Dissertations / Theses on the topic 'Steel-fibre reinforced concrete'
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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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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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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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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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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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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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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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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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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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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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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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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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Jarrat, Robert. "Construction in in-situ cast flat slabs using steel fibre reinforced concrete." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17861.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Fibre reinforced concrete (FRC) transforms concrete from a characteristically brittle material to one with a post-crack tensile residual capacity. Its application in industry has varied over the past of which the tensile properties have generally been used in the form of crack mitigation. More recently, the introduction of steel fibres has broadened this scope to structural applications in which the resisting tensile stresses that develop within a steel FRC (SFRC) element can be rather significant. This thesis reviews the existing practices and design models associated with SFRC and the suitability of its implementation as the sole form of reinforcement in in-situ cast flat slab systems. As a material SFRC is dependent on a number of factors which include the fibre type and volume, fibre distributions, element size, as well as the support and applied load conditions. Thus, its performance can be considered rather variable in comparison to conventional concrete should the incorrect practices be implemented. In order to adequately define the material characteristics, it is necessary to use test procedures that accurately reflect on the intended structural application. As a result a number of test procedures have been developed. In addition to this, the post-crack material performance is associated with a non-linear behaviour. This attribute makes the design of structural SFRC elements rather difficult. In an attempt to simplify this, existing design models define stress-strain or stress-crack width relations in which assumptions are made regarding the cross-sectional stress distribution at specified load states. This thesis takes on two parts in defining the suitability of SFRC as the sole form of reinforcement in flat slab systems. The first is a theoretical investigation regarding the micro and macro scale material performance of SFRC, the practices that exist in defining the material properties and its application in structural systems (particularly suspended slab systems), and a breakdown of the existing design models applicable to strain softening deflection hardening SFRC materials. The second part is an experimental program in which the fresh state and hardened state material properties of specified SFRC mix designs defined through flow and beam testing respectively. These properties are then implemented in the design and construction of full scale flexural and punching shear test slabs in an attempt to verify the theory applied. The investigation reveals that the use of SFRC significantly improves the ductility of concrete systems in the post-crack state through fibre crack bridging. This ductility can result in deflection hardening of flat slab systems in which the redistribution of stresses increases the load carrying capacity once cracking has taken place. However, the performance of large scale test specimens is significantly influenced by the construction practices implemented in which the material variability increases as a result of non-uniform fibre distributions. The results indicate that the load prediction models applied have potential to adequately predict the ultimate failure loads of SFRC flat slab systems but however cannot account for possible non-uniform fibre distributions which could result in premature failure of the system.
AFRIKAANSE OPSOMMING: Vesel versterkte beton (VVB) verander beton van die kenmerkende uiters bros material na ‘n material met ‘n residuele post-kraak trekkapasiteit. Die toepassing daarvan in die bedryf het in die verlede gewissel en die trek eienskappe is oor die algemeen gebruik vir kraak vermindering. Meer onlangs het die bekenstelling van staal vesel hierdie omvang verbreed na die strukturele toepassings waar trekspannings wat ‘n VVB element kan weerstaan noemenswaardig kan wees. Hierdie tesis ondersoek bestaande praktyke en ontwerpmodelle met die oog op staalvesel versterkte beton (SVVB) en die geskiktheid van die implementering daarvan as die enigste vorm van bekisting in in-situ gegiete plat blad stelsels. As ‘n materiaal, is SVVB afhanklik van ‘n aantal faktore wat die tipe vesel en volume, vesel verspreiding, element grootte, sowel as die randvoorwaardes tipe aangewende las insluit. As gevolg hiervan, kan die gedrag van SVVB, wat korrek geïmplimenteer word, as redelik varieerbaar beskou word wanneer dit met konvensionele beton vergelyk word. Ten einde die materiaaleienskappe voldoende te definieer, is dit noodsaaklik dat prosedures wat die strukturele toepassing akuraat voorstel, getoets word en daarom is ‘n aantal toets prosedures ontwikkel. Verder het die post-kraak materiaalgedrag ‘n nie-lineêre verband wat struktuurontwerp met SVVB redelik moeilik maak. Om dit te vereenvoudig, definieer bestaande ontwerpmodelle spanning-vervorming of spanning-kraakwydte verhoudings waarin aannames gemaak word ten opsigte van die spanningsverdeling oor ‘n snit, gegewe sekere lastoestande. Hierdie studie bestaan uit twee dele wat die geskiktheid van SVVB as die enigste vorm van bikisting in plat blad stelsels definieer. Die eerste deel bestaan uit ‘n teoretiese ondersoek wat handel oor die mikro- en makro-skaal materiaalgedrag van SVVB, die praktyke wat bestaan om die materiaaleienskappe en toepassing in strukturele sisteme (spesifiek opgelegde blad stelsels) te definieer, en ‘n uiteensetting van die bestaande ontwerpmodelle wat van toepassing is vir defleksie as gevolg van vervormingsversagting wat SVVB material verhard. Die tweede deel bestaan uit ‘n eksperimentele program waarin die materiaaleienskappe van gespesifiseerde SVVB meng-ontwerpe in die vars toestand en in die verharde toestand gedefinieer word deur middel van vloei- en balktoetse onderskeidelik. Hierdie eienskappe word dan toegepas vir die ontwerp en konstruksie van volskaalse buig- en ponsskuif toetsblaaie ten einde die modelle en teorie wat toegepas is, te bevestig. Die ondersoek toon dat die gebruik van SVVB die duktiliteit van beton sisteme noemenswaardig verbeter in die post-kraak toestand deur kraak oorbrugging. Hierdie duktiliteit kan defleksie verharding van plat blad stelsels veroorsaak waarin die herverdeling van spannings, nadat kraking plaasgevind het, die lasdraende kapasiteit verhoog. Die gedrag van die grootskaalse toetsmonsters word egter noemenswaardig beïnvloed deur die konstruksiemetodes wat geïmplementeer word waarin die materialveranderlikheid toeneem as ‘n gevolg van nie-uniforme vesel verdelings. Die resultate dui daarop dat die modelle wat toegepas is om die laste te voorspel, die potensiaal het om die grens falingslas van SVVB plat blad stelsel voldoende te voorspel, maar neem nie moontlike nie-uniforme veselverdelings wat kan lei tot vroeë faling van die stelsel in ag nie.
