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1
Katwan, Moufaq Jassem. "Corrosion fatigue of reinforced concrete." Thesis, University of Glasgow, 1988. http://theses.gla.ac.uk/5327/.
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This work is concerned with the corrosion fatigue characteristics of full-scale reinforced concrete beams partially submerged in 3.5% NaCl solution or in tapwater of low dissolved salt content. The test beams were subjected to constant amplitude fatigue loading in uni-directional or reverse bending at slow cycle rate of 0.17 Hz and various load levels. The test programme had two stages: Stage I, carried out at relatively high load levels, represented a study of the fatigue-failure phenomenon but also provided guides for the more detailed study undertaken in Stage II which was devoted to low load conditions under which the main steel deterioration process was corrosion. In the latter stage, attention was focused on the monitoring of a number of electrochemical parameters including the corrosion rate. Late in the programme, electrochemical noise technique was also examined. The phenomenon of concrete crack blocking, previously reported in seawater environment, was observed in both test environments in this work. This phenomenon was closely examined and the mechanisms of the formation of deposits and its effects were described. A hypothesis was proposed for the structural behaviour of reinforced concrete beams during cyclic loading in aqueous environment. Failure normally occurred by the fracture of one of the main tensile bars due to fatigue, often followed immediately by yield of the remaining bar and beams collapse. Fracture surfaces were examined under SEM.Corrosion rate measurements involved formidable difficulties which had to be overcome to obtain accurate measurements. For instance, the current interruption technique for the estimation of the IR-drop was developed and established as the most appropriate method for concrete beams with complex reinforcement configuration. Extensive polarisation measurements indicated clear effect of the test condition on the technical variables involved in various measuring techniques (viz potentiodynamic and potentiostatic techniques). Based on these observations a criterion has been proposed to determine the appropriate variables necessary for the accurate determination of the polarisation resistance Rp. The work has demonstrated that the corrosion behaviour of reinforced concrete sustaining dynamic loading is extremely complex, and short term indications could not be used safely for long term predictions. Based on corrosion rate measurements and the actual corrosion pattern observed upon completion of the tests, a concept of a change in corrosion mechanism from a microcell process of relatively low corrosion rates to a macrocell process at much accelerated high rates is introduced. The prevailing mechanism depends on time of exposure, load level and reinforcement details. Results from long running fatigue tests in seawater from concurrent research were incorporated which also support this concept.
2
Gordon, Paul Mark. "Low Cycle Fatigue Behavior of Concrete with Recycled Concrete Aggregates." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/577.
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A comparison of concrete containing recycled concrete coarse aggregates and natural coarse aggregates subjected to high strain, low cycle compressive fatigue is presented. Using a strain based feedback control loop, concrete cylinders are compressed at 15µε/s to a specified strain then unloaded to zero stress for 10 cycles. After cycling, all samples are loaded to a strain of 0.008. Direct concrete material variables are the water to cement (w/c) ratio, taken as 0.60, 0.45, and 0.39, and percent coarse recycled concrete aggregate content, varied from zero to 100 percent. The primary testing variable is the specified unloading strain. Unloading strains include 60, 75, 90, 100, and 120 percent of the strain at peak stress. Ten batches of concrete were made, generating a total of 224 samples for testing. Findings confirm previous research showing a reduction in strength with increasing recycled concrete coarse aggregate content, an equivalent concrete with only 25 percent replacement of natural coarse aggregates and an equivalent strength concrete with a decrease in the w/c ratio and 100 percent recycled concrete coarse aggregates. Fatigue testing indicates that each cycle’s maximum stress remains unchanged, but the stiffness degrades more rapidly with increasing recycled aggregate content and a constant w/c ratio.
3
Foo, M. H. "Behaviour of partially prestressed concrete structures under fatigue loading /." Title page, table of contents and abstract only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phf686.pdf.
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Vetsa, Appalaraju. "Performance of doweled concrete joints subjected to fatigue loading." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3059.
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Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains xi, 114 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 102-105).
5
Luheshi, Yousef Bashir. "The fatigue characteristics of precast concrete raft units." Thesis, University of Newcastle Upon Tyne, 1997. http://hdl.handle.net/10443/1582.
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This research project represents a continuation of the research programme into Precast Concrete Pavement Units, "P. C. P. U. ", which is based in the Department of Civil Engineering at the University of Newcastle upon Tyne. The units were referred to as raft units throughout the thesis which focused on the use of raft units as a full concrete paving system for aircraft parking, taxiway, and other low speed areas, at airports. The physical full scale test model was designed and constructed to represent the applied loading from one of the dual wheel legs of the design aircraft, a Boeing 727-200, when it is taxiing over a raft unit paving system. It was only possible for the test model to be provided with a contact area of 200 mm square compared to the real life of 400 mm square. A theoretical correction was applied to allow for this difference. Sixteen raft units were tested in pairs using the test model. The tests were divided into three modules to investigate the effect of the raft unit dimensions, Module(M1); the reinforcement design, Module(M2); and the raft thickness, Module(M3). The twin loading assembly applied a repetitive dynamic load which was moved manually between four different loading positions to represent the aircraft moving across the raft units. The primary aim of the experimental programme was to identify for the first time the fatigue life and failure mechanisms of the raft units under the influence of twin dynamic moving loads, and provide experimental results to enable a more refined numerical design method to emerge for raft units, as well as to determine the causes of failures and to recommend remedial measures. Observations were made of vertical deflection, concrete strains, crack widths and crack patterns, failure load, and failure modes, each of which were described in detail. The test observations showed that by increasing each of the following variables, namely, the aspect ratio, the amount of steel bar reinforcement and the thickness of the raft units, resulted in each case in an extension of raft unit life. It was found that some form of uplift restraint on the raft unit should be added to improve the fatigue life for one of the loading positions and that fibre reinforcement should not be used. The ultimate load capacity of the raft units was influenced by the loading position, the applied load level and the number of load repetitions, together with the crack patterns. Using the results from the raft units that had failed within a specific module, it was possible to predict the ultimate and reserve load capacity of raft units within the modules that were only partially fatigued. Four important conclusions have been established during the research project. Firstly, based on the test results, an empirical relationship was derived using regression analysis, relating the number of load repetitions to the aspect ratio, the amount of reinforcement, the raft thickness, and the applied loading. This will need further verification, but it should eventually be very useful when estimating the fatigue life of these specific raft unit models. Secondly, a new design method has been proposed. The design methods for raft units proposed previously by Bull, Ismail, Annang, Ackroyd, and the British Port Association were reviewed. The test results enabled a new design method to be developed which was based on Bull's method but proposed new design charts and tables for each of the raft units considered in the research project which introduced the additional variables of contact pressure and the exact loading position. Thirdly, the measured strains were used to develop strain fatigue relationships for designing raft units and estimating the reserve design life in a raft unit paving system for the purpose of maintenance management by relating the accumulated number of load repetitions of a design load to the permissible concrete strain. The strain fatigue equations were generated for each of the raft units considered in this research project. Thus, the most realistic way to control raft unit distress is through the use of a predictive fatigue model. This should prove invaluable to those involved in the maintenance of raft unit paving systems. Finally, life cycle cost analysis was conducted for three types of construction pavement (paving blocks, PQC, and raft units). The analysis demonstrated that the precast concrete raft units will become a viable alternative to conventional pavement construction and a real competitive to the concrete paving blocks.
6
James, Valontino Ruwhellon. "Fatigue Behaviour of CFRP Strengthened Reinforced Concrete Beams." Master's thesis, Faculty of Engineering and the Built Environment, 2020. http://hdl.handle.net/11427/32274.
