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1
Baczkowski, Bartlomiej Jan. "Steel fibre reinforced concrete coupling beams /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20BACZKO.
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Elsaigh, W. A. "Steel fiber reinforced concrete ground slabs : a comparative evaluation of plain and steel fiber reinforced concrete ground slabs." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-03032006-154355/.
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Jeyarupalingam, Nadarajah. "Steel, steel/concrete composite and reinforced concrete beams and columns exposed to fire." Thesis, City University London, 1996. http://openaccess.city.ac.uk/7766/.
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This thesis describes the development of a numerical method for the structural analysis of beams and columns subjected to a non-linear variation of temperatures in all three directions. The numerical method allows for analysis of a wide variety of cross sections with a number of materials and members with varying cross section along the length. The member can be subjected to any combination of axial load, end moments, lateral load and bi-axial bending. Any fire temperature characteristic can be specified. The numerical method has been validated by comparing results with a number of experimental results on steel, concrete and composite beams and columns from literature and with the experiments carried out under this research programme. Experiments were carried out on seven columns with non-uniform temperature distribution along the length and across the depth. The test rig was designed and manufactured at City University. Electrical heating elements were used to heat the specimens. To obtain a comprehensive temperature profile of the test columns several thermocouples were used. Deflection measurements were made using displacement transducers placed at different positions. Using the new method of analysis a simple design method for steel columns subjected to non-uniform temperature distribution across the depth of the section has been developed. The method has been validated with a number of results on H-section columns from numerical experiments performed using the computer programs developed in this thesis. Another parametric study has been carried out to improve the inherent fire resistance capacity of Slimflor beams. It is concluded that it is possible to design a Slimflor beam with higher fire resistance capacity than the current rating of 60 minutes by introducing steel reinforcing bars at appropriate place.
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Horne, Adrian Thomas. "Microstructure of interfaces in steel reinforced concrete." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411148.
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Darwish, I. Y. S. "Steel fibre-reinforced concrete elements in shear." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375129.
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Elsaigh, Walied Ali Musa Hussien. "Modelling the behaviour of steel fibre reinforced concrete pavements." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-01292008-175515.
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Machado, Rafael Ignacio. "Experimental investigation of steel tubed reinforced concrete columns." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19457.
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Aoude, Hassan. "Structural behaviour of steel fibre reinforced concrete members." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18676.
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A series of full-scale axial compression tests was conducted on RC and SFRC columns. The specimens, which were detailed with varying amounts of transverse reinforcement, were cast using a self-consolidating concrete (SCC) mix that contained various quantities of fibres. The results demonstrate that the addition of fibres leads to improvements in load carrying capacity and post-peak response. The results also show that the addition of steel fibres can partially substitute for the transverse reinforcement in RC columns, thereby improving constructability while achieving significant confinement. Analytical models for the prediction of the load-strain response of SFRC columns are presented and validated with the experimental results. The tensile behaviour of SFRC members reinforced with a single reinforcing bar was also studied. The results indicate that the addition of fibres leads to improvements in tension stiffening and crack control. A procedure for predicting the response of tension members, accounting for the presence of fibres, is presented. Experimental investigations were carried out on a series of RC and SFRC beams. The effects of steel fibres on shear capacity, failure mechanism and crack control are studied. The results show that the addition of steel fibres leads to improvements in load carrying capacity and can lead to a more ductile failure. A simple procedure that can be used to predict the ultimate shear capacity of SFRC beams is introduced and validated using results from other researchers.Une série d'essais a été réalisée sur des poteaux de taille réelle soumis à des charges axiales. Les échantillons, qui avaient des quantités variables d'armature transversale, ont été construits en utilisant un béton auto-plaçant qui contenait une quantité variable de fibres métalliques. Les résultants de cette étude expérimentale démontrent que la présence des fibres influence positivement la capacité portante des poteaux. De plus, les résultats montrent que l'utilisation d'un béton renforcé de fibres métalliques (BFM) peut s'avérer une solution appropriée pour assurer une ductilité adéquate aux poteaux. L'auteur propose des modèles analytiques pour prédire le comportement de poteaux chargés uniaxialement. Le comportement sous tension d'éléments en BFM armés d'une seule barre a été étudié. Les résultats montrent que la présence de fibres améliore la résistance en tension. Une procédure pour la prédiction de la réponse des éléments soumis sous tension, prenant en compte la présence de fibres métalliques, est présentée. Des recherches expérimentales furent entreprises afin d'étudier le comportement de poutres sans étriers. L'influence de la présence de fibres sur le développement de fissures ainsi que les mécanismes de ductilité et de rupture est discutée. Les résultats montrent que l'ajout de fibres améliore la capacité portante et la ductilité des poutres. Une procédure est suggérée afin de déterminer la capacité portante de poutres construits avec BFM.
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Pros, Parés Alba. "Numerical approach for modeling steel fiber reinforced concrete." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/83724.
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One alternative to overcome the main drawbacks of plain concrete in tension (its brittleness and weakness) is Steel Fiber Reinforced Concrete (SFRC), a technique introduced in the 70's, which consists of adding steel fibers into the concrete matrix.
Due to the presence of the steel fibers into the concrete matrix, the residual strength and the energy dissipation of the material increase. Moreover, once a crack appears in the concrete, the steel fibers sew this fissure. The shape, the length and the slenderness of the fibers influence on the SFRC behavior. Moreover, the distribution and the orientation of the fibers into the concrete domain must be taken into account for characterizing the material.
In order to characterize the behavior of SFRC, a numerical tool is needed. The aim is to simulate the most standard and common tests (direct and indirect tension tests, flexural test, double punch tes,¿) and more complex setups.
This thesis proposes a numerical tool for modeling SFRC avoiding homogenized models (not accurate enough) and conformal meshes (too expensive). Therefore, the numerical tool accounts for the actual geometry of the fibers, discretized as 1D bars nonconformal with the concrete bulk mesh (2D or 3D domains). The two materials, corresponding to the concrete bulk and the fiber cloud, are defined independently, but coupled by imposing displacement compatibility. This compatibility is enforced following the ideas of the Immersed Boundary methods.
Two different models are considered for modeling the concrete bulk (a continuous one and a discontinuous one). The parametric study of each model is done for only plain concrete, before the addition of the steel fibers.
A phenomenological mesomodel is defined for modeling steel fibers, on the basis of the analytical expressions describing the pullout tests. This phenomenological mesomodel not only describes the behavior of the steel fibers, but also accounts for the concrete-fiber interaction behavior. For each fiber, its constitutive equation is defined depending on its shape (straight or hooked) and the angle between the fiber and the normal direction of the failure pattern.
Both 2D and 3D examples are reproduced with the proposed numerical tool. The obtained results illustrate the presence of the steel fibers into the concrete matrix. The shape of the fiber influences of the SFRC behavior: the residual strength is higher for hooked fibers than for straight ones. Moreover, increasing the quantity of fibers means increasing the residual strength of the material.
The obtained numerical results are compared to the experimental ones (under the same hypothesis). Therefore, the proposed numerical approach of SFRC is validated experimentally.
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Abdullah, Mohd Sabri. "Reinforced concrete beams with steel plates for shear." Thesis, University of Dundee, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342881.
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Jones, Peter A. "Flexural modelling of steel fibre reinforced sprayed concrete." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/6885.