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Mondo, Eleonora. "Shear Capacity of Steel Fibre Reinforced Concrete Beams without Conventional Shear Reinforcement." Thesis, KTH, Bro- och stålbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41016.
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While the increase in shear strength of Steel Fibre Reinforced Concrete (SFRC) is well recognized, it has yet to be found common application of this material in building structures and there is no existing national standard that treats SFRC in a systematic manner. The aim of the diploma work is to investigate the shear strength of fibre reinforced concrete beams and the available test data and analyse the latter against the mostpromising equations available in the literature. The equations investigated are:Narayanan and Darwish’s formula, the German, the RILEM and the Italian guidelines. Thirty articles, selected among over one hundred articles taken from literature, have been used to create the database that contains almost 600 beams tested in shear. This large number of beams has been decreased to 371 excluding all those beams and test that do not fall within the limitation stated for this thesis. Narayanan and Darwish’s formula can be utilized every time that the fibre percentage, the type of fibres, the beam dimensions, the flexural reinforcement and the concrete strength class have been defined. On the opposite, the parameters introduced in the German, the RILEM and the Italian guidelines always require a further characterization of the concrete (with bending test) in order to describe the post‐cracking behaviour. The parameters involved in the guidelines are the residual flexural tensile strengths according to the different test set‐ups. A method for predicting the residual flexural tensile strength from the knowledge of the fibre properties, the cylindrical compressive strength of the concrete and the amount of fibres percentage is suggested. The predictions of the shear strength, obtained using the proposed method for the residual flexural tensile strength, showed to be satisfactory when compared with the experimental results. A comparison among the aforementioned equations corroborate the validity of the empirical formulations proposed by Narayanan and Darwish nevertheless only the other equations provide a realistic assessments of the strength, toughness and ductility of structural elements subjected to shear loading. Over the three investigated equations, which work with the post‐cracking characterization of the material, the Italian guideline proposal is the one that, due to its wide domain of validity and the results obtained for the gathered database of beams, has been selected as the most reliable equation.
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Kolle, Boris. "Behaviour of steel fibre reinforced high performance concrete under biaxial loading conditions." Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/715/.
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This thesis includes an experimental investigation of the behaviour of steel fibre reinforced high performance concrete (SFRHPC) under biaxial loading conditions. Also included are constitutive models to enable numerical predictions of the strength behaviour of such a material. Within the experimental stage a large biaxial test machine was designed and manufactured. The load capacity of each axis was 2000 kN. Special thought was given to the load platen system because of the friction which occurs between the platen system and the concrete specimen. Brush bearing platens and solid steel blocks with and without Teflon friction reducing pads were tried. Because the brush platen and the Teflon pads were constantly damaged during testing, solid steel block platens were finally used. For tests where tension loads were involved, experiments were carried out with dog-bone shaped specimens and specimens glued on to the platens. Finally, the tension loads were transferred through threaded rods cast into the specimens and connected to the machine patterns with screws. Modern control schemes and high speed data acquisition systems were used to monitor the material response and to collect experimental stress and strain results. The principal deformations were monitored and the crack patterns and failure modes examined. Failure envelopes were developed based on the strength data for each fibre variable. The load capacity of SFRHPC under biaxial load conditions was found to be larger than for plain HPC for all fibre types and volume fractions. The stress-strain recordings indicated a linear behaviour almost up to failure. The examined failure mode between plain and steel fibre HPC was similar and all specimens failed very suddenly with a splitting failure type. The test variables included four different types of hooked ended steel fibres with different fibre volume fractions from plain to 2% in 0.5% steps. The specimens were tested under the entire range of stress combinations including uniaxial compression and tension and biaxial compression-compression and compression-tension. As a result the specimen still failed in an explosive manner but the pieces were still connected together by fibres after failure. The biaxial strength compared to the uniaxial strength increased more, as observed with normal strength concrete. With the addition of fibres the biaxial strength behaviour of HPC was almost the same as for plain normal strength concrete. The deformation characteristics of plain and SFRHPC showed a linear behaviour up to a higher stress than normal strength concrete. In fact the linear limit was almost as high as the failure load. The examined strength data was used to model the biaxial strength envelopes of HPC and SFRHPC using different methods. These included the Ottosen failure criterion and the Willam and Warnke failure criterion.
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Graeff, Angela Gaio. "Long-term performance of recycled steel fibre reinforced concrete for pavement applications." Thesis, University of Sheffield, 2011. http://etheses.whiterose.ac.uk/14991/.