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The performance of reinforced concrete (RC) structures, such as bridges in the heavy haul industry, may be severely impacted by fatigue when subjected to repeated cyclic loading. Fatigue not only reduces load carrying capacity and serviceability limit states (SLS), but it can cause structural failure even when the components are subjected to low stress range cyclic loading. Corrosion damage exacerbates fatigue related problems as chloride induced pitting corrosion facilitates the formation and gradual propagation of cracks under cyclic loading. A common rehabilitation and retrofitting approach that involves patch repairing and fibre reinforced polymer (FRP) strengthening has proven effective to not only restore structural capacity, but also to enhance infrastructure service life. The structural repair process involves the replacement of deteriorated cover concrete with a less permeable patch repair mortar. The patch repair only restores durability of the structure; to restore or enhance structural capacity the repair process further involves bonding of FRP laminates. Particularly in the case of FRP's with a low elastic modulus, the design is often guided by serviceability limit states as opposed to ultimate limit states (ULS), resulting in an over-reinforced structural member. In addition, the reinforcement area of commercially available FRP strengthening may exceed the design requirements, especially at low levels of corrosion damage. In both the abovementioned considerations the design may result in an over-reinforced section. At the time when this researched was proposed, the effect of increasing damage extent on fatigue behaviour of over-reinforced RC beams was not clear and merited further investigation. A scientific experimental approach was developed to investigate the long-term performance of fifteen (15) full-scale 40MPa RC beams with dimensions 155x254x2000mm and ultimate capacity of 62.3kNm. Accelerated corrosion damage was induced in varied extents which included 450mm, 800mm, 1300mm and 1800mm length to a constant degree of 10% on all specimens. Specimens from each damage extent were patch repaired using SikaCrete214 and subsequently strengthened with externally bonded with SikaCarboDurS512 carbon fibre reinforced polymer (CFRP) laminates. Four-point bending monotonic loading tests were conducted on one (1) specimen from each damage extent. The results obtained from the quasi-static tests were used to determine two (2) cyclic loading stress ranges at which the remaining 2 specimens from each damage extent would be tested under. Under the 40% and 60% stress ranges four-point bending cyclic loading tests were carried out at a test frequency of 4Hz. Information was acquired on key performance indicators that included fatigue life, crack development, failure mode and stiffness degradation, where stiffness was assessed in terms of midspan deflection, composite material strains and neutral axis shift. Information on these parameters were collected using strain gauges, linear variable differential transducers (LVDT), DEMEC strain targets and digital image correlation (DIC). Ultimate failure loads under monotonic loading showed that despite having the highest degree of corrosion, the 450mm damage extent specimen had the highest failure load of 325kN. The failure load gradually reduced to 290kN as the damage extent was increased to 1800mm and the 0mm (control) specimen failed at the lowest load of 274kN. In contrast to the static behaviour, the specimen fatigue life enhanced by 106.3% as the damage extent was increased from 450mm to 1800mm. As expected, the 40% stress range tests yielded much longer fatigue lives than their 60% stress range counterparts. Furthermore, the experimentally obtained fatigue lives were compared to three fatigue life prediction models and the Helgason and Hanson model yielded the closest correlation with the experimental results. IV ABSTRACT Crack densities were found to increase with a longer fatigue life. An increase in damage extent was found to positively affect crack development and overall stiffness of the specimen during longterm fatigue testing. This finding was further substantiated by an assessment of midspan deflection, compression concrete strain and carbon fibre strain results, which all suggested a lower neutral axis and a lower stiffness reduction rate under fatigue loading as the damage extent was increased from 450mm to 1800mm. Furthermore, the tension concrete cracks propagated gradually during longer fatigue tests periods, while the tension steel and carbon fibre were comparably less affected by the resultant internal forces. Unfortunately, the neutral axis strain measurements using DEMEC targets were unable to assess the relative effect of an increase in damage extent as well as the compression concrete and carbon fibre strains were able to. During this experimental period, it was established that the laboratory layout was not conducive for carrying out the DIC process of long-term cyclic loading tests. The area in which testing took place did not adequately protect the camera against the environment and therefore required daily storage of the equipment. Regular movement of the camera for storage purposes introduced measurement inaccuracies which accumulated over longer test periods of up 20 days. However, for the short-term tests that did not require movement of the camera, the DIC process yielded favourable results. It was possible to capture the crack patterns early in the test period when the crack growth rate and development of new cracks was high using DIC. It was found that the high strain cracks coincided with the points of maximum vertical deflection (obtained through DIC) and eventual failure location of the specimen. The points of maximum deflection obtained from the DIC process were often not at midspan, which in the absence of the DIC process, would not have been possible to predict accurately. The results have shown that the specimens with the longer damage extents exhibit improved fatigue performance than their shorter counterparts. This revealed a stark contrast to their monotonic loading performance which favoured shorter damage extents. Furthermore, DIC holds potential to predict failure location more accurately than conventional approaches used for structural health monitoring (SHS).
7
Dung, Pham-Thanh. "Strengthening of concrete bridges using reinforced sprayed concrete under state and fatigue loading." Thesis, Queen Mary, University of London, 1997. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1575.
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The Department of Transport's bridge assessment programme has revealed that a significant number of bridges are not strong enough to carry the much heavier commercial axle loads that will soon be applied to UK bridges. To address this problem, this research investigates a technique of strengthening concrete bridges by bonding and encapsulating an extra layer of reinforcement using sprayed concrete to the soffit of the bridge to increase the flexural capacity. An experimental investigation on approximately one eighth scale reinforced concrete slabs strengthened by different amounts of reinforcement placed at varying depths below the soffit and encapsulated by professionally applied dry-mix sprayed concrete, have shown that increased flexural capacity of up to eight times the original capacity is possible with no sign of breakdown of the bond at the soffit interface. Separate interface shear tests both direct and indirect were carried out and showed high shear capacities were obtained in all specimens. The susceptibility to weathering causing a breakdown of the interface bond was investigated by freeze-thaw tests. Fatigue load tests have also shown that the strengthened slabs have a similar life span to that of normal reinforced concrete. An analytical study was carried out, complemented by the fatigue load test results, to assess the life span of two highway bridges when subjected to fluctuating traffic loading, taking into account the proposed increasing use of heavier axle loads. All the slabs tested to failure under both static and fatigue loading failed in flexure and extremely good bond between the sprayed concrete layer and its substrate concrete was maintained right up to failure, even without shear connectors. The potential use of this technique in practice was therefore well demonstrated.
8
Al-Azzawi, Bakr. "Fatigue of reinforced concrete beams retrofitted with ultra-high performance fibre- reinforced concrete." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/108101/.
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Concrete structures deteriorate over time due to different reasons and thus may not perform their function satisfactorily. Repair and rehabilitation of deteriorated concrete structures is often preferred over demolition and rebuilding for economic reasons. Various metallic and nonmetallic materials have been used in the past for repair and rehabilitation. These materials have advantages and disadvantages. The latter are connected with the mismatch in the properties of these materials with the material of the structure being repaired which often resulted in unwanted failure modes, e.g. delamination. For this reason, new cement-based ultra-high performance reinforced with steel fibres repair materials have been developed in the last two decades, which restore (and even enhance) the structural response and improve the durability of repaired concrete structures. One such ultra-high-performance fibre-reinforced concrete material is CARDIFRC. It is characterized by very high compressive strength, high tensile /flexural strength, and high energy-absorption capacity. However, it is very expensive and thus industrially uncompetitive due to the very high cost of thin brass-coated steel fibres used in it. It is therefore important to develop a version of CARDIFRC that is industrially competitive. This is one of the objectives of this research. An ultra-high-performance fibre-reinforced concrete (UHPFRC) has been developed that is far less expensive than CARDIFRC and at the same time self-compacting. The steps necessary to achieve this have been described in this work. In addition, a full mechanical and fracture characterisation (i.e. size-independent fracture energy and the corresponding bi-linear stress-crack opening relationship) of this UHPFRC is presented. A nonlinear cracked hinge model has been used to back calculate the stress-crack opening relation of this material in an inverse manner from the test data. The second objective of this research concerns the flexural fatigue behaviour of this new UHPFRC. Tests have been conducted under several stress amplitude ranges. It has been found that the distribution of fibres plays a vital role in its fatigue resistance. Regions with few or no fibres can drastically reduce its fatigue life. As expected, non-zero mean stress leads to a significant reduction in the fatigue life of a material compared to cyclic loading with zero mean. The variation in compliance during cyclic loading has been used to estimate the expected fatigue life under a given cyclic load range, since the tests were terminated at one million cycles. The third objective of this research concerns the flexural fatigue behaviour of RC beams retrofitted with precast strips of this self-compacting UHPFRC on the tension face. Fatigue tests under several stress amplitude ranges have shown that this UHPFRC is an excellent retrofit material under fatigue loading. Again, the variation in compliance during the fatigue loading has been used to estimate the expected fatigue life for retrofitted RC beams.