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A current limitation on the structural use of steel fibre reinforced sprayed concrete (that equally applies to cast steel fibre reinforced concrete) is a distinct lack of accepted design rationales and codes of practice. The research presented here describes the development of a model, based on conventional principles of mechanics, for predicting the flexure behaviour of a wet process sprayed concrete reinforced with deformed steel fibres. The model uses a stress-block diagram to represent the stresses (and resultant forces) that develop at a cracked section by three discrete stress zones: (a) a compressive zone; (b) an uncracked tensile zone; and (3) a cracked tensile zone. By using this concept it is shown that the stress-block diagram, and hence flexural behaviour, is a function of six principal parameters: the compressive stress-strain relation; the tensile stress-strain relation; fibre pull-out behaviour; the number and distribution of fibres across the crack in terms of their positions, orientations and embedment lengths; and the strain/crack-width profile in relation to the deflection of the beam. An experimental investigation was undertaken to obtain relationships for these parameters. Five tests were identified and developed as part of this investigation: a single fibre pull-out test; a compression test; a strain analysis test; a fibre distribution analysis test; and a flexural toughness test. The majority of the investigation used cast (as opposed to sprayed) specimens so that the test variables under investigation could be better controlled. Spraying trials were also successfully undertaken to demonstrate the pumpability and sprayability of the adopted mixes and to verify the use of the model for both cast and sprayed specimens. The results of the modelling analysis showed a reasonable agreement between the model predictions and experimental results in terms of the load-deflection response. However, the accuracy of the model is probably unacceptable for it to be currently used in design. A subsequent analysis highlighted the single fibre pull-out test and the sensitivity of the strain analysis tests as being the mai n cause of the discrepancies. As a result, recommendations are made for how the model might be improved. Overall this research has provided a valuable insight into the reinforcing mechanisms, fracture processes and characteristics of failure associated with the flexural behaviour of steel fibre reinforced concrete. It is envisaged that the proposed model could form the basis of a design rationale which requires only the matrix strength, fibre type, fibre content, beam size and loading geometry as design input parameters. Consequently, it could offer a much needed link between flexural toughness performance and structural design, by allowing designers to make informed choices regarding the mix design in order to meet the ultimate and serviceability requirements of a particular application.
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Gurusamy, K. "The marine durability of steel fibre reinforced concrete." Thesis, University of Aberdeen, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234802.
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Metaferia, Ineku Amhayesus. "Characterization of Steel Corrosion Products in Reinforced Concrete." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42128.
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Steel corrosion is one of the major distress mechanisms that causes the deterioration of reinforced concrete structures around the world. It is an electrochemical reaction between the reinforcing steel and the surrounding concrete that produces a mass loss of the metal. Through the process of corrosion in reinforced concrete, iron ions get oxidized to form corrosion products (CP). Although multiple experiments and studies have been developed to understand the rheological behavior of corrosion products, this topic stays inconclusive. This work aims to characterize corrosion products at micro-scale in order to trace the progress of the formation of rust, to determine its nature and to analyse its rheological behavior in reinforced concrete. An experimental procedure to produce CP in the laboratory is also presented in this research. In addition, material characterization methods have been used to identify the iron oxide phases present in CP, determine their viscosity and rheological behavior and to study how CP flows in a porous media. In order to identify the different stages in the corrosion process, the CP was analysed at 2, 4, 6 and 8 weeks. The experiments identified four phases of iron oxide for each period. Furthermore, it was found that CP behaves as a shear-thinning slurry and as a result, its viscosity decreases with the applied shear rate. In addition, the damage caused by CP on concrete depends on the w/c ratio of the concrete mix and the exposure time to a corroding environment. The rebar mass loss results show that CP is formed in layers around the rebar, and the flow of each CP layer can differ.
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Jafarifar, Naeimeh. "Shrinkage behaviour of steel-fibre-reinforced-concrete pavements." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/7475/.
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The use of steel fibres extracted from waste tyres as reinforcement for concrete pavements has been developed at the University of Sheffield. The EU funded EcoLanes Project (Economical and sustainable pavement infrastructure for surface transport) undertook extensive research and developed solutions for Steel-Fibre-Reinforced-Concrete (SFRC) pavements with a particular focus on using recycled steel fibres and roller compacted concrete. The current research project ran alongside the EcoLanes project and aimed at contributing towards the development of design guidelines for pavements reinforced with recycled steel fibres. It was achieved through a study on the restrained shrinkage behaviour of Recycled-Steel-Fibre-Reinforced-Roller-Compacted-Concrete (R-SFR-RCC) pavements, and its consequent effect on the load bearing capacity and fatigue performance of pavements. The work in this thesis is mainly based on numerical investigations, but experiments were carried out to obtain the material properties (moisture transport, free shrinkage and mechanical). These basic physical properties were extracted from test results, using inverse analysis. The extent of distress induced by drying shrinkage was evaluated using moisture transport analysis coupled with stress analysis. The effect of shrinkage distress on the load bearing capacity of the pavement was investigated in a comparative way with and without shrinkage. Fatigue test results were also used to study the long-term load-bearing capacity. It was found that the rate of drying and consequent moisture diffusivity in SFRC is higher than for plain concrete and in RCC it is higher than for CC. Moisture diffusivity varies in the range of 0-5 mm2/day for moisture contents lower than 87-92% and then sharply increases to 30 mm2/day for saturated concrete. Free shrinkage is lower for SFRC compared with plain concrete, at early ages. RCC free shrinkage develops at a more uniform rate compared to CC. For the studied SFR-RCC pavement, surface micro-cracks are formed predominantly due to curling (with opening density of 0.69 mm/m) potentially forming micro-cracks (0.014 mm-0.056 mm width) spaced at 20 mm-60 mm. Cracking at the top surface initiates from the beginning of drying, and stabilises after 180 days. Shrinkage cracking penetrates down to around a quarter of the slab thickness, and the tensile strength at the top surface reduces 50% of the maximum strength; whereas based on the Concrete Society TR34, the strength reduces by 30% at the surface and drops linearly to zero at half depth. The current study found that the stress induced by curling is dominant, compared to that induced by external restraints. Shrinkage induced cracks was found to reduce the ultimate load bearing capacity and the fatigue capacity of the pavement by up to 50%.
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Ali, Ahsan. "Bond behavior of lightweight steel fibre-reinforced concrete." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2017. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-230104.
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This research was undertaken for studying the bond behaviour of Lightweight Fibre-reinforced Concrete (LWFC). Lightweight concrete is inherently weak in tension and has higher brittleness than the conventional concrete. To improve these and other properties, it is generally reinforced with deformed bars and fibres. There are number of studies that favour the use of Steel fibres, however such studies are mainly focused either on normal weight concrete or on the mechanical properties of different concretes. There are also different committee reports and in some cases specific sections of codes that specifically deal with the normal weight fibre-reinforced concrete.
However, such is not the case with lightweight fibre-reinforced concrete; there is limited literature available especially on the Bond of lightweight fibre-reinforced concrete.
In current research work effect of fibres is studied on the bond behaviour of the lightweight reinforced concrete. Since most of code provisions for bond are based on experimental work originally carried out on conventional concrete, effect of fibres on bond of conventional concrete was therefore also included in present research domain.
Main bond tests were carried out using Pull-out test methodology. Test results indicate that the ultimate bond strength of conventional concrete when reinforced with steel fibres increased by 29%. However due to very low density and high porosity of lightweight aggregates, no significant improvement on bond strength of LWFC, as a result of fibres’ addition could be observed. Nevertheless, there is noteworthy improvement in the post-cracking bond strength of LWFC. Besides this, current bond-stress slip law as defined by Model Code 2010 does not reflect the positive effect of fibres, hence some modifications are suggested.
It is also found that among the existing code expressions for estimation of bond strength, expression proposed by Model Code 2010 presents better results and its effectiveness can be further increased if fibre factor and factor for lightweight concrete are considered.
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Cheng, Pak Cheung. "Shear capacity of steel-plate reinforced concrete coupling beams /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20CHENG.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 241-245). Also available in electronic version. Access restricted to campus users.
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Agar, Mehmet. "Strengthening Of Reinforced Concrete Frames By Using Steel Bracings." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609664/index.pdf.