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Due to environmental concerns and increasing asphalt prices concrete pavements are seen as a sustainable alternative for road construction. Steel fibres are used as reinforcement for concrete pavements due to ease of construction, as well as improvement in the post-cracking, tensile/flexural and fatigue behaviour of the concrete. However, cost and method of construction are two major barriers for their use. Recycled fibres obtained from post-consumer tyres are a new alternative due to their lower cost and potential environmental benefits. The roller compacted concrete technique is also an alternative that enables road construction with the use of conventional asphalt equipment. These were the two main innovations being investigated by the FP6 EU Project Ecolanes. Understanding the durability of recycled steel fibre reinforced concrete (SFRC) is very important before these technologies can be used in real structures. This thesis addresses the issue of long-tenn behaviour of recycled SFRC, based on an experimental programme divided in two main studies: I) the mechanical properties (compressive and flexural behaviour), pore structure (porosity, density and free-shrinkage) and transport mechanisms (penneability, sorptivity and diffusivity) and 2) the main deterioration processes affecting the perfonnance of concrete pavements, corrosion (accelerated by means of wet-dry cycles in chloride solution), freeze-thaw (accelerated by continuous submerged freezing and thawing cycles) and fatigue (accelerated by flexural cyclic loads). A probabilistic analysis in terms of service life design has also been developed. Recycled fibres can increase the flexural strength of the concrete by up to 70% compared to plain concrete and they can significantly enhance the post-cracking behaviour. Recycled fibres, when added 2-6% by mass, do not affect the pore structure and the transport mechanisms of the concrete. Exceptions apply when contents around 6% by mass lead to compaction problems or affect the rheological properties of the concrete. Recycled fibres improve the fatigue resistance by allowing approximately 30% higher stresses than plain concrete for an endurance life of 2 million cycles. Fibres also contribute to slowing down the advanced stage of freeze-thaw degradation of concrete. Both fatigue and freeze-thaw are enhanced since these fibres control different stages of crack propagation. When subjected to wet-dry cycles, the fibres appear to be well protected inside the concrete and the main consequences are only in terms of superficial rust. The coupled benefits of mechanical and long-term performance of recycled SFRC make it a promising alternative for concrete pavements, especially in blends with industrially produced fibres. If these advantages are taken into account in the design of concrete pavements, a 20% reduction in the thickness of the concrete pavements should be expected, leading to less use of natural resources and to a further 10% reduction in costs.
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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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Algassem, Omar. "Parameters Affecting the Blast Performance of High Strength Fibre Reinforced Concrete Beams." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35022.
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A limited number of studies have been conducted in the literature in order to investigate the behaviour of high-strength fibre-reinforced concrete (HSFRC) structural components subjected to blast loads. This study summarizes the results of a research program investigating the potential of using steel fibres to improve the blast performance of high-strength reinforced concrete beams. As part of the experimental investigation twenty beams were tested, including nine beams tested under static four-point bending, and eleven beams tested under dynamic blast loads using a shock-tube. Parameters considered in the study include the effect of concrete strength, steel fibres, fibre content, fibre type, longitudinal reinforcement ratio, and presence of shear reinforcement. All beams in the study have identical dimensions, with a cross-section of 125 x 250 mm and length of 2440 mm. To manufacture the specimens, two beams were cast with normal-strength self-consolidate concrete (SCC), with a specified strength of 50 MPa, while the remaining beams were cast with either plain or fibre-reinforced high-strength concrete having a compressive strength which varied between 95-110 MPa. The steel fibre content in the HSFRC beams varied between 0.5 and 1.0%, by volume of concrete. To investigate the effect of reinforcement ratio (ρ), the beams were reinforced with 2-#4 (American size) bars, 2-15M bars or 2-20M bars (ρ = 1.02%, 1.59%, and 2.41%, respectively). The majority of the plain concrete beams had transverse reinforcement which consisted of 6 mm stirrups arranged at a spacing of 100 mm in the shear spans, while most of the HSFRC beams were built without stirrups. The results indicate that all the parameters in this study (reinforcement ratio, presence of stirrups, concrete strength, steel fibres, fibre content and fibre type) affected the static and blast response of the beams, however, the results demonstrate that steel fibres have a more remarkable effect when compared to the other parameters. The provision of fibres is found to improve the blast performance of the HSC beams by increasing shear capacity, reducing maximum and residual mid-span displacements, reducing blast fragments and increasing damage tolerance.
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Burrell, Russell P. "Performance of Steel Fibre Reinforced Concrete Columns under Shock Tube Induced Shock Wave Loading." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23516.
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It is important to ensure that vulnerable structures (federal and provincial offices, military structures, embassies, etc) are blast resistant to safeguard life and critical infrastructure. In the wake of recent malicious attacks and accidental explosions, it is becoming increasingly important to ensure that columns in structures are properly detailed to provide the ductility and continuity necessary to prevent progressive collapse. Research has shown that steel fibre reinforced concrete (SFRC) can enhance many of the properties of concrete, including improved post-cracking tensile capacity, enhanced shear resistance, and increased ductility. The enhanced properties of SFRC make it an ideal candidate for use in the blast resistant design of structures. There is limited research on the behaviour of SFRC under high strain rates, including impact and blast loading, and some of this data is conflicting, with some researchers showing that the additional ductility normally evident in SFRC is absent or reduced at high strain loading. On the other hand, other data indicates that SFRC can improve toughness and energy-absorption capacity under extreme loading conditions. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube.
A total of 13 half-scale steel fibre reinforced concrete columns, 8 with normal strength steel fibre reinforced concrete (SFRC) and 5 with an ultra high performance fibre reinforced concrete (UHPFRC), were constructed and tested under simulated blast pressures. The columns were designed according to CSA A23.3 standards for both seismic and non-seismic regions, using various fibre amounts and types. Each column was exposed to similar shock wave loads in order to provide direct comparisons between seismic and non-seismically detailed columns, amount of steel fibres, type of steel fibres, and type of concrete.
The dynamic response of the columns tested in the experimental program is predicted by generating dynamic load-deformation resistance functions for SFRC and UHPFRC columns and using single degree of freedom dynamic analysis software, RCBlast. The analytical results are compared to experimental data, and shown to accurately predict the maximum mid-span displacements of the fibre reinforced concrete columns under shock wave loading.
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Warnock, Robyn Ellen Civil & Environmental UNSW. "Short-term and time-dependent flexural behaviour of steel fibre-reinforced reactive powder concrete." Awarded by:University of New South Wales. Civil and Environmental, 2006. http://handle.unsw.edu.au/1959.4/23027.