9
Lee, Hon. "Fatigue behavior of concrete beams prestressed with glass fiber reinforced plastic (GFRP) tendon /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20LEE.
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Yacoub, Mohamad Toufic 1957. "PERFORMANCE CRITERIA FOR REINFORCED CONCRETE BEAM-COLUMN CONNECTIONS." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275564.
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Seracino, R. "Partial-interaction behaviour of composite steel-concrete bridge beams subjected to fatigue loading /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phs481.pdf.
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Karimnassaee, Ali 1959. "FLEXURAL BEHAVIOR OF LIGHTLY REINFORCED UNBONDED POST-TENSIONED CONCRETE BEAMS." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275510.
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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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Montazeri, Sara. "Assessing repeatability of four-point bending method for estimating fatigue cracking of hot mix asphalt." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Walubita, Lubinda F. "Comparison of fatigue analysis approaches for predicting fatigue lives of hot-mix asphalt concrete (HMAC) mixtures." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/3898.
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Hot-mix asphalt concrete (HMAC) mixture fatigue characterization constitutes a fundamental component of HMAC pavement structural design and analysis to ensure adequate field fatigue performance. HMAC is a heterogeneous complex composite material of air, binder, and aggregate that behaves in a non-linear elasto-viscoplastic manner, exhibits anisotropic behavior, ages with time, and heals during traffic loading rest periods and changing environmental conditions. Comprehensive HMAC mixture fatigue analysis approaches that take into account this complex nature of HMAC are thus needed to ensure adequate field fatigue performance. In this study, four fatigue analysis approaches; the mechanistic empirical (ME), the calibrated mechanistic with (CMSE) and without (CM) surface energy measurements, and the proposed NCHRP 1-37A 2002 Pavement Design Guide (MEPDG) were comparatively evaluated and utilized to characterize the fatigue resistance of two Texas HMAC mixtures in the laboratory, including investigating the effects of binder oxidative aging. Although the results were comparable, the CMSE/CM approaches exhibited greater flexibility and potential to discretely account for most of the fundamental material properties (including fracture, aging, healing, visco-elasticity, and anisotropy) that affect HMAC pavement fatigue performance. Compared to the other approaches, which are mechanistic-empirically based, the CMSE/CM approaches are based on the fundamental concepts of continuum micromechanics and energy theory.
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Heffernan, P. J. "Fatigue behaviour of reinforced concrete beams strengthened with CFRP laminates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22787.pdf.
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Johansson, Ulrika. "Fatigue tests and analysis of reinforced concrete bridge deck models /." Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1820.
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MEDEIROS, ARTHUR. "STUDY OF THE COMPRESSIVE FATIGUE BEHAVIOR OF FIBER REINFORCED CONCRETE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34905@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Esta pesquisa teórico-experimental teve como objetivo avaliar a influência da frequência de carregamento no comportamento à fadiga em compressão do concreto com e sem fibras e foi realizada através da colaboração entre a Pontifícia Universidade Católica do Rio de Janeiro e a Universidad de Castilla-La Mancha – Espanha durante o doutorado sanduíche. A motivação surgiu da idéia de construir torres eólicas, com cem metros de altura, em concreto de alto desempenho como uma solução mais econômica. Estas torres estão submetidas a ciclos de carga e descarga com frequências desde 0,01 Hz até 0,3 Hz. A adição de fibras melhora o desempenho do concreto à tração, reduzindo a fissuração. No estudo experimental foram produzidos três concretos de mesma matriz: sem fibras, com fibras de polipropileno e fibras de aço. Foram realizados 124 ensaios de fadiga em compressão em corpos de prova cúbicos de 100 mm de aresta, divididos em doze séries: três concretos e quatro frequências 4 Hz, 1 Hz, 0,25 Hz e 0,0625 Hz. Comparando-se o número de ciclos até a ruptura foi possível verificar experimentalmente que a frequência influenciou o comportamento do concreto à fadiga em compressão e que a adição de fibras melhorou o desempenho à fadiga apenas para as frequências mais baixas. O desempenho das fibras de aço foi bastante superior ao das de polipropileno. Foi proposto um modelo probabilístico que busca relacionar os parâmetros de um ensaio de fadiga com a frequência de carregamento, levando em consideração a distribuição estatística dos ensaios de fadiga e das propriedades mecânicas do concreto. O modelo foi validado pelos resultados experimentais. Foi comprovado que a ruptura é probabilística em termos do número de ciclos N ou da taxa de deformação específica secundária, e que existe uma relação direta entre N e. Em termos práticos, o modelo permite estimar o número de ciclos até a ruptura sem chegar a romper o corpo de prova.
This work presents the results of a theorical-experimental study performed in cooperation between the Pontifícia Universidade Católica do Rio de Janeiro and the Universidad de Castilla-La Mancha in Spain. The main goal was to verify the influence of the loading frequency on the compressive fatigue behavior of plain and fiber reinforced concrete FRC. The motivation comes from the intention on building wind energy generator towers with one hundred meters in height by using a high-performance concrete as a cheaper alternative material instead of steel. These towers are subjected to load and unload cycles at frequencies from 0,01 Hz to 0,3 Hz. The addition of fibers improves concrete properties such as tensile strength, reducing cracking. In the experimental study three types of concrete were produced from the same matrix: a plain concrete and two FRC, with polypropylene fibers and with steel fibers. One hundred twenty four compressive fatigue tests were performed on cubic specimens with 100 mm in edge length, divided on twelve series: three types of concrete and four frequencies 4 Hz, 1 Hz, 0,25 Hz and 0,0625 Hz. Comparing the number of cycles to failure, it is clear that the loading frequency influences the compressive fatigue behavior and that the addition of fibers improves fatigue performance only at the lower frequencies. The performance of the steel fibers is more efficient than the polypropylene ones. A probabilistic model was proposed to relate the fatigue parameters with the loading frequency, considering both statistical distributions of the fatigue tests and the concrete mechanical properties. There is a good agreement between the model and the experimental results. In terms of number of cycles N or strain history (through the secondary strain rate) the rupture is probabilistic, and there is a direct relation between N and. This relation provides the possibility to estimate the number of cycles to failure without breaking the specimen.
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ADRESI, MOSTAFA. "Concrete pavement prediction life model based on electrical response of concrete-CNTs sensors under fatigue loading." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2687875.