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Structures in high seismic risk areas may be susceptible to severe damage in a major earthquake. Structures designed to meet older code requirements may be at even greater risk. When these structures are evaluated with respect to current code criteria, it is observed that they lack of lateral strength and/or ductility. Since safety and economic considerations are major problems, these structures become viable candidates for retrofit and seismic strengthening.
For the variety of structures and possible deficiencies that arise, several retrofitting techniques can be considered. Diagonal bracing system is one of the retrofitting techniques and it provides an excellent approach for strengthening and stiffening existing building for lateral forces. Also, another potential advantage of this system is the comparatively small increase in mass associated with the retrofitting scheme since this is a great problem for several retrofitting techniques.
In this study, the use of steel bracing for the strengthening of low, intermediate, and relatively high rise reinforced concrete frames are investigated analytically. The ultimate lateral load capacities of the strengthened frames are determined by a load controlled push-over analysis. The post-tensioning effect of preloading is also investigated.
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Song, Fanbing [Verfasser]. "Steel Fiber Reinforced Concrete Under Concentrated Load / Fanbing Song." Aachen : Shaker, 2017. http://d-nb.info/1138178888/34.
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Laranjeira, de Oliveira Filipe. "Design-oriented constitutive model for steel fiber reinforced concrete." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/6174.
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En los últimos años la industria viene exigiendo el empleo del hormigón reforzado con fibras de acero (HRFA) en aplicaciones estructurales. Debido al hecho de que la resistencia pos-fisuración del material es relevante, la capacidad de coser fisuras concedida por las fibras puede permitir la sustitución, parcial o total, de la armadura de acero convencional. Por consiguiente, una adecuada caracterización del comportamiento a tracción uniaxial del HRFA es de gran interés. Sin embargo, a pesar de la amplitud de trabajo de investigación y de la reciente elaboración de normativas, no existe un consenso respecto al modelo constitutivo a ser empleado en el diseño del HRFA.El cosido de las fibras de acero en las fisuras mejora la tenacidad y la durabilidad del hormigón. El HRFA es un material que, generalmente, presenta una resistencia residual a tracción en régimen fisurado. Sin embargo, en algunas situaciones, el HRFA puede desarrollar endurecimiento en flexotracción debido a su aptitud en redistribuir esfuerzos en la sección de fisura. Estas características vienen contribuyendo para un interés creciente así como un incremento del número de aplicaciones de este material.
En esta tesis doctoral se desarrolla un método directo y lógico para predecir la respuesta a tracción del HRFA para el diseño estructural. Mientras que la comprensión del comportamiento del material se consigue por medio de una investigación experimental, la formulación del nuevo modelo constitutivo se obtiene con un estudio segmentado del comportamiento del material en niveles de menor complejidad y, en seguida, con la caracterización de cada uno de ellos hasta conseguir explicar la respuesta a tracción del HRFA.
Esta tesis está dividida en cinco partes principales: I) Identificación de las motivaciones. II) Obtención de resultados a tracción uniaxial para comprender los principales mecanismos que controlan la resistencia pos-fisuración. III) Desarrollo de dos modelos para predecir la respuesta al arrancamiento de fibras de acero inclinadas, que cubren fibras rectas y con ganchos. IV) Investigación detallada de la orientación de las fibras al nivel individual mediante análisis estadísticos. Luego, aspectos prácticos asociados al proceso de producción son integrados en una metodología innovadora para predecir la orientación de las fibras. V) Formulación y validación del nuevo modelo constitutivo, con base en las Partes III y IV, con los resultados experimentales de la Parte II. El comportamiento a tracción se evalúa mediante un estudio paramétrico y se proponen expresiones ingenieriles para el diseño y optimización (EEDO).
El modelo constitutivo propuesto se distingue de estudios anteriores en varios aspectos y define una nueva filosofía para el diseño de elementos de HRFA. Este modelo es un método directo y práctico para obtener el comportamiento a tracción del material mediante parámetros con sentido físico y basado en conceptos claros: arrancamiento y orientación de las fibras.
Una de las principales aportaciones de este trabajo es la capacidad de predecir curvas tensión-apertura de fisura que reflejan una combinación específica de las propiedades de la matriz y de las fibras empleadas. Además, se introduce una filosofía innovadora en el diseño debido a la incorporación del proceso de producción, las propiedades en estado fresco y el elemento a construir en la definición del diagrama constitutivo.
In the last years, the industry has been demanding for the use of steel fiber reinforced concrete (SFRC) in structural applications. Because the post-cracking strength of this material is not negligible, the crack-bridging capacity provided by fibers may replace, partial or completely, conventional steel reinforcement. Therefore, an appropriate characterization of the SFRC uniaxial tensile behavior is of paramount interest. However, in spite of the extensive research and standards recently advanced, there is no agreement on the constitutive model to be used for the design of SFRC.
The crack-bridging capacity provided by steel fibers improves both the toughness and the durability of concrete. Conventional SFRC is a material which presents softening response under uniaxial tension, but may develop hardening behavior in bending due to its ability to redistribute stresses within the crosssection.
These evidences have been contributing to an increasing interest and growing number of applications of this material.
In this doctoral thesis, a direct and rationale approach to predict the tensile response of SFRC for structural design calculations is developed. While insight on the material behavior is firstly gained through an experimental investigation, the formulation of the new constitutive model follows a bottomup approach: it fragments the material's behavior into levels of smaller complexity and then models each of them until the overall behavior can be explained.
The dissertation is subdivided into five main parts: I) The motivations for this research project are pointed out. II) Uniaxial tensile test results are obtained to understand the major mechanisms governing the post-cracking strength. III) Two models predicting the pullout responses of inclined steel fibers are developed, covering straight and hooked fibers. IV) The orientation of fibers is investigated in detail at the single fiber level through statistical analyses. Then, practical aspects associated to the manufacturing process are integrated within a novel framework to predict fiber orientation. V) Based on Parts III-IV, the new constitutive model is formulated and validated with experimental results from Part II. Further insight on the tensile behavior is gained through a parametric study and Engineered Expressions for Design and Optimization (EEDO) are proposed.
The proposed design-oriented constitutive model differentiates itself from previous studies in multiple aspects and defines a new philosophy for the design of SFRC elements. This model provides a direct and practical procedure to obtain the material's tensile behavior by means of parameters with physical meaning and based on clear concepts: fiber pullouts and orientations.
One of the major contributions of this work is the ability to predict the stress-crack width curves that reflect the specific combination of the properties of the matrix and fibers applied. Furthermore, it introduces a novel philosophy for the material design regarding that the influences of the production process, fresh-state properties and the element to be built are taken into account to define the constitutive diagram.
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Abou-Elfath, Hamdy Mohamed. "Rehabilitation of nonductile reinforced concrete buildings using steel systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0025/NQ51170.pdf.
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Zhou, Wenxing. "Reliability evaluations of reinforced concrete columns and steel frames." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58250.pdf.
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Abou-Elfath, Hamdy Mohamed. "Rehabilitation of nonductile reinforced concrete buildings using steel systems /." *McMaster only, 1998.
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Ting, Arthur Kung Kii. "Time Equivalent for Protected Steel and Reinforced Concrete Structures." Thesis, University of Canterbury. Civil Engineering, 1999. http://hdl.handle.net/10092/8296.
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This report aims to evaluate the reliability of the formulae commonly used to determine the severity of a compartment fire. It briefly explains the concept behind fire resistance rating for structural elements, describing how the severity of a 'real' compartment fire is equated to that of the 'standard' fire used in laboratories for fire resistance testing. This is followed by a discussion of the computer method used in this report in dissecting those formulae and the development of some computer techniques for calculating fire severity.