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This thesis presents an experimental and theoretical study of the material and structural behaviour of a Steel-Fibre reinforced Reactive Powder Concrete (SF-RPC). The experimental program consisted of three phases. Phase 1 involved the development of a design mix for use throughout the remainder of the study. Phase 2 consisted of an in-depth investigation into the material properties of the mix. The final phase of the experimental component was the testing of 16 plain and prestressed SF-RPC beams. Twelve beams were tested under short-term loading to determine their cracking and ultimate moment capacity. The remaining 4 beams were used to investigate the time-dependent flexural behaviour of prestressed SF-RPC slabs. The material properties were measured using a range of short-term tests and included the compressive and flexural behaviour, static chord modulus of elasticity and crack mouth opening. In addition to the short-term tests, investigation into the time-dependent material behaviour was undertaken and included the creep and shrinkage characteristics of the material. The response of the material to various curing conditions was also investigated. The structural behaviour investigated included the short-term flexural moment-curvature response and load-deflection behaviour of beams and slabs along with the crack patterns of both plain and prestressed SF-RPC members. In addition to the investigations into the short-term flexural behaviour, a study into the time-dependent flexural behaviour was also undertaken. There are currently 2 available models for predicting the flexural response of plain and prestressed RPC cross-sections. The analytical phase of this investigation involved an evaluation of these models. Based on the experimental findings and analysis, a modified model was proposed for calculating the short-term flexural behaviour of plain and prestressed SF-RPC beams. The applicability of an age-adjusted effective modulus method for calculating the time-dependent deformations of prestressed SF-RPC slabs under various levels of sustained loads was also evaluated and found to be adequate with minor refinements.
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Balafas, Ioannis. "Fibre-reinforced-polymers versus steel in concrete bridges : structural design and economic viability." Thesis, University of Cambridge, 2004. https://www.repository.cam.ac.uk/handle/1810/284032.
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Neumann, Michael J. E. "An experimental investigation into the effectiveness of steel fibre-reinforced concrete relative to conventional mesh-reinforced concrete in thin shell construction." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/8313.
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Includes bibliographical references.This report presents the results of an investigation into the suitability of steel-fibre reinforced concrete (SFRC) as a building material. The performance of the SFRC is gauged relative to conventional steel mesh-reinforced concrete. The report begins with the historical background of fibre-reinforcing, its development and diversity in modern times. The theoretical principles governing the strength of SFRC are formulated, followed by an extensive review of factors influencing the fibre's potential and its subsequent effect on the mechanical properties of a concrete matrix. The experimental program is thereafter detailed in two stages: the "Efficiency and Proving Phase" followed by the "Application Phase". The former involves a series of tests to determine the most promising fibre of the five types available, while the latter compares the strength properties of slabs and arches reinforced with this fibre to those reinforced with wire mesh. The test results obtained from the two phases are evaluated and discussed in the succeeding two sections and the report ends with the conclusions drawn and recommendations regarding the effectiveness of SFRC relative to mesh-reinforced concrete.
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Carlswärd, Jonas. "Shrinkage cracking of steel fibre reinforced self compacting concrete overlays : test methods and theoretical modelling /." Luleå : Division of Structural Engineering, Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1544/2006/55/LTU-DT-0655-SE.pdf.
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Hu, Hang. "Mechanical properties of blended steel fibre reinforced concrete using manufactured and recycled fibres from tyres." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21168/.
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Hosan, Md Anwar. "Residual mechanical properties of steel fibre reinforced geopolymer concrete (SFRGC) after exposure to elevated temperatures." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/1341.
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This study presents the effects of two types of alkali activators (Na and K-based) on the residual mechanical properties of steel fibre reinforced geopolymer concretes (SFRGC) after exposed to various elevated temperatures and compared with those of steel fibre reinforced concrete (SFRC). Results show that the SFRGC containing Na- based activators exhibited much higher residual compressive and indirect tensile strength at all elevated temperatures including at ambient condition than its K-based counterpart and SFRC.
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Incerti, Andrea. "Steel and macro-synthetic self-compacting fibre reinforced concrete, experimental study on the long-term deformations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3265/.
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Experimental study on the long-term deformations of the fibre reinforced concrete.
Steel and macro-synthetic fibers were used to evaluate the shrinkage, creep, mid-span deflection, cracking and rupture analysis of three different types of samples.
At the end the main topics of ACI guidelines were analyzed in order to perform an overview of design.
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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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Tazaly, Zeinab. "Punching Shear Capacity of Fibre Reinforced Concrete Slabs with Conventional Reinforcement : Computational analysis of punching models." Thesis, KTH, Bro- och stålbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118825.
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Steel fibre reinforced concrete is not a novel concept, it has been around since the mid-1900s, but despite its great success in shotcrete-reinforced rock walls and industrial floors it has not made any impact on either beams or elevated slab. Apparently, the absence of standards is the main reason. However, the combination of steel fibre reinforced concrete and conventional reinforcement has in many researches shown to emphasize good bearing capacrty. In this thesis, two punching shear capacity models have been analysed and adapted on 136 test slabs perfomred by previous researchers. The first punching model altemative is proposed in DAfStB - BetonKalender 201l, and the second punching model alternative is established in Swedish Concrete Association - Report No. 4 1994. Due to missing information of the experimental measured residual tensile strength, a theoretical residual tensile strength was estimated in two different manners to be able to adapt the DAfStB punching model altemative on the refereed test slabs. The first solution is an derivation of a suggestion made by Silfiverbrand (2000) and the second solution is drawn from a proposal made by Choi etal. (2007). The result indicates that the SCA punching model alternative is easier to adapt and provides the most representative result. Also DAfStb altemative with the second solution of estimating the residual strength contributes to arbitrary result, however due to the uncertainty of the estimation of the residual tensile strength, the SCA punching model is recommended to be applied until further investigation can confirm the accuracy of the DAfStB alternative with experimentally obtained residual tensile strength.
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Ali, Ahsan [Verfasser], Thomas [Akademischer Betreuer] Bier, Thomas [Gutachter] Bier, and Klaus [Gutachter] Holschemacher. "Bond behavior of lightweight steel fibre-reinforced concrete / Ahsan Ali ; Gutachter: Thomas Bier, Klaus Holschemacher ; Betreuer: Thomas Bier." Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2017. http://d-nb.info/1221069500/34.