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Structural Health Monitoring (SHM) of important infrastructures such as Portland cement concrete pavements plays a key role in pioneer societies, to guarantee the optimum usability and performance of the infrastructure system. As an example, this is imperative to appraise the destruction level in Portland cement concrete pavements along time as to plan their maintenance with proper actions at the right time. Based on this premise, the goal of this study is to extend an extensive feasibility study to set up a novel approach for SHM of Portland cement concrete pavements and remaining life estimation, based on self-sensing concrete-CNTs sensors added with multi-walled carbon nanotubes (CNTs). The concrete-CNTs sensors are applied as piezoresistive sensors (i.e. to collect information such as weight and species of passing vehicles), or as destruction identification sensors (i.e. to detect crack propagation in the Portland cement concrete pavement). For casting the concrete-CNTs sensors, some parameters are important, such as the number of CNTs, species of surfactant, dispersion quality etc. In this research, the dispersion quality of multi-walled carbon nanotubes in the aqueous phase and cement matrix was experiment examined using Ultraviolet-Visible Spectrophotometry (UV-VIS), Scanning Electron Microscopy (SEM) and mechanical experiments for compressive and flexural strength. The outcomes demonstrated that a new specific surfactant composition (sodiumdodecylbenzene sulfonate (SDS) and superplasticizer carboxylate base (SP-C) with the ratio of 1:9 respectively) could disperse MWCNTs around 64% more than other surfactant combinations indicated in the previous studies while this has enough compatibility with the concrete to omit antifoam in the mixing process and maintain the concrete mechanical specifications pretty constant. To appraise the influences of the main parameters affecting concrete-CNTs sensors function, diverse criteria in static and dynamic loading patterns were defined such as sensitivity of the sensor (Se), the standard deviation of the prediction error, repeatability (Re), cross-correlation (CC) and hysteresis (SSE). The dynamic criteria such as sensitivity, internal repeatability, cross-correlation and hysteresis declared that the dispersion energy levels for the dispersion of MWCNTs have a major impact on enhancing the function of the sensor rather than the number of CNTs. The repeatability criterion, contrariwise, showed that the number of MWCNTs has a major impact on the function of the sensor compared to the dispersion quality (dispersion energy level) of MWCNTs. Consequently, both parameters have to be regarded as relevant. The overall outcomes showed that the sensors fabricated with 0.15 wt% CNTs, superplasticizer and SDS as a surfactant using the maximum dispersion energy level (ultrasonic bath for 2 hours and 90 minutes of ultrasonic probing) have the best function in both static and dynamic load mode. To explore the influences of traffic loads on the pavement, concrete-CNTs sensors were experiment examined under various value of dynamic loads. The outcomes demonstrated that the maximum exterior load applied on the sensor (Fmax) is linearly correlated to the maximum response of the sensor (Smax) via a constant coefficient tagα/tagβ, in which tagα is defined as the slope of the Force vs. Time graph and tagβ is defined as the slope of the Sensor’s response vs. Time curve. So, this can be concluded that the application of the indicated concrete-CNTs sensors for piezoresistive applications is feasible and the sensors can appraise the load with of high-goodness of fit (R2adj.> 0.99). In addition, to study the response of the concrete-CNTs sensor under the traffic loading, fatigue experiments were run. An alternative data processing log(G)-log(N) was applied instead of traditional S-log(N) fatigue graphs (Goodman curves), based on the electrical sensor response with a linear regression approach and the outcomes were verified by statistical tests. In this research, the concept of G has been defined for the first time as the slope of a sensor’s response that reflects the destruction created in a pavement because of one pass of vehicle load. Based on these findings, two various types of remaining life models for Portland cement concrete pavements were proposed.
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DeYoung, Kenneth Lee. "Flexure shear response in fatigue of fiber reinforced concrete beams with FRP tensile reinforcement." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4894.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 24, 2008) Includes bibliographical references.
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Peters, Timothy M. "Ultimate failure criteria for prestressed concrete T-beams." Thesis, Queensland University of Technology, 1989. https://eprints.qut.edu.au/36455/1/36455_Peters_1989.pdf.
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The adoption of a limit states design approach for concrete
design requires a realistic assessment of the flexural
capacity of reinforced, prestressed, and partially
prestressed concrete structures at their ultimate limit
state.
The author has investigated experimentally the post-elastic
behaviour of a series of continuous partially prestressed
concrete T-beams and draws comparison to tests on similar
beams of rectangular section.
Use of photogrammetric measuring techniques to produce
moment curvature relationships was made during the testing
process.
Results have shown that partially prestressed concrete
beams of Tee section can possess sufficient rotation
capacity to allow full redistribution of bending moments.
The rotation capacity was shown to increase as the
reinforcing index of a section decreased. A similar
relationship was found with the prestress ratio.
Softening of the section prior to failure was also observed
at the initial plastic hinge. It was also found that
torsional moments can have a significant effect on the in
plane moment-curvature relationship of a section.
22
Rogers, Angela D. "Shear fatigue of concrete highway joint sealants in un-dowelled pavements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0006/MQ35523.pdf.
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Goodhead, Andrew H. "The static and fatigue behavior of low profile precast concrete sleepers." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31512.
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Low Profile precast concrete sleepers have the same vertical dimension as traditional wooden sleepers and thus offer a promising alternative to replace wooden sleepers on tracks where maintaining vertical alignment is necessary. The structural response of Low Profile precast concrete sleepers was studied under static and fatigue loading regimes using a tuned finite element model and four point flexure laboratory tests. The fatigue tests were conducted by following the procedure specified in the Australian railway code (AS 1084.14-2012). The usefulness of the Australian code fatigue test was brought into question as the fatigue life of Low Profile sleepers far exceeded the 3 million load cycle specified by the code. This study concluded that Low Profile concrete sleepers have excessive fatigue resistance however the limiting design criteria for Low Profile sleepers should be governed by a serviceability approach in order to limit cracking and thus ensure an adequate durability life span.
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Baroni, Henriette Justina Manfredini. "Simulação da vida útil de fadiga do concreto em vigas de tabuleiro de pontes em função do fluxo de veículos pesados." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26005.
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A fadiga é um processo de degradação importante, que pode se manifestar de maneira intensa em estruturas sujeitas à ação de carregamentos cíclicos, tais como as pontes rodoviárias. A fadiga consiste num mecanismo de acumulação de micro-danos, que envolve a formação e o crescimento de fissuras, e que pode, depois de um determinado número de ciclos, culminar na completa fratura do material sob ação de tensões bem inferiores à sua tensão última de ruptura. No caso de pontes rodoviárias, o procedimento de cálculo visa assegurar que as tensões de trabalho nos materiais sejam pequenas, muito inferiores às tensões de ruptura, de maneira que os micro-danos sejam quase inexistentes, tornando necessário um elevadíssimo número de ciclos para provocar a fadiga. Normalmente, em projeto é considerado o efeito, em termos de tensões, da passagem do trem tipo, carregamento padrão recomendado pelas Normas Brasileiras, sobre a estrutura. Na vida real, todavia, cada veículo resulta em uma ação diferenciada sobre a estrutura, dependendo de seu peso total e da distribuição do mesmo no rodado. Fica evidente que os veículos pesados são aqueles que consomem mais rapidamente a vida útil de fadiga, pois os mesmos podem resultar em grandes diferenciais de tensão, principalmente em estruturas onde o peso próprio é relativamente pequeno. Diante da tendência de aumento do volume de tráfego e do incremento no peso total dos veículos circundantes, torna-se preocupante a situação para as pontes existentes, principalmente as mais antigas. Buscando colaborar nessa avaliação, o objetivo principal desta tese foi estudar o impacto na redução da vida útil de fadiga devido ao incremento de tráfego de veículos pesados. Foi traçando um comparativo entre a vida útil estimada de projeto, deduzida a partir da consideração do trem tipo de norma, a atual (45t) e a anterior (36t), e uma estimativa de vida útil alternativa, decorrente da consideração de espectros de carregamentos reais obtidos a partir da análise do volume e composição de tráfego de dados oficiais, CONCEPA e DNIT, em quatro postos situados ao longo da BR 290, rodovia federal brasileira. Dois modelos de vigas, foram tomados como referência para as análises, considerando-se para cada uma delas com diferentes comprimentos de vãos. Foram também estudadas simulações de situações com incrementos de veículos com sobrepeso, de fluxo de tráfego, e de efeitos da diminuição da seção resistente por deterioração da armadura por corrosão. O estudo mostra que em função do fluxo de veículos pesados pode resultar um encurtamento significativo da vida útil de estruturas antigas de pequeno porte dimensionadas para o trem tipo de 36t, e para estruturas com balanços dimensionadas para os dois trens tipo considerados.Fatigue is an important degradation process, to which structures under the action of cyclic loading, such as bridges, may be subjected. It consists in a micro-damage accumulation mechanism, which involves the formation and growing of cracks. After a determined number of cycles, it can culminate on the total crack of the material under a much lower stress than its ultimate capacity. The design calculation procedure to prevent that from happening, ensures the working material stress to be much lower than the rupture stress. In such way, minimizing micro-damages, it becomes necessary a very high number of loading cycles to provoke fatigue. Usually, bridge design considers the effect of live loads through a Standard Loading Vehicle, recommended by the Brazilian Code. In real life however, each vehicle results in a different action upon the structure, depending on its total weight and axel distribution. It becomes evident that heavier vehicles are those that fastly consume the structure´s fatigue life, especially for bridges with a relative small self weight. Due to the ever increasing traffic volume and total weight of the vehicles, it becomes preoccupant the situation of many existent bridges, especially the older ones. In this sense, the objective of this work is to study the impact of the increasing traffic of heavy vehicles on the reduction of the remaining bridge fatigue’s life. For that purpose, a comparison was established between two different estimative analyses of a bridge service life expectation. One considers the bridge design specifications contained in the actual (45t) and previous (36t) Brazilian Codes. The other results from the consideration of a real traffic loading observation. Such traffic data was obtained in four checkpoints of a Brazilian federal highway ( BR 290 ), by the federal agencies CONCEPA and DNIT. Two commonly used cross section beams and bridge length were considered for the analysis. With such models, different numerical simulations of increasing vehicle weight and traffic flow were performed. Furthermore, the effects of a reduced section resistance. due to corrosion deterioration of the reinforcement. were also studied. Conclusions show that the increasing traffic of heavy vehicles may result in a significant reduction of a bridge remaining service life. That is more evident for small old bridges designed under the previous Brazilian Code specifications ( 36t ). Also, cantilevered bridge structures designed by the previous and actual Codes may be subjected to such life reduction.