Apart from that, various physical parameters of a compartment such as the opening sizes are looked at to determine the significance of their influence on the fire severity.
This report also goes beyond the works carried out in the past and examines the validity of the formulae for scenarios that have not previously been considered and explores the validity of the calculation methods intended for steel member for reinforced concrete structure. Finally some discussions and conclusions are made from the findings.
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Oikonomou-Mpegetis, Sotirios. "Behaviour and design of steel fibre reinforced concrete slabs." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23792.
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Using Steel Fibre Reinforced Concrete (SFRC) can bring substantial benefits to the construction industry of which savings in construction time and labour are most significant. In addition, steel fibres enhance crack control particularly when acting in conjunction with reinforcement bars. Despite the aforementioned benefits of SFRC, there is a still a lack of consensus on the principles that should be adopted in its design. Currently, a number of different test methods are used to determine the material properties of SFRC but there is no agreement on which method is best. As a result, steel fibre suppliers claim widely differing properties for similar fibres which leads to confusion amongst designers and in some cases inadequate structural performance. This research considers the design of SFRC slabs with emphasis on pile supported slabs which are frequently designed using proprietary methods due to the absence of codified guidance. Key issues in the design of such slabs are control of cracking in service and the calculation of flexural and punching shear resistances. A fundamental challenge is that SFRC exhibits a strain softening response at the dosages commonly used in slabs. At present, the yield line method is generally considered most suitable for designing such slabs at the ultimate limit state but there is a lack of consensus on the design moment of resistance as the bending moment along the yield lines reduces with increasing crack width. This thesis investigates these matters using a combination of experimental and theoretical work. The experimental work compares material properties derived from notched beam and round plate tests and seeks to determine a relationship between the two. Tests were also carried out on continuous slabs with the same material properties as used in the notched beam and round plate tests. Round plate tests were also carried out to determine the contribution of steel fibres to punching shear resistance. The theoretical work investigates the applicability of yield line analysis to the design of SFRC slabs using a combination of numerical modelling and design oriented analytical models. Design for punching shear and the serviceability limit state of cracking are also considered.
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Mouton, Christiaan Johannes. "Investigating the tensile creep of steel fibre reinforced concrete." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20355.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Research in concrete has advanced to such an extent that it is now possible to add steel fibres to concrete in order to improve its durability and ductility. This led to a research group in Europe, FIB, who has provided guidelines to designing Steel Fibre Reinforced Concrete (SFRC) structures. They have found that it is possible for SFRC beams in flexure to be in static equilibrium. However, the time-dependent behaviour of SFRC has not been researched fully and it requires further investigation. When looking at a concrete beam in flexure there are two main stress zones, the compression zone and the tension zone, of which the tensile zone will be of great interest. This study will report on the investigation of the tensile time-dependent behaviour of SFRC in order to determine how it differs from conventional concrete. The concrete has been designed specifically to exhibit strain-softening behaviour so that the material properties of SFRC could be investigated fully. Factors such as shrinkage and tensile creep of SFRC were of the greatest importance and an experimental test setup was designed in order to test the tensile creep of concrete in a simple and effective manner. Comparisons were be made between the tensile creep behaviour of conventional concrete and SFRC where emphasis was placed on the difference between SFRC specimens before and after cracking occurred in order to determine the influence of steel fibre pull-out. The addition of steel fibres significantly reduced the shrinkage and tensile creep of concrete when un-cracked. It was however found that the displacement of fibre pull-out completely overshadowed the tensile creep displacements of SFRC. It was necessary to investigate what effect this would have on the deflection of SFRC beams in flexure once cracked. Viscoelastic behaviour using Maxwell chains were used to model the behaviour of the tensile creep as found during the tests and the parameters of these models were used for further analyses. Finite Element Analyses were done on SFRC beams in flexure in order simulate creep behaviour of up to 30 years in order to determine the difference in deflections at mid-span between un-cracked and pre-cracked beams. The analyses done showed that the deflections of the pre-cracked SFRC beams surpassed the requirements of the Serviceability Limit States, which should be taken into account when designing SFRC beams.
AFRIKAANSE OPSOMMING: Die navorsing in beton het gevorder tot so ‘n mate dat dit nou al moontlik is om staal vesels by die beton te voeg sodat dit beton se duursaamheid en duktiliteit te verbeter. Dit het gelei tot ‘n groep in Europa, FIB, wat dit moontlik gemaak het om Staal Vesel Beton (SVB) strukture te ontwerp. Hulle het gevind dat dit moontlik is vir SVB balke om in statiese ewewig te wees tydens buiging. Die tyd afhanklike gedrag van SVB is egter nog nie deeglik ondersoek nie en benodig dus verdure ondersoek. Wanneer ‘n balk in buiging aanskou word kan twee hoof spanningzones identifiseer word, ‘n druk zone en ‘n trek zone, waarvan die trek zone van die grootste belang is. Hierdie studie gaan verslag lewer oor die ondersoek van tyd-afhanklike trekgedrag van SVB om te bepaal hoe dit verskil van konvensionele beton. Die beton was spesifiek ontwerp om vervormingsversagtende gedrag te wat maak dat die materiaal eienskappe van SVB ten volle ondersoek kan word. Faktore soos krimp en die trekkruip van SVB was van die grootste belang en ‘n eksperimentele toets opstelling was ontwerp om die trekkruip van beton op ‘n eenvoudige en effektiewe manier te toets. Daar was vergelykings getref tussen die trekkruip gedrag van konvensionele beton en SVP en groot klem was geplaas op die verskil tussen SVB monsters voor en na die monsters gekraak het om te bepaal wat die invloed was van staalvesels wat uittrek. Die byvoeging van staalvesels het beduidend die kruip en trekkruip van beton verminder. Daar was alhoewel gevind dat die verplasing van die uittrek van staalvesels heeltemal die trekkruip verplasings van SVB oorskadu het. Dit was nodig om te sien watse effek dit op die verplasing van SVB balke in buiging sal hê. Viskoelastiese gedrag deur Maxwell kettings was gebruik om die gedrag van trekkruip, soos gevind deur die toetse, te modelleer en die parameters van hierdie modelle was verder gebruik vir analises. Eindige Element Analises was gedoen op SVB balke in buiging om die trekkruip gedrag tot op 30 jaar te simuleer op die verskil tussen die defleksies by midspan tussen ongekraakte en vooraf gekraakte balke te vind. Die analises het gewys dat die defleksies van die vooraf gekraakte balke nie voldoen het aan die vereistes van die Diensbaarheid limiete nie, wat in ag geneem moet word wanneer SVB balke ontwerp word.
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Paine, Kevin Andrew. "Steel fibre reinforced concrete for prestressed hollow core slabs." Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/11095/.