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Mohr, Arno Wilhelm. "Moment redistribution behaviour of SFRC members with varying fibre content." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20250.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Steel fibre reinforced concrete (SFRC) is the most prominent fibre reinforced concrete composite that was engineered to enhance the material’s post-cracking behaviour. In certain situations it is utilised to replace conventional reinforcement and considered to be more cost-efficient. The purpose of this research is to characterise the moment redistribution behaviour of a statically indeterminate SFRC structure with varying volumes of fibres, with the focus on the development of the moment redistribution accompanied by the rotation of the plastic hinges at the critical sections in the structure. The material properties were characterised with a series of experimental tests. The compression behaviour was obtained with uniaxial compression tests while the uniaxial tensile behaviour was obtained with an inverse analysis performed according to flexural test results. These properties were utilised to derive a theoretical moment-curvature relation for each SFRC member which supplied the basis for the characterised moment-rotation behaviour and the finite element analyses (FEA) performed on the statically indeterminate structure. Experimental tests were conducted on the statically indeterminate structure in laboratory conditions to validate the theoretical findings. For the different SFRCs the material properties in compression were similar, while it resulted in an increased tensile resistance with an increase in the volume steel fibres. The theoretical momentcurvature and moment-rotation responses also indicated an increased structural capacity and member ductility with an increase in the volume fibres. From the finite element analyses the computational moment redistribution-plastic rotation relations were obtained. It was found that the final amount of moment redistribution decreased with an increase in the fibre volume, but that the rotational capacity increased. It was found that the experimental moment-curvature and moment-rotation results correlate well with the theoretical predictions. Also, unexpected structural behaviour was observed, but the issue was addressed with applicable computational analyses which confirmed the possible causes. It was concluded that the computational moment redistribution approximations were reasonably accurate. A parameter study indicated that the crack band width differed among the different SFRC members.
AFRIKAANSE OPSOMMING: Staal vesel versterkte beton (SVVB) is die mees vooraanstaande vesel versterkte beton mengsel wat ontwikkel is om die materiaalgedrag na kraakvorming te verbeter. In sekere situasies kan dit gebruik word om konvensionele staal te vervang en lei soms to koste vermindering . Die einddoel van die studie is om die moment herverdeling gedrag te karaktiseer vir ‘n statiese onpebaalbare SVVB struktuur deur die invloed van verskillende volumes vesels en die rotasie kapasiteit by die kritieke posisies in ag te neem. Die materiaal eienskappe was geidentifiseer met ‘n reeks eksperimentele toetse. Die druk gedrag was geïdentifiseer deur eenassige druktoetse, terwyl die eenassige trek gedrag bekom is met die implementasie van ‘n inverse analise van die uitgevoerde buig toetse. Hierdie eienskappe is gebruik om die teoretise moment-kromming verhouding vir elke mengsel te bekom. Hierdie verhoudings word as die basis bestempel vir die teoretiese moment-rotasie verhouding en die eindige element analises (EEA) wat op ‘n staties onbepaalbare struktuur toegepas is. Eksperimentele toetse is op hierdie voorgestelde struktuur toegepas om die teoretiese verwagtings te verifieer. Dit is gevind dat die druk gedrag ooreenstem tussen die verskillende mengsels, alhoewel ‘n toename in die trek kapasiteit ervaar is met ‘n toename in die volume vesels. Die teoretiese momentkromming en moment-rotasie verwantskappe stel ook voor dat die strukturele kapasiteit en duktiliteit toeneem met ‘n toename in die volume vesels. Die teoretiese moment herverdeling-plastiese rotasie verwantskapppe is verkry deur middel van die eindige element analises. Dit is gevind dat die aantal moment herverdeling by faling afgeneem het vir ‘n toename in die volume vesels, maar dat dit to ‘n groter rotasie kapasiteit gelei het. Van die eksperimentele resultate is dit afgelei dat die teoretiese moment-kromming en momentrotasie verwantskappe goeie benaderings voorstel. Sekere invloede van die opstelling het daartoe gelei dat onverwagte strukturele gedrag bekom is, maar die moontlike invloede is verifieer met eindige element analises. Dit is afgelei dat die teoretiese beramings van die moment herverdeling gedrag redelik akkuraat is. ‘n Parameter studie het getoon dat die kraak spasiëring verskil tussen mengsels met verskillende volumes vesels.
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Ige, Olubisi A. "Key factors affecting distribution and orientation of fibres in steel fibre reinforced concrete and subsequent effects on mechanical properties." Thesis, University of Portsmouth, 2017. https://researchportal.port.ac.uk/portal/en/theses/key-factors-affecting-distribution-and-orientation-of-fibres-in-steel-fibre-reinforced-concrete-and-subsequent-effects-on-mechanical-properties(186800d2-458c-4c66-9400-5d3e0d1acf58).html.