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Giaccio, Craig 1974. "Flange effectiveness in the resistance of shear on RC T-beams subjected to point loads." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5708.
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Cachim, Paulo Barreto. "Experimental and numerical analysis of the behaviour of structural concrete under fatigue loading with applications to concrete pavements." Doctoral thesis, Online version, 1999. http://hdl.handle.net/10216/11314.
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Cachim, Paulo Barreto. "Experimental and numerical analysis of the behaviour of structural concrete under fatigue loading with applications to concrete pavements." Tese, Online version, 1999. http://hdl.handle.net/10216/11314.
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Fassin, Manuel. "Behaviour and modelling of the inelastic response of concrete and steel-concrete infrastructures subjected to low-cycle fatigue." Doctoral thesis, Università degli studi di Trento, 2016. https://hdl.handle.net/11572/369278.
Full textAbstract:
Nowadays, infrastructures are of strategical importance for allowing communication between countries. Owing to its usefulness, the design and the maintenance of bridges, streets and tunnels, which represent the network, become a fundamental issue. In order to investigate the behaviour of infrastructures under different loads, such as gravity, seismic phenomena, thermal differences, and so on, appears essential a comprehensive experimental campaign on scaled and full-scale specimens. In particular, in order to guarantee the safety of citizens, the seismic response of infrastructures under an earthquake requires a careful evaluation of the level of damage of structural elements.
In this thesis, typical case studies are considered, such as a concrete tunnel lining and a composite steel-concrete bridge. In the first part of the thesis, a typical concrete tunnel lining is analysed. In order to investigate the inelastic behaviour of a concrete circular tunnel, several tests were performed. In greater detail, the best Fiber Bragg Grating (FBG) package configuration was obtained by means of monotonic and cyclic tests on substructures. Based on these results, the resulting suitable configuration in a full-scale tunnel test was used to measure deformations with high accuracy. Cyclic test on the full-scale tunnel provided data on the damage of reinforcing concrete and the developing of plastic hinges. With the aim of providing information on the structural safety of a tunnel after an earthquake, a damage index was calculated. In this respect, a nonlinear fiber F.E. model in the OpenSEES environmental was developed. This model calculated the stress in terms of bending moment in concrete sections with the use of experimental curvatures measured by FBGs system. Finally, the damage evolution in the concrete tunnel was reported and commented. In the second part of this thesis, a composite steel-concrete short-medium span bridge is treated. The innovation was the application of the PEER Performance-Based Earthquake Engineering (PBEE) to this type of bridge. Moreover, the use of the Hot-rolled (HRS) steel to manufacture I-girder beams has become an innovation in civil infrastructures in Europe, as much as the use of transversal concrete cross-beams (CCBs) to connect spans. With reference to the hazard selected, a suitable case study was chosen. With the aim of understanding the most critical and stressed parts of the case study, preliminary elastic shell and stick models were developed. After the identification of interesting parts, half-scale subassembly specimens were designed and built. Several quasi-static tests, both monotonic and cyclic, were carried out with the objective of exploring global and local mechanisms in the section owing to low-cycle fatigue phenomena. To detect damage in the connection detail, a refined F.E. model in ABAQUS was developed. Fragility curve parameters of the damage's interest quantities were obtained by fitting experimental and numerical data by means of the Maximum Likelihood Estimation method. The results and the numerical model could be ready for the application of the Performance-Based Earthquake Engineering tool, in which decision variables, such as repair costs, downtime, human life loss and lane closures, were taken into consideration in order to increase the confidence in the design for both engineer and owner's viewpoint.
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Fassin, Manuel. "Behaviour and modelling of the inelastic response of concrete and steel-concrete infrastructures subjected to low-cycle fatigue." Doctoral thesis, University of Trento, 2016. http://eprints-phd.biblio.unitn.it/1754/1/PhD_Thesis_Manuel_Fassin.pdf.
Full textAbstract:
Nowadays, infrastructures are of strategical importance for allowing communication between countries. Owing to its usefulness, the design and the maintenance of bridges, streets and tunnels, which represent the network, become a fundamental issue. In order to investigate the behaviour of infrastructures under different loads, such as gravity, seismic phenomena, thermal differences, and so on, appears essential a comprehensive experimental campaign on scaled and full-scale specimens. In particular, in order to guarantee the safety of citizens, the seismic response of infrastructures under an earthquake requires a careful evaluation of the level of damage of structural elements.
In this thesis, typical case studies are considered, such as a concrete tunnel lining and a composite steel-concrete bridge. In the first part of the thesis, a typical concrete tunnel lining is analysed. In order to investigate the inelastic behaviour of a concrete circular tunnel, several tests were performed. In greater detail, the best Fiber Bragg Grating (FBG) package configuration was obtained by means of monotonic and cyclic tests on substructures. Based on these results, the resulting suitable configuration in a full-scale tunnel test was used to measure deformations with high accuracy. Cyclic test on the full-scale tunnel provided data on the damage of reinforcing concrete and the developing of plastic hinges. With the aim of providing information on the structural safety of a tunnel after an earthquake, a damage index was calculated. In this respect, a nonlinear fiber F.E. model in the OpenSEES environmental was developed. This model calculated the stress in terms of bending moment in concrete sections with the use of experimental curvatures measured by FBGs system. Finally, the damage evolution in the concrete tunnel was reported and commented. In the second part of this thesis, a composite steel-concrete short-medium span bridge is treated. The innovation was the application of the PEER Performance-Based Earthquake Engineering (PBEE) to this type of bridge. Moreover, the use of the Hot-rolled (HRS) steel to manufacture I-girder beams has become an innovation in civil infrastructures in Europe, as much as the use of transversal concrete cross-beams (CCBs) to connect spans. With reference to the hazard selected, a suitable case study was chosen. With the aim of understanding the most critical and stressed parts of the case study, preliminary elastic shell and stick models were developed. After the identification of interesting parts, half-scale subassembly specimens were designed and built. Several quasi-static tests, both monotonic and cyclic, were carried out with the objective of exploring global and local mechanisms in the section owing to low-cycle fatigue phenomena. To detect damage in the connection detail, a refined F.E. model in ABAQUS was developed. Fragility curve parameters of the damage's interest quantities were obtained by fitting experimental and numerical data by means of the Maximum Likelihood Estimation method. The results and the numerical model could be ready for the application of the Performance-Based Earthquake Engineering tool, in which decision variables, such as repair costs, downtime, human life loss and lane closures, were taken into consideration in order to increase the confidence in the design for both engineer and owner's viewpoint.
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Abd, Rahman Norashidah. "Fatigue behaviour and reliability of Extended Hollobolt to concrete filled hollow section." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12909/.
