vital for engineers to be able to accurately assess the condition of concrete for maintenance and repair decisions. The use of nondestructive testing methods can help reduce the backlog of deficient bridges in two ways. First, these techniques will allow inspectors to get a more accurate view of the condition of a bridge. The second way by which NDT can help is by allowing inspectors to locate damage earlier. This thesis is an attempt to capture the most current ideas for a very specific application of NDT: determining the condition of reinforced concrete bridges overall and bridge girders, in particular. To this end, attention is given to why NDT is needed and what aspects of concrete condition can be addressed with NDT. Some NDT methodologies that are, or may soon be, promising for concrete applications are discussed. Case studies are presented to demonstrate how NDT can be applied to concrete bridge girders and proposals are made for future areas of study and development.
by Richard Cornelius Unruh, III.
M.Eng.
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Bryant, James William Jr. "Non-Invasive Permeability Assessment of High-Performance Concrete Bridge Deck Mixtures". Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27241.
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Concrete construction methods and practices influence the final in-place quality of concrete. A low permeability concrete mixture does not alone ensure quality in-place concrete. If the concrete mixture is not transported, placed and cured properly, it may not exhibit the desired durability and mechanical properties.
This study investigates the in-place permeation properties of low permeability concrete bridge decks mixtures used in the Commonwealth of Virginia. Permeation properties were assessed in both the laboratory and in the field using 4-point Wenner array electrical resistivity, surface air flow (SAF), and chloride ion penetrability (ASTM C 1202-97).
Laboratory test specimens consisted of two concrete slabs having dimensions of 280 x 280 x 102-mm (11 x 11 x 4-in) and twelve 102 x 204-mm (4 x 8-in) cylinders per concrete mixture. Specimens were tested at 7, 28 and 91-days. Thirteen cylinder specimens per concrete mixture underwent standard curing in a saturated limewater bath. The simulated field-curing regimes used wet burlap and plastic sheeting for 3 (3B) and 7 days (7B) respectively and was applied to both slabs and cylinder specimens.
Slab specimen were tested on finished surface using the SAF at 28 and 91 days, and 4-point electrical resistivity measurements at 1, 3, 7, 14, 28 and 91 days. Compressive strength (CS) tests were conducted at 7 and 28 days. Chloride ion penetrability tests were performed at 7, 28, and 91 days.
Statistical analyses were performed to assess the significance of the relationships for the following: Total charge passed and initial current (ASTM C 1202-97); 3B resistivity and 7B resistivity; Slab and cylinder resistivity; Slab resistivity and ASTM C-1202-97 (Total Charge and Initial current); and Surface Air Flow and ASTM C-1202-97.
Field cast specimens, test slabs and cylinders, were cast on-site during concrete bridge deck construction. The slab dimensions were 30.5 x 40.6 x 10.2-cm (12 x 16 x 4 in.), and the cylinders were 10.2 x 20.4-cm (4 x 8-in). In-situ SAF and resistivity measurements were taken on the bridge deck at 14, 42 and 91 days. In-place SAF and resistivity measurements on laboratory field cast slabs were taken at 7, 14 and 28-days. ASTM C 1202-97 specimens were prepared from field cast cylinders and tested at 7 and 28 and 42-days. The relationship between in-place permeation measures from field specimens was compared to laboratory data.
Results indicated no difference in chloride ion penetrability (Figures 7.4 and 7.5) and 28-day compressive strength (Figure 7.2) with regard to differing simulated field curing regimes, for same age testing. There was no significant difference at the 95 % confidence level between 3B resistivity and 7B resistivity specimens tested at the same age (Figures 7.9 and 7.10).
A well defined relationship was observed between total charge passed and initial current (Figure 7-6). An inverse power function was found to describe the relationship between charge passed/initial current and electrical resistivity for all laboratory mixtures used in this study (Figure 7.17 â 7.22). Field data was used to validate laboratory established models for charge passed/initial current and electrical resistivity. Laboratory established models were able to predict 30 to 50% of the field data (Figures 7.31 â 7.34). Results indicate that the SAF lacked the sensitivity to classify the range of concretes used in this study (Figure 7.24).Ph. D.
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Setty, Clinton J. "Truck Testing and Load Rating of a Full-Scale 43-Year-Old Prestressed Concrete Adjacent Box Beam Bridge". Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1331318991.
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Marson, Julia Elizabeth. "Cyclic testing of concrete-filled circular steel tube bridge columns having encased fixed-based detail". Thesis, University of Ottawa (Canada), 2000. http://hdl.handle.net/10393/9331.
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Concrete-filled steel tube columns have been recognized to have many desirable characteristics that can lead to stable hysteretic energy dissipation during earthquakes. They also have many other properties that make them advantageous for bridge applications (i.e. steel tube provides confinement to the concrete and acts as formwork during construction; concrete enhances the local buckling resistance of the steel tube; construction can be accelerated when the tube alone can carry the dead-loads; no need for stain protection on piers when superstructure is of weathering steel; final aesthetic of the product compatible with current practice, etc.). A literature review was performed to collect data on the behaviour of concrete-filled steel tubes under axial load, combined axial and bending forces, and cyclic forces. Analytical work was performed to ensure that the test columns chosen would be representative of full-scale bridge piers found in North America. The foundation detail was designed to ensure that the full moment capacity of the composite column could be developed at its base without failure of the foundation. This study involved testing four concrete-filled steel tubes under a constant axial load and subjected to an increasing cyclic horizontal force applied at the top of the column. All four columns sustained drifts of 7% before failure occurred by the steel tube fracturing at the location of the local buckles. Subsequent analytical work lead to two new proposed design equations. These produce axial-flexure interaction equations in much better agreement with the existing data than the equations for circular concrete-filled steel tubes currently used by the Canadian CAN/CSA-S16.1-M94 standard, or American AISC LRFD 1994 Specifications.
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Marson, Julia. "Cyclic testing of concrete-filled circular steel tube bridge columns having encased fixed based detail". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/MQ57138.pdf.
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Hoki, Jeffrey Ryan. "Analysis of Selected Factors Affecting Concrete Cover Measurements on Bridge Decks". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2617.
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The objective of this research was to quantify the effects of selected parameters on the accuracy of concrete cover measurements on bridge decks. This research involved three full-factorial laboratory experiments each designed to investigate one of three primary variables. These primary variables included distance to a parallel adjacent bar, distance to a reinforcement intersection, and incorrect bar size input for the cover meter. Each experiment also involved four secondary variables known to affect cover readings. These secondary variables included actual cover depth, meter brand, antenna type, and bar size. Statistical analyses were performed to determine the significance of each factor. A margin of error of 0.125 in., corresponding to the increase in diameter between successive U.S. standard rebar sizes, was established as the threshold for practical importance in the data analysis. Three primary findings resulted from the three experiments performed in this research. For the meters and antennas tested, the results of the field-of-view experiment indicated that, if the spacing is greater than approximately 4.0 in., the returned readings are within the threshold for practical importance established for this research. The results of the proximity-to-an-intersection experiment indicated that, regardless of where the measurement is taking place in relation to an intersection, the operator can be confident that the errors will be less than 0.125 in. as long as the bar in question is above the intersecting bar. The results of the wrong-bar-size experiment indicated that, if the operator of the cover meter does not know the actual rebar size in question, the measured cover will be within 0.125 in. of the actual cover depth as long as the meter input is within one bar size of the correct value. Obtaining accurate cover measurements on bridge decks is important for quality assurance, service life prediction, and rehabilitation programming.