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An investigation of prestressed concrete containing steel fibres as secondary reinforcement to improve performance in shear, flexure and bond is reported. Emphasis is placed on the use of steel fibres in prestresssed extruded hollow core slabs, since these common precast elements have intrinsic difficulty in incorporating traditional secondary reinforcement due to their unique shape and manufacturing method. Two separate studies were carried out. The first study involved laboratory investigations into the bond between fibre reinforced concrete (FRC) and the prestressing strand, and the shear behaviour of laboratory-cast prestressed fibre reinforced concrete (PFRC) beams. The second part involved the factory production of fibre reinforced hollow core slabs in co-operation with a local manufacturer. The fibre reinforced hollow core slabs were subjected to conventional full-width shear tests, concentrated load shear tests, and to transverse flexure. For all laboratory cast elements, cubes, cylinders and prisms were cast to investigate compressive, tensile and flexural properties, respectively. Two types of steel fibre were investigated: hooked-end steel fibres at fibre volume fractions (Vf) of 0.5%, 1.0% and 1.5%; and amorphous metal fibres at Vf‘s of 0.28% and 0.56%. The trial production of fibre reinforced hollow core slabs necessitated the investigation of the effect of steel fibres on the extrusion manufacturing process. It was shown that fibre reinforced hollow core slabs could be adequately compacted with only slight increases in mixing water. Fibres were found to distribute randomly throughout the cross-section. However, the rotation of the augers affected the orientation of fibres, with fibres tending to align vertically in the web. It was shown that the addition of steel fibres to prestressed concrete has a negative effect on the bond between matrix and tendon, leading to longer transfer lengths. The effect of the increase in transfer length was to reduce cracking shear strengths by 4%. Shear tests showed that the incorporation of steel fibres could increase shear strength by as much as 45% for Vf = 1.5%. This increase in shear strength, known as the fibre contribution, was shown to be due to fibres bridging across the crack and an increased compressive resistance due to fibres arresting the propagation of cracks into the compressive zone. A semi-empirical equation for shear strength of PFRC elements is developed. It is given in two forms, one compatible with the present equations for prestressed concrete given in BS 8110 and Eurocode 2, and a second form compatible with that advocated for fibres in reinforced concrete. The equation makes use of equivalent flexural strength which is recognised as the most useful material property for design of FRC. The equation was found to give good correlation with the shear strength of single web beams cast both in the laboratory and under factory conditions. However, a overall strength reduction factor is required for full-width hollow core slabs to account for uneven load distribution and inconsistent web widths. This is consistent with tests on plain hollow core slabs found in the literature.
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BRODOWSKI, DAVID MICHAEL. "APPLICATION OF STEEL FIBER REINFORCED CONCRETE TO BURIED STRUCTURES." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1123510082.
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Kölle, Boris. "Behaviour of steel fibre reinforced high performance concrete under biaxial loading conditions." Connect to e-thesis, 2006. http://theses.gla.ac.uk/715/.
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Thesis (Ph.D.) - University of Glasgow, 2006.Ph.D. thesis submitted to the Department of Civil Engineering, University of Glasgow, 2006. Includes bibliographical references. Print version also available.
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Thorburn, Lorna Jane. "A study of externally reinforced fibre-reinforced concrete bridge decks on steel girders." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0028/NQ31536.pdf.
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Chen, Liquan. "Steel corrosion sensing and chloride control in concrete structures /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202008%20CHEN.
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Goodfellow, Roderick Gerald Charles. "Ductility of reinforced concrete flexural members constructed from high performance steel and concrete." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/7645.
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Ozcelik, Ramazan. "Seismic Upgrading Of Reinforced Concrete Frames With Structural Steel Elements." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613450/index.pdf.
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This thesis examines the seismic internal retrofitting of existing deficient reinforced concrete
(RC) structures by using structural steel members. Both experimental and numerical studies
were performed. The strengthening methods utilized with the scope of this work are chevron
braces, internal steel frames (ISFs), X-braces and column with shear plate. For this purpose,
thirteen strengthened and two as built reference one bay one story portal frame specimens
having 1/3 scales were tested under constant gravity load and increasing cyclic lateral
displacement excursions. In addition, two ½scaled three bay-two story frame specimens strengthened with chevron brace and ISF were tested by employing continuous pseudo dynamic testing methods. The test results indicated that the cyclic performance of the Xbrace and column with shear plate assemblage technique were unsatisfactory. On the other hand, both chevron brace and ISF had acceptable cyclic performance and these two techniques were found to be candidate solutions for seismic retrofitting of deficient RC structures. The numerical simulations by conducting nonlinear static and dynamic analysis were used to estimate performance limits of the RC frame and steel members. Suggested strengthening approaches, chevron brace and ISF, were also employed to an existing five story case study RC building to demonstrate the performance efficiency. Finally, design approaches by using existing strengthening guidelines in Turkish Earthquake Code and ASCE/SEI 41 (2007) documents were suggested.
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Cohen, Michael I. "Structural Behaviour of Self Consolidating Steel Fiber Reinforced Concrete Beams." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23101.
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When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.
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Ulbinas, Darius. "Cracking and stiffness analysis of steel fiber reinforced concrete members." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130211_185704-20674.
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In last decades, fibre reinforcement is widely used in many countries as ad-ditive for concrete and cement mortar mixture for production of structures. Fibre reinforcement applications in Lithuania are often restricted to production of concrete floor for different purposes. Whereas, in other countries (USA, Japan, Germany and other) application area of fibre reinforcement is much wider, for example: bridge deck, thin-walled structures for special constructions (tunnels, reservoirs, etc), covering of roadway, airport landing strip, pipelines, pile foundation. Application of fibre reinforcement is considered as one of the most important development area of structural construction in the world.
Fibre reinforcement significantly improves service properties of concrete. Fibre reinforcement does not have considerable influence on concrete compressive strength, however it significantly changes fracture characteristics of tensile concrete. Fracture of non-reinforced tensile concrete is brittle, whereas with fibre reinforcement–plastic. This is due to restraining of tensile deformations by distributed fibres. Fibre reinforcement influence on concrete member is more effective than bar reinforcement, as tensile deformations are restrained in the whole volume of tensile zone. Whereas, tensile deformations in a RC member are restrained in the specific interaction area of reinforcement and concrete. Main advantages of fibre reinforcement are slow crack propagation, greater tensile and... [to full text]Jau kelis dešimtmečius plieno plaušas visame pasaulyje plačiai taikomas kaip priedas betono ir cementinio skiedinio mišiniams, naudojamiems statybinių konstrukcijų gamybai. Lietuvoje dispersinis armavimas dažniausiai naudojamas betonuojant įvairios paskirties pastatų grindis. Tuo tarpu, kitose pasaulio šalyse (JAV, Japonijoje, Vokietijoje ir kt.) dispersinė armatūra naudojama daug plačiau, pvz.: tiltų perdangoms, plonasienėms specialiųjų statinių (tunelių, rezervuarų ir t. t.) konstrukcijoms, kelių dangoms, oro uostų pakilimo takams, vamzdynams, poliniams pamatams ir t. t. Dispersinės armatūros taikymas visame pasaulyje laikoma viena iš prioritetinių statybinių konstrukcijų vystymosi sričių. Dispersinis armavimas neturi didesnės įtakos gniuždomajam betono stipriui, tačiau lemia visiškai skirtingą tempiamojo betono suirimo pobūdį. Nearmuoto tempiamojo betono suirimas yra trapus, tuo tarpu dispersiškai armuoto – plastinis. Tai lemia dispersiškai pasiskirsčiusio plaušo sukeliamas tempimo deformacijų suvaržymas. Dispersinio armavimo poveikis betoniniam elementui yra daug efektyvesnis nei strypinės armatūros, kadangi tempimo deformacijos varžomos visame tempiamosios zonos tūryje. Tuo tarpu klasikiniame gelžbetoniniame elemente tempimo deformacijos varžomos tik tam tikrame armatūros ir betono sąveikos plote. Lėtesnis plyšių vystymasis, didesnis atsparumas smūgiams ir nuovargiui bei plastiškumas yra pagrindiniai veiksniai, lemiantys dispersiškai armuotų gelžbetoninių konstrukcijų... [toliau žr. visą tekstą]
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Kalman, Deidra. "Use of steel fiber reinforced concrete for blast resistant design." Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4027.
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Smith, Joel Aaron. "Implosion of steel fibre reinforced concrete cylinders under hydrostatic pressure." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ45939.pdf.
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Tupper, Bryce. "Seismic response of reinforced concrete walls with steel boundary elements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0023/MQ50667.pdf.
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Wang, Chuanbo. "Experimental investigation on behavior of steel fiber reinforced concrete (SFRC)." Thesis, University of Canterbury. Civil Engineering, 2006. http://hdl.handle.net/10092/1155.