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The need to provide mechanical connection from one side for the Hollow section connection has arisen in a number of fields and has resulted in the development of several types of so-called blind fasteners. An experimental blind bolt called the Extended Hollobolt is giving a good behaviour performance in terms of stiffness, strength and ductility. The strength performance of this system has been investigated under both monotonic and cyclic loading. However, the performance of such connections under fatigue loading is still unknown. The aim of this study was to investigate the behaviour of blind bolt connection to concrete filled hollow section under repeated load. Further aim was to determine the reliability of the Extended Hollobolt to concrete filled hollow section. The study involved conducting an experimental programme and carrying out fatigue life and reliability analysis. The experiment programme tested 52 specimens of bolts connected to concrete filled hollow sections where 36 tests involved Extended Hollobolt, 10 standard Hollobolt and 6 standard bolts (M16). The test specimens were subjected to tensile fatigue load characteristics with varying stress ranges. Mathematical methods are used to analyse the fatigue test data using the normal, lognormal and Weibull distributions. Normal and lognormal distributions are more suitable. Therefore, statistical analysis procedure proposed by Eurocode for the statistical analysis is valid for fatigue test data. Statistical analysis was conducted to establish S-N curves and to predict the fatigue life of the proposed blind bolt. This was then compared to the normative regulation in Eurocode 3. The failure mode of the Extended Hollobolt under repeated loading was found to be similar with standard bolt, which is a very positive outcome. Statistical analysis of fatigue test data showed that the fatigue life of Extended Hollobolt is higher than the theoretical design S-N curve which is recommended by Eurocode 3 part 1-9 for the standard bolt. However, the actual fatigue life for the standard bolt appears to be higher than the proposed blind bolt. A design model for predicting the fatigue life using S-N curve for the Extended Hollobolt is proposed. A reliability analysis using FORM (First Order Reliability Method) analysis shows that Extended Hollobolt is reliable in connections to concrete filled hollow sections where the safety index is 4.2.
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Arana, Villafán Tomás [Verfasser]. "Fatigue of the tension-stiffening effect in reinforced concrete / Tomás Arana Villafán." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2021. http://d-nb.info/1236991435/34.
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El, Ragaby Amr. "Fatigue behaviour of concrete bridge deck slabs reinforced with glass FRP bars." Thèse, [S.l. : s.n.], 2007. http://savoirs.usherbrooke.ca/handle/11143/1795.
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Mackellar, Andrew. "The effect of concrete strength and fibre content on the fatigue performance of Ultra Thin Continuously Reinforced Concrete Pavement (UTCRCP)." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/62778.
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Ultra Thin Continuously Reinforced Concrete Pavement (UTCRCP) is an innovative road paving technology that can have significant advantages over traditional road paving techniques. Full scale testing has shown that UTCRCP can carry in excess of one hundred million E80s (standard 80 kN axle loads). The concrete used for the construction of UTCRCP is high strength and contains steel fibres. The purpose of this study is to investigate the effect of varying the concrete strength and fibre content on the mechanical properties of the concrete used to construct UTCRCP. In this study testing is restricted to laboratory methods. Fibre reinforced concrete is often tested with the same tests as those used for plain concrete. These are not adequate to fully capture the effects of the steel fibres. A number of test methods are used in this study and their suitability and shortcomings are discussed. Additionally, fatigue tests are conducted and a number of performance measures are used to track the fatigue damage. It was found that higher concrete strength and high fibre content did not necessarily result in highest performance in all cases. It was also found that there is not a single concrete strength or fibre content that always results in the optimum performance in all cases. For example the concrete strength and fibre content that produced the best results for tensile strength was not the best mix for energy absorption at high deflections. When selecting the concrete strength and fibre content for use in construction the application of the concrete element must be carefully understood. Based on this the designer can then select which of the concrete performance characteristics are of most importance to the desired application. Once this is done an appropriate concrete strength and fibre content can be selected.Dissertation (MEng)--University of Pretoria, 2017.
Civil Engineering
MEng
Unrestricted
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Restrepo-Velez, Ana M. "Long-Term Performance of Asphalt Concrete Perpetual Pavement WAY-30 Project." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1307042192.
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Carlesso, Débora Martinello. "Flexural fatigue of pre-cracked fibre reinforced concrete: experimental study and numerical modelling." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669488.
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Fibre reinforced concrete (FRC) is recognized as suitable material for structural applications. The number of national codes that have approved it is an evidence. Structures where FRC is generally used can be subjected to fatigue loads and are expected to resist millions of cycles during their service life. Cyclic loads affect significantly the characteristics of materials and can cause fatigue failures. The most demanded cross-sections being cracked under tensile stresses due to direct loads or imposed deformations. Commonly, publications report fatigue behaviour of concrete under compression and are valid for uncracked sections. Imprecision in fatigue prescriptions are reflected through formulation of models that contemplate a probabilistic approach, or an introduction of high safety coefficients within construction codes. The aim of the present doctoral thesis is to perform a structural design oriented analysis on the behaviour of pre-cracked FRC subjected to flexural fatigue loads. FRC with steel and polypropylene fibre with different volume content were investigated by means of three-point bending tests, considering an initial crack width accepted in the service limit state. The mechanical behaviour of FRC were analysed in terms of applied load level, crack opening displacement (CMOD) and fatigue life. The residual flexural tensile strength was assessed after these tests to estimate the impact of the cycles in the remaining resistant capacity of the specimens. Results suggest that the mechanism of crack propagation is independent of the fibre type and content and the monotonic load-crack opening displacement curve might be used as deformation failure criterion for FRC under flexural fatigue loading. The conducted probabilistic approach allows predicting the fatigue strength of concrete reinforced with steel fibres. The findings postulate the proposal of a model to predict the evolution of the crack-opening and the remaining resistant capacity. An optimisation procedure is proposed to derive the model parameters using a limited number of initial load cycles. This doctoral thesis provides knowledge and data that may aid further research and contribute to the future development of design recommendations.El hormigón reforzado con fibra (FRC) se reconoce como material adecuado para aplicaciones estructurales. El número de normativas que lo han aprobado es una evidencia. Las estructuras donde generalmente se usa FRC pueden estar sujetas a cargas de fatiga y se espera que resistan millones de ciclos durante su vida útil. Las cargas cíclicas afectan significativamente a las características de los materiales y pueden causar roturas por fatiga. Las secciones transversales más demandadas se fisuran bajo tensión debido a cargas directas o deformaciones impuestas. Comúnmente, las publicaciones informan del comportamiento de fatiga del hormigón bajo compresión y son válidas para secciones no fisuradas. La imprecisión de las recomendaciones se refleja a través de la formulación de modelos que contemplan un enfoque probabilístico o la introducción de altos coeficientes de seguridad dentro de los códigos de construcción. El objetivo de la presente tesis doctoral es realizar un análisis orientado al diseño estructural sobre el comportamiento del FRC pre-fisurado sometido a cargas de fatiga por flexión. Se investigaron FRC con fibras de acero y polipropileno con diferentes contenidos de fibras mediante pruebas de flexotracción a tres puntos, considerando un ancho de fisura inicial aceptado en el estado límite de servicio. El comportamiento mecánico del FRC se analizó en términos de nivel de carga aplicada, desplazamiento de apertura de fisura (CMOD) y vida útil bajo fatiga. La resistencia residual a flexotracción se evaluó después de los ciclos de fatiga para estimar el impacto de los ciclos en la capacidad de resistencia restante de las muestras. Los resultados sugieren que el mecanismo de propagación de fisuras es independiente del tipo y contenido de fibra y la curva monotónica de CMOD podría ser utilizada como criterio de falla de deformación para FRC bajo carga de fatiga por flexotracción. El enfoque probabilístico realizado permite predecir la resistencia a la fatiga del hormigón reforzado con fibras de acero. Los resultados postulan la propuesta de un modelo para predecir la evolución de la apertura de fisura y la capacidad resistente remanente. Se propone un procedimiento de optimización para derivar los parámetros del modelo utilizando un número limitado de ciclos de carga inicial. Esta tesis doctoral proporciona conocimiento y datos que pueden ayudar a futuras investigaciones y contribuir al desarrollo futuro de recomendaciones de diseño.
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Braimah, Abass. "Long-term and fatigue behaviour of carbon fibre reinforced polymer prestressed concrete beams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/NQ54403.pdf.
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Abbas, Safeer. "Analytical study of corroded steel-FRP confined concrete bond under fatigue cyclic loading." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/25801.