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Use of fibres to reinforce brittle materials for better performance in buildings and for construction purposes has been employed since time immemorial. Inclusion of steel fibres in concrete therefore, has always improved the post-cracking strength and concrete ductility to a large extent. Nevertheless, there is no doubt that it has become imperative to have more understanding of the internal workings of steel fibre reinforced concrete to fully exploit its potential in practice. In this PhD study, investigation of distribution and orientation of steel fibres within steel fibre reinforced concrete, studying how the positioning of steel fibres in SFRC (steel fibre reinforced concrete) matrix affects the post-cracking strength and other properties that enhance concrete ductility is reported. Variables selected for this study were those considered to influence how steel fibres and concrete matrix associate together during mixing. Hooked-end steel fibres with 50 mm and 60 mm length, of varying diameter resulting in different aspect ratio (ratio of length to diameter of fibre) of 45, 65 and 80, and dosages of 0 kg/m³, 25 kg/m³, 40 kg/m³, 50 kg/m³ and 60 kg/m³ were employed with maximum sizes of coarse aggregate of 10 mm and 20 mm. The same mix proportions of concrete were used throughout the investigation. Workability of the fresh mix was carried out through slump test, flexural performance was assessed through beam and slab tests at 28 day while compressive strength was also measured using cubes. Subsequently, cores were extracted from these panels and X-ray computed tomography was employed for imaging the cores while Insight Toolkit Software was used to analyse the position of fibres in hardened concrete. The experimental results show that the strength performance of steel fibre reinforced concrete improved drastically when compared to plain concrete without fibres. Remarkable improvements were observed at larger dosages of steel fibres, and with fibres with highest aspect ratio of 80 noted to give the best results which suggests that aspect ratio of fibre is critical to SFRC performance. It was found that fibre effects on compressive strength is slightly pronounced, with optimum compressive strength of 68 MPa noticed at fibre dosage of 50 kg/m³ and with fibre of 80 l/d ratio with 20 mm aggregate mixture which is about increase of 8 MPa when compared with plain concrete. Also, in SFRC beams, there were up to 83% increase in maximum stress reached when compared to unreinforced concrete. Moreover, it was found that the results of X-ray CT image analysis by The Insight Toolkit software correlate well with the outcome of mechanical performance of steel fibre reinforced concrete. The slab test results show that mixtures containing 10 mm maximum aggregate size sustain higher load than those of 20 mm counterparts. Harmonization of beam and slab results using yield line analysis revealed that the values of theoretical and experimental failure loads are reasonably close for slabs containing 20 mm maximum aggregate size while the analysis does not agree perfectly with slabs containing 10 mm maximum aggregate size. The 3D rendering images of SFRC cores show that steel fibres are generally positioned horizontally in the slabs which can be seen to be more pronounced in 10 mm maximum aggregate mixes resulting in their ability to sustain higher failure loads. The study has revealed a clear relationship between the geometry of steel fibre and maximum aggregate size, establishing the fibre-aggregate interaction effects on post-cracking capacity of SFRC. Finally, the study has quantitatively measured the distribution and orientation of steel fibre within the concrete matrix while the correlation between the internal mechanism and the mechanical properties of SFRC has been established.
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Labib, Wafa Abdelmajeed. "An experimental study and finite analysis of punching shear failure in steel fibre-reinforced concrete ground-suspended floor slabs." Thesis, Liverpool John Moores University, 2008. http://researchonline.ljmu.ac.uk/5893/.
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The present research is concerned with investigating the structural effect of using steel fibre-reinforcement on the punching shear behaviour of ground-suspended slabs with internal columns. The main objectives of this research were to develop a constitutive model for steel fibre-reinforcement (SFRC), to study experimentally the punching shear behaviour of SFRC with no longitudinal reinforcement and to develop a finite element model that can accurately predict the behaviour of SFRC slabs subjected to punching shear. In this respect, a literature review of the work undertaken by previous researchers on punching shear behaviour of concrete slabs is presented. After that, a constitutive model for SFRC was developed. This is followed by a preliminary finite element analysis (FEA) and experimental study of SFRC slabs. Finally, a finite element model was developed. The literature review revealed that little work has been carried out to study the effect of fibre-reinforcement on the punching shear capacity of concrete slabs. Furthermore, structures, hence a thorough investigation in this area was mandatory. A constitutive model for SFRC in post-cracking stage was developed. This enables one to estimate the tension stiffening behaviour of SFRC based on a simple beam bending test and a statistical model developed in this research, this constitutive model was used later on in the modelling of the SFRC slabs using FEA. In the preliminary FEA, sufficient information for the size and the design of test specimens that were used in the experimental programme was produced. In the experimental study, eight steel fibre-reinforced concrete slab-column connection specimens were tested. The variables of the test specimens include the concrete compressive strength, fibre dosage and fibre aspect-ration.
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Carvalho, Marcelo de Rezende. "Computational Framework for Fracture Simulation of Concrete Structures until Failure." Thesis, University of Sydney, 2019. https://hdl.handle.net/2123/23283.
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The need to predict the fractured behaviour of a structure with a high degree of certainty is becoming a significant problem in the construction industry, whether for designing new structures or for assessing and strengthening existing structures. Considerable advances in the construction industry – with the introduction of new materials and technologies and constant demand for safer, more cost-efficient, sustainable and bold designs – are overturning established design rules. It is becoming critical to bring new predictive tools to assure the safety and serviceability of these structures, and to accomplish the full potential of the new construction designs that are now becoming possible. This research developed a computational framework based on the discrete crack approach that can be efficiently used in engineering for the reliable simulation of the behaviour of concrete structures. The framework is built on an object-oriented finite element platform, specifically tailored to accommodate embedded strong discontinuities, and having tools to improve the simulation of discrete models, such as a non-iterative solution algorithm and a powerful direct sparse solver. Different new formulations are proposed for simulating and capturing crack propagation with embedded discontinuities, which: i) are based on local degrees of freedom, ii) are combined with embedded steel fibres, and iii) require minimum enhanced global degrees of freedom. Multiple case studies are performed for the validation of the new proposed techniques against important laboratory benchmark tests. The framework enables a close-to-reality prediction of the structural behaviour of plain, steel reinforced, and steel fibre reinforced concrete, with improved performance and without convergence issues in fracture simulations.
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Khusru, Shovona. "High performance hybrid structural column with rubberised concrete under axial compressive loading." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/233665/1/Shovona_Khusru_Thesis.pdf.
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Every year millions of tyres are disposed of worldwide in landfill resulting in the rise of an environmental burden. This thesis demonstrates the development of a sustainable novel hybrid double skin tubular column utilizing the scrap tyre rubbers. The proposed column made with rubberised concrete infill, filament wound FRP outer tube and steel inner tube, has been studied extensively through experimental testing, finite element modelling and parametric studies, to understand the structural performance under axial loading. This column, compared to the traditional column will be sustainable and beneficial at the locations demanding improved ductility, energy absorption and corrosion resistance.
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Vargas, Elioth Neyl Zambrana. "Punção em lajes-cogumelo de concreto de alta resistência reforçado com fibras de aço." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-25052018-175031/.