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During the last four decades, fiber reinforced concrete has been increasingly used in structural applications. It is generally accepted that addition of steel fibers significantly increases tensile toughness and ductility, also slightly enhances the compressive strength. Although several studies have reported previously the favorable attributes of steel fiber reinforced concrete (SFRC), little general data is related to performance modeling. There are studies on the effect of fibers on compression, tension and shear behavior of concrete. As models proposed so far can, at best, describe only a few aspect of SFRC with a given type and amount of fibers, establishing simple and accurate generalized equations to describe the behavior of SFRC in tension, compression and shear that take into account the fiber type and content is essential. Therefore, a comprehensive experimental research on SFRC is conducted in University of Canterbury to develop generalized equations to represent the characteristics of SFRC. In this research, standard material tests of SFRC are carried out in tension, compression and shear to enable the parametric characterization and modeling of SFRC to be conducted. The tests are conducted using two different propriety fiber types (NovotexTM and DramixTM) with volumetric ratios ranging from 0 to 2 percent of the Novotex fibers and with 1 percent Dramix fibers. Compression tests are conducted on small and large cylinders. For characterization of tensile behavior, several different test methods are used including: direct tension of SFRC alone; SFRC with tension applied to an embedded longitudinal rebar; and flexural bending test. Similarly direct shear tests are conducted to investigate the additional shear resistance contributed by steel fibers. Variations in the results of different specimens are reconciled through normalization of stress and strain parameters. Based on the experimental results, empirical relations are derived for modeling and analysis of SFRC.
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Haji-Kazemi, H. "Behaviour of reinforced concrete beams with externally attached steel plates." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377127.
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Tehrani, Fariborz Mohammadi. "Performance of steel fiber-reinforced concrete in beam-column connections." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1619097981&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Johnson, Jalen Gerreld. "Blast Performance of Hybrid GFRP and Steel Reinforced Concrete Beams." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99085.
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The threat of terrorist bombings and accidental industrial explosions motivates the need for more economical and efficient blast-resistant construction techniques that offer enhanced levels of protection at reduced component damage levels. Despite having a high strength-to-weight ratio and being chemically inert, fiber reinforced polymer (FRP) reinforcing bars are not currently used in blast-resistant reinforced concrete due to their brittle nature and lack of ductility. However, the innovative use of blended mixtures of FRP and steel rebar as tensile reinforcement promises to address these limitations through self-centering behavior that provides reductions in residual damage and enhancements in flexural performance. This thesis presents the results of an experimental and analytical investigation on the effect of hybrid arrangements of glass fiber reinforced polymer (GFRP) and conventional mild steel reinforcement on the blast performance of reinforced concrete beams.
Seven large-scale reinforced concrete beams with different combinations of tensile steel and GFRP rebar were designed, constructed, and tested under progressively increasing blast loading generated using the Virginia Tech Shock Tube Research Facility. The effect of hybrid reinforcing on the blast performance of the beams was evaluated based on the global response, failure mode, damage pattern, mid-span displacement, and support reactions of the tested beams. The results demonstrated several benefits in using hybrid arrangements of steel and GFRP reinforcement. Beams with hybrid reinforcing experienced reduced overall residual displacements compared with similar conventionally reinforced concrete members. This was attributed to the elastic nature of GFRP rebar which was found to produce a self-centering behavior that assisted in returning the hybrid members to their original undeformed position. This permitted the hybrid beams to safely experience larger maximum displacements at substantially less damage than all-steel construction. Furthermore, if the GFRP reinforcement did rupture, the presence of steel arrested hazardous component failure and provided additional energy dissipation and redundancy. Accompanying the experimental tests was an inelastic single-degree-of-freedom analysis to predict the displacement time-history response of the beams. Reasonably good predictions of response were obtained when the advanced material models and the effects of accumulated damage due to repeated blast testing were incorporated into the analytical predictions. Finally, a series of protective design recommendations and a new proposed response limit, that describes the level of damage achieved after a blast event, were established to encourage use of hybrid GFRP/steel reinforcement in blast-resistant construction.Master of Science
The threat of terrorist bombings and accidental industrial explosions motivate the need for new blast resistant construction techniques. Despite having a high strength-to-weight ratio and being chemically inert, fiber reinforced polymer (FRP) reinforcing bars are not currently used in blast-resistant reinforced concrete due to their brittle nature and lack of ductility. However, the innovative use of blended mixtures of FRP and steel rebar as tensile reinforcement promises to address these limitations through self-centering behavior that provides reductions in residual damage and enhancements in flexural performance. Large-scale reinforced concrete beams with different combinations of steel and GFRP rebar were designed, constructed, and tested under progressively increasing blast loads, gen-erated by the Virginia Tech Shock Tube Research Facility. The results demonstrated that beams with hybrid reinforcing experienced reduced overall residual damage in comparison with similar conventionally reinforced concrete members. Additionally, if the GFRP rebar ruptured, the presence of steel prevented a brittle failure and provided additional energy dissipation and redundancy. The inelastic single degree of freedom model developed for this investigation resulted in an adequate prediction of the load-deflection characteristics record-ed from experimental testing. To encourage the use of hybrid FRP/steel reinforcement in blast-resistant construction, a series of protective design recommendations and a proposed response limit, that describes the level of damage achieved after a given blast event, were established.
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Rupp, John F. "MODELING OF STEEL-JACKETED REINFORCED CONCRETE UNDER AXIAL COMPRESSIVE LOADS." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330615432.
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García, Taengua Emilio José. "Bond of Reinforcing Bars to Steel Fiber Reinforced Concrete (SFRC)." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/32952.
Full textAbstract:
The use of steel fiber reinforced concrete (SFRC hereafter) is becoming more and more
common. Building codes and recommendations are gradually including the positive effect of
fibers on mechanical properties of concrete. How to take advantage of the higher ductility
and energy absorption capacity of SFRC to reduce anchorage lengths when using fibers is
not a straightforward issue.
Fibers improve bond performance because they confine reinforcement (playing a similar
role to that of transverse reinforcement). Their impact on bond performance of concrete is
really important in terms of toughness/ductility.
The study of previous literature has revealed important points of ongoing discussion
regarding different issues, especially the following: a) whether the effect of fibers on bond
strength is negligible or not, b) whether the effect of fibers on bond strength is dependent
on any other factors such as concrete compressive strength or concrete cover, c)
quantifying the effect of fibers on the ductility of bond failure (bond toughness). These
issues have defined the objectives of this thesis.
A modified version of the Pull Out Test (POT hereafter) has been selected as the most
appropriate test for the purposes of this research. The effect of a number of factors on bond
stress¿slip curves has been analyzed. The factors considered are: concrete compressive
strength (between 30 MPa and 50 MPa), rebar diameter (between 8 mm and 20 mm),
concrete cover (between 30 mm and 5 times rebar diameter), fiber content (up to 70
kg/m3), and fiber slenderness and length.
The experimental program has been designed relying on the principles of statistical Design
Of Experiments. This has allowed to select a reduced number of combinations to be tested
without any bias or loss of accuracy. A total of 81 POT specimens have been produced and
tested.
An accurate model for predicting the mode of bond failure has been developed. It relates
splitting probability to the factors considered. It has been proved that increasing fiber
content restrains the risk of splitting failure. The favorable effect of fibers when preventing
splitting failures has been revealed to be more important for higher concrete compressive
strength values. Higher compressive strength values require higher concrete
cover/diameter ratios for splitting failure to be prevented. Fiber slenderness and fiber
length modify the effect of fiber content on splitting probability and therefore on minimum
cover/diameter ratios required to prevent splitting failures. Two charts have been
developed for estimating the minimum cover/ diameter ratio required to prevent splitting.