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The steel-concrete bond and the cracking behaviour of concrete affect the performance of reinforced concrete structures. This is due to the fact that the transfer of forces between the steel and the concrete are accomplished through the bond. The bond between the steel and the concrete is affected by many factors such as corrosion of reinforcement, type of applied loading, and the confinement level. Reinforcement corrosion is one of the primary causes of the loss of steel-concrete bond. On the other hand, an accumulation of bond damage occurs due to the application of fatigue cyclic loading, as in the case of bridges and marine structures. It is known that fibre reinforced polymer (FRP) confinement improves the bond strength, even in the case of corroded reinforcing steel bars.
The objective of this thesis was to develop an analytical tool for structural engineers to evaluate the corroded steel-FRP confined concrete bond under fatigue cyclic loading. Two models have been developed; 1) slip-fatigue model; and 2) bond stress-slip model. These models considered the effect of corrosion of reinforcement, the external confinement provided by the FRP sheets, and the fatigue cyclic loading.
Slip after ‘N’ number of cycles for unwrapped and FRP wrapped cases were developed as a function of the initial slip, the final slip, and the fatigue bond life. These models were capable of capturing the experimental behaviour reported in the literature. Slip-life models for unwrapped and FRP wrapped beam specimens were developed using non linear regression analysis.
Harajli et al. (2004) static bond stress-slip law was modified in order to model the bond stress-slip behaviour for the unwrapped and FRP wrapped beam specimen under monotonic and cyclic loading. The proposed cyclic bond stress-slip behaviour followed the monotonic bond stress-slip envelope and satisfactorily modeled the experimental behaviour.
From the principles of statics of bond and using the derived cyclic bond stress-slip envelope, an equation to calculate the required development length of steel reinforcement was derived. The proposed equation is dependent on the material and the geometrical properties of a structural member. The derived equation was able to satisfactory predict the fatigue bond life.
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Othman, Ayman Mahmoud. "Mechanical performance and fatigue crack growth behavior of polymer-modified asphalt concrete mixtures." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058531669.
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Reberg, Andrew Steven. "An Anisotropic Damage Mechanics Model for Concrete with Applications for Fatigue Loading and Freeze-Thaw Effects." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26994.
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It is well known that the formation and propagation of microcracks within concrete is anisotropic in nature, and has a degrading effect on its mechanical performance. In this thesis an anisotropic damage mechanics model is formulated for concrete which can predict the behavior of the material subjected to monotonic loading, fatigue loading, and freeze-thaw cycles. The constitutive model is formulated using the general framework of the internal variable theory of thermodynamics. Kinetic relations are used to describe the directionality of damage accumulation and the associated softening of mechanical properties. The rate independent model is then extended to cover fatigue loading cycles and freeze-thaw cycles. Two simple softening functions are used to predict the mechanical properties of concrete as the number of cyclic loads as well as freeze-thaw cycles increases. The model is compared with experimental data for fatigue and freeze-thaw performance of plain concrete.DOT-MPC grant
Department of Civil Engineering, North Dakota State University
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Petrou, Michael Frixos. "Fatigue performance of AASHTO and Ontario design for non-composite reinforced concrete bridge decks." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1060797619.
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Ofori-Abebresse, Edward Kwame. "Fatigue resistance of hot-mix asphalt concrete (HMAC) mixtures using the calibrated mechanistic with surface energy (CMSE) measurements approach." Thesis, Texas A&M University, 2006. http://hdl.handle.net/1969.1/4136.
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Fatigue cracking is one of the fundamental distresses that occur in the life of a Hot Mix Asphalt Concrete (HMAC) pavement. This load induced distress leads to structural collapse of the entire pavement ultimately and can only be remedied by rehabilitation. There is the need, therefore, for a total understanding of the phenomenon to be able to counter its occurrence. The fatigue resistance of hot mix asphalt concrete (HMAC) has been estimated using approaches ranging from empirical methods to mechanistic-empirical methods to purely mechanistic methods. A continuum mechanics based approach called the Calibrated Mechanistic with Surface Energy (CMSE) measurements was developed at Texas A&M University and recommended after comparison with other approaches in predicting fatigue lives of two Texas HMAC mixtures. The CMSE approach which includes fundamental material properties such as fracture, aging, healing, and anisotropy has been shown to effectively model the parameters that affect the performance of HMAC pavements exposed to repetitive traffic loads. Polymer modified asphalt (PMA) improves pavement performance by providing additional resistance to the primary distresses in flexible pavements, including permanent deformation or rutting, thermal cracking, and fatigue cracking. In this research, the CMSE approach was utilized to estimate the fatigue resistance of HMAC fabricated with asphalts modified with Styrene-butadiene-Styrene (SBS) co-block polymer. These HMAC mixtures were fabricated from materials used on three different road sections in Texas and one test pavement in Minnesota. The CMSE approach was validated as an effective approach for estimating the fatigue resistance of HMAC mixtures with PMA. The effect of oxidative aging on the fatigue resistance of the HMAC mixtures was also verified. Oxidative aging of the mixtures resulted in a corresponding decrease in mixture fatigue resistance. In addition, for two HMAC mixtures with the same binder content and aggregate gradation, the mixture with the softer of the two Performance Grade (PG) binders exhibited greater fatigue resistance. The use of the Utility Theory revealed the possible effects of aggregate geometric properties on the HMAC mixture properties and consequently on their fatigue resistance.
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Carnio, Marco Antonio. "Propagação de trinca por fadiga do concreto reforçado com baixos teores de fibra." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264892.
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Orientador: Itamar FerreiraTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: O concreto reforçado com fibras (CRF) é um compósito constituído de duas fases: concreto (matriz) e fibras (reforço). As fibras são elementos descontínuos de vários aspectos geométricos e materiais, destacando-se atualmente as fibras metálicas (aço) e as fibras sintéticas (polipropileno). Em geral, os teores de fibras em volume adicionados à matriz se dividem em: baixos teores - até 0,5%; médios teores - entre 0,5% e 1% e altos teores - acima de 1%. Dentre as aplicações do CRF com baixos teores, a utilização em pavimentos de concreto é a mais significativa, cuja solicitação predominante é cíclica. O estudo da fadiga se divide em iniciação da trinca, propagação da trinca e fratura final, e a vida em fadiga (Nf) é caracterizada pela soma do número de ciclos até a fratura. Dessa forma, como no estudo da fadiga do CRF a maioria dos trabalhos se concentra na obtenção de seu comportamento por meio das curvas S-N (tensão em função do número de ciclos até a fratura), este trabalho tem como objetivo estudar experimentalmente a propagação da trinca por fadiga dos CRFs com baixos teores, por meio de ensaios de flexão em corpos-de-prova prismáticos de seção quadrada, submetidos a carga cíclica com freqüência de 20 Hz e razão de carga R = 0,1, representando seu comportamento pelas curvas da/dN-_K (taxa de propagação de trinca por fadiga em função da variação do fator de intensidade de tensão), ensaios de flexão em corpos-de-prova prismáticos de seção quadrada, submetidos a carga monotônica, representando seu comportamento pelas curvas carga monotônica-deslocamento de abertura da boca da trinca (CMOD) e o estudo macroscópico da seção fraturada desses concretos, após cargas cíclicas e monotônica para avaliação dos mecanismos de fratura da seção, visando melhor entender a contribuição dessas adições nos CRFs submetidos a cargas cíclicas. Os resultados indicam que o CRF com fibras de polipropileno de 54 mm apresenta melhor desempenho à propagação de trinca por fadiga, com comportamento equivalente aos CRFs com fibras de aço de 60 mm e que, o CRF com fibras de aço de 35 mm apresenta melhor desempenho dentre todos tipos e teores de fibras estudadas. Quanto ao comportamento à carga monotônica, o desempenho dos CRFs com fibras de aço de 60 mm se mostrou melhor dentre os estudados, desempenho esse não confirmado quanto à propagação de trinca por fadiga. Também se conclui que a ancoragem das fibras interfere no comportamento dos CRFs às cargas monotônica e cíclica, sendo que a degradação da ancoragem mecânica nas fibras de aço submetidas a cargas cíclicas penaliza mais os CRFs com fibras de aço de 60 mm quanto ao desempenho à propagação de trinca por fadiga. Na avaliação da superfície de fratura dos CRFs, verificou-se que a adição de fibras interfere nessa superfície, apresentando-se mais plana para os CRFs com fibras sintéticas e mais irregular para os CRFs com fibras de aço.