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Neste trabalho investiga-se o comportamento resistente de lajes-cogumelo de concreto armado, analisando-se as possibilidades de melhoria de desempenho com relação ao fenômeno de punção, pelo emprego de concreto de alta resistência, pelo reforço com fibras de aço e pelo uso de armaduras transversais de combate à punção, através de ensaios de modelos de lajes-cogumelo quadradas que representam a ligação laje-pilar para o caso do pilar interno. Apresenta-se também uma revisão de conhecimentos sobre as lajes-cogumelo, o seu comportamento estrutural com ênfase no fenômeno da punção, e os principais conceitos sobre os concretos de alta resistência e os compósitos constituídos de matriz de cimento reforçada com fibras. Doze modelos de laje-cogumelo foram ensaiados com diferentes combinações de concreto de alta resistência, concreto de resistência convencional, armadura transversal e volume de fibras (0%, 0,75% e 1,5%). Um acréscimo significativo de resistência à punção foi observado, devido ao uso de concreto de alta resistência e à adição de fibras. A combinação de concreto de alta resistência com 1,5% de volume de fibras e armadura transversal proporcionaram o dobro de aumento na resistência à punção em relação ao modelo de concreto convencional sem armadura transversal e sem adição de fibras. A adição de fibras é a suposta responsável por cerca de 50% de acréscimo de resistência e o aumento da ductilidade. Outras comparações incluindo as previsões teóricas (Texto Base da NB1/94, CEB/90, AGI 318/89 e EUROCODE N.2) são comentadas.This work investigates the behavior of reinforced concrete flat slabs, analysing the possibility of performance improvement, in relation to punching shear phenomenon, regarding to the use of high strength concrete, the addition of steel fibres and the use of transversal steel reinforcement against punching shear, through tests of flat slab square models that represent the slab-column connection, for the case of an interior column. lt introduce a revision of knowledge of flat slabs, their structural behavior with emphasis on the punching shear phenomenon, and the main concepts about high strength concretes and the composites made of cement matrix reinforced with fibres. Twelve flat slab models were tested in different combinations of high strength concrete, ordinary strength, shear reinforcement and steel fibre volume fraction (0%, 0,75% e 1,5%). A significant increase in the punching shear strength was observed, either due to the use of high strength and the addition of steel fibres. The combination of high strength concrete with 1,5% fibre volume fraction and shear reinforcement provide twice the punching shear resistance of an ordinary concrete strength model without shear reinforcement and without fibre. Fibre addition is supposed to be responsible by about 50% of the resistance improvement and the increase of ductility. Other comparisons including theoretical previsions (Texto Base da NB1/94, CEB/90, ACI 318/89 e EUROCODE N.2) are commented.
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Bam, T. J. "A computer-based justification for using the simple bend test as the basis for predicting the performance of steel hooked-end fibres in reinforced concrete." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/75657.
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The classical test to confirm the performance of a given fibre design for use in reinforced concrete is the pull-out test. While attempts have been made to simulate the performance of such pull-out tests, in practice it has been found that there is a significant disparity between prediction and real-life performance.
The high strength of steel reinforcing fibres is a consequence of the cold wire drawing process and subsequent fabrication. Residual stresses exist in cold drawn wire as a consequence of the elastic response to a non-uniform distribution of plastic strain. This also introduces a yield strength profile where yield strength varies radially through the wire. The question arises as to whether fibre design should use a starting material model that considers these properties.
This thesis examines whether the tensile test, simple bend test and pull-out test provide enough information to define a starting material model that may be used for further design and simulation of such fibres.
Since the details of the wire drawing process and material specification are proprietary and therefore unknown, a sensitivity study was conducted to determine which aspects of the wire drawing process have the greatest effect on the pull-out curve and the following were established as being significant:
• Plastic strain due to wire drawing was shown to be the most important factor.
• The bilinear curve was shown to be a suitable approximation for the stress-strain curve.
• Replacing the plastic strain profile with a single value of average equivalent plastic strain is practical.
The following were established as having negligible effect:
• The consequences of the hooked-end forming process.
• The residual stress profiles due to wire drawing provided that the above was also excluded.
• The hardening law
While inverse analysis demonstrated that all tests provide sufficient information to determine the required properties for this bilinear material model, the pull-out test was shown to provide more accurate approximations of the maximum pull-out force at the first and second peaks and the bend test was shown to produce more accurate approximations of the energy associated with pull-out. Good correlation with the baseline pull-out curve was found for both the isotropic and the kinematic hardening laws and it is concluded that behaviour during pull-out is insensitive to the hardening law.
Sensitivity analysis and characterisation of the material model using an experimental pull-out curve demonstrated the importance of the coefficient of friction. Full characterisation using the pull-out curve therefore requires the solution to a three-variable problem: yield strength, tangent modulus and coefficient of friction. This was a suggested topic for further study.Dissertation (MEng)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
MEng (Mech)
Unrestricted
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Lin, Y. "Optimum design for sustainable 'green' overlays : controlling flexural failure." Thesis, Coventry University, 2014. http://curve.coventry.ac.uk/open/items/b5ba73e5-9cb8-4a0b-ac99-c53b3c3e54ed/1.
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The target of the ‘Green Overlays’ research was a cost effective, minimal disruption, sustainable and environmentally friendly alternative to the wholesale demolition, removal and complete reconstruction of the existing structural concrete pavement. The important problem of flexural resistance for strengthening concrete pavements with structural overlays has been scrutinised. A new mix design method for steel fibre reinforced, roller compacted, polymer modified, bonded concrete overlay has been proposed. The mixes developed were characterized of high flexural strength and high bond strength with the old concrete substrate. ‘Placeability’ and ‘compactability’ of the mix were two dominant issues during laboratory investigation. An innovative approach for establishing the relationship between Stress and Crack Face Opening Displacement for steel fibre reinforced concrete beams under flexure was developed. In addition, a new and simple method for calculating the interfacial Strain Energy Release Rate of both, a two-dimensional specimen and a three-dimensional model of the overlay pavement system were developed. This method can be readily and easily used by practicing engineers. Finally, a new test specimen and its loading configuration for measuring interfacial fracture toughness for concrete overlay pavements were established. The interfacial fracture toughness of a composite concrete beam, consisted of steel fibre-reinforced roller compacted polymer modified concrete bonded on conventional concrete and undergoing flexure, was assessed. In summary, this thesis presents four key findings: A new mix design method for steel fibre-reinforced roller compacted polymer modified concrete bonded on conventional concrete. A new method for establishing the fibre bridging law by an inverse analysis approach. A new, simplified method for calculating strain energy release rate at the interface of a composite beam. A new, innovative technique for calculating strain energy release rate at the interface of an overlaid pavement. The thesis contains a plethora of graphs, data-tables, examples and formulae, suitable for future researchers.