Predictive equations have been obtained for estimating bond strength and areas under the
bond stress¿slip curve as a function of the factors considered. Increasing fiber content has a
slightly positive impact on bond strength, which is mainly determined by concrete
compressive strength. On the contrary, fibers have a very important effect on the ductility of
bond failure, just as well as concrete cover, as long as no splitting occurs.
Multivariate analysis has proved that bond stress corresponding to the onset of slippage
behaves independently from the rest of the bond stress¿slip curve. The effect of fibers and
concrete compressive strength on bond stress values corresponding to the onset of slips is
mainly attributable to their influence on the material mechanical properties. On the
contrary, the effect of fibers and concrete cover on the rest of the bond stress¿slip curve is
due to their structural role.García Taengua, EJ. (2013). Bond of Reinforcing Bars to Steel Fiber Reinforced Concrete (SFRC) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/32952
TESIS
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Trezona, James Richard. "Analysis and design of circular reinforced concrete columns and concrete filled steel tube columns /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09ENS/09enst818.pdf.
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Zioris, Stavros, and Alija Vranjkovina. "Evaluation of a Tramway’s Track Slab in Conventionally Reinforced Concrete or Steel Fibre Concrete." Thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177890.
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The dominant reinforcement used widely for concrete structures is conventional steel bars (rebars). Nevertheless, the perpetual effort toward evolution and development could not exclude the engineering field, thus new innovative and sophisticated methods are introduced. It is true that, due to lack of extended regulations and standards, the fibre reinforced concrete (FRC) was limited to non-structural applications. However, the last years the situation is changing rapidly and already the applications of FRC include actual structural members. The subject of the current thesis was a tramway’s track slab from “Sparvag City” project in Stockholm. The aim was to evaluate the track slab, in terms of alternative reinforcing ways. In particular three models were examined; model I – conventional reinforcement, model II – steel fibre reinforced concrete (SFRC) and model III – SFRC with conventional reinforcement. The assessment was performed from structural, regulations – compliance, economic and ergonomic perspective. A static linear analysis of the track slab was performed using Abaqus; a finite element analysis (FEA) software. The track slab was subjected only to mechanical loads (selfweight and traffic actions) and thus, the design internal forces were extracted. Thereafter, Eurocode 2 (EN 1992-1-1, 2004) and Swedish standards for FRC structures (SS 812310:2014) were utilized for the reinforcement design of the models. The design was performed in ultimate limit state (ULS), for bending moment and shear resistance, and in serviceability limit state (SLS), for stress limitation and crack control. Model I and III were successfully designed abiding with the respective regulations and requirements, while “only fibres” model was considered valid only for bending moment resistance according to SS 812310:2014. Consequently only models I and III were compared with each other. From the economic comparison it was obtained that model I was less expensive than model III, but on the other hand its construction time was larger. Furthermore model III contained significantly less total rebars’ mass in comparison to model I. This particularity was crucial for the ergonomic assessment. The human factors, that were relevant to the ergonomic assessment, improved the quality of the comparison and the extracted inferences, but also introduced aspects impossible to be put against economic facts as an equal quantity. Thus, there was not a final proposal as the best solution for the thesis subject.Armeringen av betongkonstruktioner domineras av konventionell armering (armeringsjärn). Med den ständiga strävan mot utveckling och förbättring har inom teknikområdet nya innovativa och avancerade metoder introducerats. Det är på grund av bristen på normer, standarder som fiberarmerad betong begränsats till icke- bärande ändamål. Däremot har situationen förändrats under de senaste åren, redan idag kan man se konstruktioner där fiberarmering används till bärande ändamål. Amnet for den aktuella masterexamen var betongplatta i projektet ”Sparvag City” i Stockholm. Syftet var att utvärdera betongplattan, i form av att undersöka alternativa armeringsmöjligheter. I synnerhet undersöktes tre modeller; modell I- konventionellt armerad platta, modell IIstålfiberarmerad platta och modell III stålfiberarmerad platta kombinerad med konventionell armering. Modellernas möjligheter att uppfylla regelverkens krav undersöktes, men de jämfördes även ur ekonomiskt samt ergonomiskt perspektiv. En statisk linjär analys av betongplattan genomfördes i ett finit element program, Abaqus. Betongplattan utsattes för mekanisk belastning (egenvikt samt trafiklast) för vilken dimensionerande krafter extraherats. Därefter användes Eurocode 2 (EN 1992-1-1, 2004) och den svenska standarden för fiberarmerade betong konstruktioner (SS 812310:2014) för vidare konstruktionsberäkningar. Konstruktionsberäkningarna för betongplattan genomfördes i brottgränstillstånd för böjmoment samt tvärkraft, i brukgränsmotståndet undersöktes betongplattan för spänningsbegränsningar samt sprickkontroll. Konstruktionsberäkningarna kunde genomföras för modell I och III med de existerande föreskrifterna och kraven, men modellen med ”endast fibrer” kunde endast dimensionerna för böjmoment enligt SS 812310:2014. Därför kunde endast modell I och III fortsättningsvis jämföras med varandra. Från den ekonomiska jämförelsen erhölls det att modellen I var billigare än modell III, men att konstruktionstiden var längre. Dessutom var behoven för konventionell armering (armeringsjärn) betydligt mindre för modell III till skillnad från modell I. Modellernas innehåll av konventionell armering var avgörande för den ergonomiska bedömningen. Den mänskliga faktorn, som var relevanta för den ergonomiska bedömningens, gav jämförelsen av modellerna en annan dimension, där de viktiga mänskliga faktorerna
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Ngo, Van Minh. "Localized failure for coupled thermo-mechanics problems : applications to steel, concrete and reinforced concrete." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00978452.
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During the last decades, the localized failure of massive structures under thermo-mechanical loads becomes the main interest in civil engineering due to a number of construction damaged and collapsed due to fire accident. Two central questions were carried out concerning the theoretical aspect and the solution aspect of the problem. In the theoretical aspect, the central problem is to introduce a thermo-mechanical model capable of modeling the interaction between these two physical effects, especially in localized failure. Particularly, we have to find the answer to the question: how mechanical loading affect the temperature of the material and inversely, how thermal loading result in the mechanical response of the structure. This question becomes more difficult when considering the localized failure zone, where the classical continuum mechanics theory can not be applied due to the discontinuity in the displacement field and, as will be proved in this thesis, in the heat flow. In terms of solution aspect, as this multi-physical problem is mathematical represented by a differential system, it can not be solved by an 'exact' analytical solution and therefore, numerical approximation solution should be carried out. This thesis contributes in both two aspects. Particularly, thermomechanical models for both steel and concrete (the two most important materials in civil engineering), which capable of controling the hardening behavior due to plasticity and/or damage and also the softening behavior due to the localized failure, are carried out and discussed. Then, the thermomechanical problems are solved by 'adiabatic' operator split procedure, which 'separates' the multi-physical process into the 'mechanical' part and the 'thermal' part. Each part is solved individually by another operator split procedure in the frame-work of embbed-discontinuity finite element method. In which, the 'local' discontinuities of the displacement field and the heat flow is solved in the element level, for each element where localized failure is detected. Then, these discontinuities are brought into the 'static condensation' form of the overall equilibrium equation, which is used to solved the displacement field and the temperature field of the structure at the global level. The thesis also contributes to determine the ultimate response of a reinforced concrete frame submitted to fire loading. In which, we take into account not only the degradation of material properties due to temperature but also the thermal effect in identifying the total response of the structure. Moreover, in the proposed method, the shear failure is also considered along with the bending failure in forming the overal failure of the reinforced structure. The thesis can also be extended and completed to solve the behavior of reinforced concrete in 2D or 3D case considering the behavior bond interface or to take into account other type of failures in material such as fatigue or buckling. The proposed models can also be improved to determine the dynamic response of the structure when subjected to earthquake and/or impact.