Abstract: The fibers reinforced concrete (FRC) is a composite formed by two phases: concrete (matrix) and fibers (reinforce). The fibers are discontinuous elements of several geometric aspects and materials, currently detaching the metal fibers (steel) and the synthetic fibers (polypropylene). In general, the contents of fibers in volume added to the matrix are separated in: low contents - up to 0.5%; medium contents - between 0.5% and 1% and high contents - above 1%. Among the applications of the FRC with low contents, the usage in concrete pavements is the most significant, which predominant request is cyclic. The study of fatigue is divided into initialization of crack, propagation of crack and final fracture and the life in fatigue (Nf) is characterized by the sum of number of cycles up to the fracture. In this way, as in the study of fatigue of FRC the majority of the work focuses on obtaining their behavior through the S-N curves (tensile due to the number of cycles up to the fracture) this work has as objective to study experimentally the fatigue crack propagation of the low contents FRC, by means of testing the flexure in prismatic samples of square section, subjected to a cyclic load of 20 Hz frequency and load ratio R=0.1, representing their behavior through the da/dN-_K curves (rate of fatigue crack propagation in lights of the variation of the intensity of the tensile), by testing the flexure in prismatic samples of square section, subjected to a monotonic load, representing their behavior through the curves monotonic load - cracking mouth opening displacement (CMOD) and the macroscopic study of the fracture section, to better understand the contribution of these additions into the FRC subjected to a cyclic load. The results indicate that the FRC with synthetic fibers of 54 mm size shows a better performance for fatigue crack propagation, with equivalent behavior as of the FRCs with steel fibers of 60 mm size and that the FRC with steel fibers of 35 mm size shows even a better performance among all types and contents of fibers studied. About the behavior of the monotonic load, the performance of the FRCs with steel fibers of 60 mm size was better among all studied behaviors, but that performance is not confirmed regarding the fatigue crack propagation. Also concludes that the anchorage of the fibers interfere in the behavior of both FRC subjected to monotonic load and cyclic load, and the degradation of the mechanic anchorage in the steel fibers, subjected to a cyclic loads punish more the FRCs with the steel fibers of 60 mm regarding to their performance of fatigue crack propagation. Evaluating the fracture surfaces of the FRC, verify that the addition of fibers interfere on these, resulting in a more flat to the FRC with synthetic fibers and more irregular to the FRCs with steel fibers.
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Heller, Bryan Earl. "Fatigue response of pretensioned concrete beams." 2004. http://hdl.handle.net/10945/11048.
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The objective of this thesis is to discuss the suitability of using a extreme fiber concrete tensile stress of 12 * (f'c (exp 1/2) calculated using uncracked section analysis as a limit state criterion for evaluating prestressed concrete highway bridges as a part of required serviceability inspections. This thesis reviews strand fatigue test results as well as fatigue test results of prestressed beams from past experiments. Test results of four new prestressed beam fatigue tests are reported and analyzed. Finally, a recommendation is made that beam fatigue analysis should be based on the stress range of the prestressing strands, unless the calculated extreme fiber concrete tensile stress is limited to less than 3 *f'c(exp 1/2) based on uncracked section analysis.
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Chien, C. F., and 簡慶發. "Fatigue Strength of Prestressed Concrete Beams." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/82665088589316600243.
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Morrill, Paul Baker. "Tension fatigue analysis of fiber reinforced concrete." 1990. http://catalog.hathitrust.org/api/volumes/oclc/23686447.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1990.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 78-81).
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Hagenberger, Michael John Wood Sharon L. Kreger Michael E. "Consideration of strand fatigue for load rating prestressed concrete bridges." 2004. http://wwwlib.umi.com/cr/utexas/fullcit?p3142734.
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JIANG, WEN-GING, and 江文卿. "The fatigue strength of double reinforced concrete beams." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/28623119442638218342.
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Jurado, Gonzalo. "Fatigue life assessment on composite concrete-steel bridges." Master's thesis, 2017. http://hdl.handle.net/10316/82869.
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Dissertação de Mestrado em Construção Metálica e Mista apresentada à Faculdade de Ciências e TecnologiaFatigue is an important consideration in the design of bridges, especially those made of steel. Cycles resulting from the passage of a truck over a bridge depend essentially on bridge type, detail location, span length and vehicles axles configuration. Moreover, as bridges form the keystone of transport networks, their safe operation with minimal maintenance closures is paramount for efficient operation. Yearly increases in the volume of heavy traffic mean a higher number of fatigue damaging load cycles, which leads to taking appropriate measures and finding sustainable solutions, with reduced environmental, economic and social impacts.This work is focused on developing a software tool for the design and assessment of composite concrete-steel bridges under fatigue, according to Eurocodes. The type of bridge used for this project is limited to a road-girder-bridge. Design approaches include both the damage equivalent factor method and the damage accumulation method. For the latter, an algorithm was developed which simulates truck passages over a bridge model and calculates fatigue load effects using the axle positions recorded in real time. This information could serve as an identification tool for bridges where fatigue is likely to be a problem and could form part of a full bridge management framework in the future.Furthermore, the program is applied into a real case study, in order to compare the results and evaluate its efficiency and accuracy. Finally, conclusions are drawn and future work is proposed, leaving space for improvements and new challenges.
Fatigue is an important consideration in the design of bridges, especially those made of steel. Cycles resulting from the passage of a truck over a bridge depend essentially on bridge type, detail location, span length and vehicles axles configuration. Moreover, as bridges form the keystone of transport networks, their safe operation with minimal maintenance closures is paramount for efficient operation. Yearly increases in the volume of heavy traffic mean a higher number of fatigue damaging load cycles, which leads to taking appropriate measures and finding sustainable solutions, with reduced environmental, economic and social impacts.This work is focused on developing a software tool for the design and assessment of composite concrete-steel bridges under fatigue, according to Eurocodes. The type of bridge used for this project is limited to a road-girder-bridge. Design approaches include both the damage equivalent factor method and the damage accumulation method. For the latter, an algorithm was developed which simulates truck passages over a bridge model and calculates fatigue load effects using the axle positions recorded in real time. This information could serve as an identification tool for bridges where fatigue is likely to be a problem and could form part of a full bridge management framework in the future.Furthermore, the program is applied into a real case study, in order to compare the results and evaluate its efficiency and accuracy. Finally, conclusions are drawn and future work is proposed, leaving space for improvements and new challenges.
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"Fatigue life of partially prestressed concrete bridge girders." Tulane University, 1992.
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Prestressed concrete is one of the most common materials used in modern bridge construction. Nearly 50% of new highway bridges are constructed of prestressed concrete. Current U.S. bridge design codes do not allow cracking under service load in prestressed concrete members Partially prestressed concrete is a type of concrete construction in which some prestressing force is applied to the steel reinforcement. For the purposes of this study, partial prestressing will be considered as prestressed concrete in which cracking is allowed under service loading. This cracking increases the possibility of fatigue failure of the member under repetitive loading, such as that encountered by bridge structures The purpose of this project is to develop an analysis model to predict the fatigue life of bonded, pretensioned, partially prestressed concrete girders carrying highway traffic loadings. This study is analytical, with data on the fatigue behavior of partially prestressed concrete beams coming from earlier tests by other researchers This project begins by reviewing some of the earlier research on partially prestressed concrete beams, fatigue properties of concrete, reinforcing steel and prestressing strand, and highway bridge loadings. An analytical model of the behavior of a partially prestressed beam under fatigue loading is developed. Time-dependent factors such as creep, shrinkage, and prestressing steel relaxation are included in the analysis. Cumulative damage to the prestressing strand and reinforcing steel is calculated using Miner's rule. With this cumulative damage result, the fatigue life of the girder is predicted. The fatigue analysis model is verified using the results of laboratory constant and variable amplitude fatigue tests An example series of partially prestressed girders is designed and analyzed under highway loading using the fatigue analysis model Only flexural behavior is considered in this report. Shear fatigue is not included in this investigationacase@tulane.edu
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Hagenberger, Michael John. "Consideration of strand fatigue for load rating prestressed concrete bridges." Thesis, 2004. http://hdl.handle.net/2152/1209.
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