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Gravina, Rebecca Jane. "Non-linear overload behaviour and ductility of reinforced concrete flexural members containing 500MPa grade steel reinforcement." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phg777.pdf.
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Includes corrigenda (inserted at front) and list of publications published as a result of this research. Includes bibliographical references (leaves 192-199) Investigates the overload behaviour and modes of collapse of reinforced concrete flexural members containing 500MPa grade reinforcing steel and evaluates the adequacy of current ductility requirements for design according to AS 3600 to ensure strength and safety.
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Almahmood, Hanady, Ashraf F. Ashour, and Therese Sheehan. "Flexural behaviour of hybrid steel-GFRP reinforced concrete continuous T-beams." Elsevier, 2020. http://hdl.handle.net/10454/17994.
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YesThis paper presents test results of six full scale reinforced concrete continuous T beams. One beam was reinforced with glass fibre reinforced polymer (GFRP) bars while the other five beams were reinforced with a different combination of GFRP and steel bars. The ratio of GFRP to steel reinforcement at both mid-span and middle-support sections was the main parameter investigated. The results showed that adding steel reinforcement to GFRP reinforced concrete T-beams improves the flexural stiffness, ductility and serviceability in terms of crack width and deflection control. However, the moment redistribution at failure was limited because of the early yielding of steel reinforcement at a beam section that does not reach its moment capacity and could still carry more loads due to the presence of FRP reinforcement. The experimental results were compared with the ultimate moment prediction of ACI 440.2R-17, and with the existing theoretical equations for deflection prediction. It was found that the ACI 440.2R-17 reasonably estimated the moment capacity of both mid-span and middle support sections. Conversely, the available theoretical deflection models underestimated the deflection of hybrid reinforced concrete T-beams at all load stages.
The full-text of this article will be released for public view after the publisher embargo on 10 Aug 2021.
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Mbewe, Peter Binali Kamowa. "Development of analytical flexural models for steel fibre-reinforced concrete beams with and without steel bars." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18088.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: There is an increasing demand for the development and use of innovative materials with reduced cost of construction while offering improved structural properties. Steel fibre reinforced concrete (SFRC) can be used as a structural material to substitute the conventional reinforcing bars partially or fully. However, there is little or no codified approach on the design procedures for SFRC members in the latest guidelines outlined in the draft 2010 Model code. It is against this background that analytical methods are derived in this study for the determination of the flexural capacity of strain-softening, deflection-hardening SFRC with and without steel reinforcing bars. Models used for the determination of the flexural capacity of SFRC rectangular sections are based on equivalent stress blocks for both compression and tensile stresses. These are derived from an elastic-perfect plastic model for compression and either an elastic-constant post-peak response or Rilem’s multi-linear model for tension, in which strain compatibility and force equilibrium theories are used. By employing the equivalent stress blocks for both tensile and compressive stress states, parameters are defined by converting the actual stress-strain distribution to an equivalent stress block, depending on the ratio of yield (or cracking) strain and post-yield (post-cracking) strains. Due to the simplicity of a drop-down tensile model and a bilinear compression model, these material models are used for the subsequent derivation of the flexural models for both SFRC with and without steel reinforcing bars. An experimental program is designed and executed for model verification. This includes material characterisation experiments for the determination of material model input parameters, and main beam flexural experiments for the determination of the beam bending capacity. An indirect tensile test is used for the characterisation of the tensile behaviour while a four-point bending test is used for beam bending behaviour. Both flexural models for SFRC with and without reinforcing bars have been verified to fairly predict the flexural capacity of the beams. However, the flexural model for SFRC with steel bars offers some challenges as to whether the synergetic effect of using both steel bars and steel fibres should be incorporated at the low fibre volumes as used in the verification exercise. Furthermore, the use of indirect methods to characterise tensile behaviour added some uncertainties in the material model parameters and hence may have affected the predictability of the model. More research on the verification of the models is required to enable the use of a wider concrete strength spectrum for the verification and possible modification of the models. Studies on the model uncertainty may also help determine the reliable safety factor for the use of the model in predicting design strength of beam sections at a prescribed reliability index.
AFRIKAANSE OPSOMMING: Daar is ‘n groeiende aanvraag na die ontwikkeling en gebruik van innoverende materiale met verminderde konstruksiekoste maar verbeterde strukturele eienskappe. Staalvesel-gewapende beton (SVGB) kan gebruik word as strukturele materiaal om die konvensionele wapeningstawe gedeeltelik of ten volle te vervang. Daar is egter min of geen gekodifiseerde benaderings tot die ontwerpprosedures vir SVGB-dele in die nuutste riglyne uitgestippel in die konsepweergawe van die 2010 Modelkode nie. Dit is teen hierdie agtergrond dat in hierdie studie analitiese metodes afgelei is vir die bepaling van die buigkapasiteit van spanning-versagtende, defleksie-verhardende SVGB met en sonder staalbewapeningstawe. Modelle wat gebruik is vir die bepaling van die buigkapasiteit van SVGB reghoekige snitte is gebaseer op ekwivalente spanningsblokke vir beide druk- en trekspannings. Hierdie is afgelei van ‘n elasties-perfekte plastiese model vir druk en óf ‘n elasties-konstante post-piek respons óf Rilem se multi-lineêre model vir spanning, waarin teorieë vir drukkapasiteit en krag-ewewig gebruik is. Deur die ekwivalente spanningsblokke vir beide trek- en drukspanningstoestande te implementeer, is parameters bepaal deur die werklike verspreiding van spanningsdruk om te wissel na ‘n ekwivalente spanningsblok, afhangend van die verhouding van swig- (of kraak-)spanning en post-swig (post-kraak) spannings. Te wyte aan die eenvoud van ‘n aftrek trekmodel en ‘n bilineêre kompressiemodel, is hierdie materiaalmodelle gebruik vir die daaropvolgende afleiding van die buigingsmodelle vir beide SVGB met en sonder staalbewapeningstawe. ‘n Eksperimentele program vir modelkontrolering is ontwerp en uitgevoer. Dit sluit eksperimente in vir materiaalbeskrywing, om invoerparameters van materiaalmodelle te bepaal, asook eksperimente vir hoofbalkbuigings, om balkbuigingskapasiteit te bepaal. ‘n Indirekte trektoets is gebruik vir die beskrywing van die trekgedrag, terwyl ‘n vierpuntbuigingstoets gebruik is vir balkbuiggedrag. Dit is bewys dat beide buigingsmodelle vir SVGB met en sonder staalbewapeningstawe die buigingskapasiteit van die balke redelik akkuraat kan voorspel. Nietemin, bied die buigingsmodel vir SVGB met staalbewapeningstawe sekere uitdagings: die vraag ontstaan rondom die insluiting van die sinergetiese effek van die gebruik van beide staalstawe en staalvesels met die lae veselvolumes soos gebruik in die kontroleringsoefening. Verder het die gebruik van indirekte metodes om die buigingsgedrag te bepaal, onsekerhede gevoeg by die materiaalmodelparameters en dit mag dus as sulks die voorspelbaarheid van die model beïnvloed. Meer navorsing moet uitgevoer word oor die kontrolering van die modelle sodat ‘n wyer spektrum van betonsterkte gebruik kan word vir die verifikasie en moontlike aanpassing van die modelle. Navorsing oor die wisselvalligheid van die modelle mag ook help om die betroubare veiligheidsfaktor te bepaal vir die model se gebruik in die berekening van ontwerpkrag van balkdele teen ‘n voorgeskrewe betroubaarheidsindeks.
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Young, Craig Steven. "The effects of end restraint on steel deck reinforced concrete floor systems /." This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-08182009-040222/.
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