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Kuře, Václav. "Diagnostika průmyslové podlahy z drátkobetonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227582.
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This final thesis is divided into two parts. The first, theoretic part is focused on issue about industrial concrete floors, their production and adjustment. Special attention is paid to the mineral shakes, steel fibres and concrete, which is used to these constructions. There are more information about specific standardized tests of steel fibre concrete and some damages of concrete floors in other chapters. Second part of the diploma thesis is practical. Theoretical knowledge are applied to the actual construction. Survey methodology and diagnostic work are also desribed. Data processing and evaluation with the commentary is also attached to this part. The conclusion summarizes the results and selected findings relating to the issue are also included there.
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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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Gomes, Fernanda. "Influence du revêtement sur le comportement en fatigue des dalles orthotropes : étude d'une solution en BFUP." Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00806298.
Full textAbstract:
Les tabliers métalliques à dalle orthotrope sont sensibles au phénomène de fatigue produit par les charges des poids lourds du trafic. Ce comportement n'est pas précisément prédit avec les méthodes de l'Eurocode 3, compte tenu de la complexité des effets locaux et de la connaissance insuffisante du rôle mécanique du revêtement (diffusion des charges et participation à la flexion locale). De plus l'augmentation du trafic des camions et éventuellement celle des charges admissibles par essieu en Europe tend à rendre ce problème bien plus critique. Le renforcement de ces tabliers est donc souhaitable de façon à prolonger la durée de vie des ponts existants, et aussi augmenter la durabilité des nouveaux ponts. Le béton fibré à ultra hautes performances (BFUP) a été envisagé comme nouvelle solution de revêtement, étant donné ses propriétés mécaniques, ses possibilités de mise en œuvre et sa durabilité. L'objectif de cette thèse, réalisée dans le cadre du projet ANR Orthoplus, est de quantifier expérimentalement l'apport des revêtements couramment utilisés dans les structures à dalle orthotrope et de valider la solution innovante en BFUP. Des essais statiques et dynamiques sur corps d'épreuve à grande échelle (2,40x4,00) m2 ont été réalisés sur la plate-forme d'essai des structures de l'IFSTTAR. Quatre corps d'épreuve ont été testés : tôle de platelage de 14 mm non revêtue et revêtue de 80 mm de béton bitumineux, tôle de 10 mm revêtue de 35 mm de BFUP et tôle de 12 mm revêtue de 35 mm de BFUP. L'influence des différents types de chargement positionnés au centre des corps d'épreuve a été analysée : plaques métalliques type Eurocode 1 et vraies roues de camion. L'étude a porté sur le détail de fatigue: liaison auget-tôle de platelage entre pièces de pont. La contrainte géométrique de fatigue (extrapolation au point chaud) a été évaluée expérimentalement en utilisant deux schémas d'extrapolation linéaire des déformations à proximité du cordon de soudure du détail étudié, le schéma du rapport CECA et celui proposé par l'Institut International de Soudure, à partir des mesures réalisées au-dessous de la tôle de platelage (σT) et sur l'âme de l'auget (σA).La cohérence entre estimation quasi-statique des déformations et comportement sous cycles de fatigue a été vérifiée, ainsi que la rigidification importante apportée par le BFUP, bien que ce dernier ne participe pas avec une connexion totale. Les résultats expérimentaux ont été confrontés à des modèles de différents niveaux de complexité qu'il reste nécessaire de calibrer empiriquement pour prévoir les contraintes géométriques. A partir des contraintes de fatigue obtenues expérimentalement, nous avons calculé la durée de vie des dalles orthotropes testés à l'aide de la règle du cumul linéaire de l'endommagement. Enfin nous avons mené une étude par analyse de cycle de vie d'un pont à dalle orthotrope pour vérifier la pertinence environnementale des différentes solutions de revêtement. Les nombreuses données expérimentales acquises dans ce travail sont de nature à permettre une amélioration significative du dimensionnement rationnel des tabliers à dalle orthotrope et de leur revêtement pour une meilleure prise en compte de leur gestion durable
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Eriksson, Viktor. "Design of Ultra High Performance Fibre Reinforced Concrete Bridges : A Comparative Study to Conventional Concrete Bridges." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-75183.
Full textAbstract:
The use of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) in the construction industry started in the 1990s and has since then been used for bridges all over the world. The mechanical properties and the dense matrix result in lower material usage and superior durability compared to conventional concrete, but the implementation of UHPFRC in the Swedish industry has been delayed. The most evident explanation, based on interview with industry representatives, as to why UHPFRC is not commonly used in Sweden are due to the lack of standards and knowledge. UHPFRC also has a high cement content and the cement industry contributes with high carbon dioxide (CO2) emissions to the total CO2 emissions in the world. This MSc Thesis looks into if a UHPFRC bridge is a feasible alternative to a conventional reinforced concrete structure bridge from design and material usage perspectives, regarding reduction of CO2 emissions. The project’s overall goal is to increase the knowledge in Sweden about the material, regarding the production, mechanical properties and behaviour of UHPFRC, and the design, regarding the difference in design between UHPFRC and conventional concrete bridges. To examine the material, a UHPFRC mixture with short straight steel fibres was developed. Specimens were tested to see how the different fibre contents affect the mechanical properties and which fibre content that is most favourable. Three different fibre contents were tested: 1.5%, 2.0% and 2.5% of the total volume of the mixture. The tested and evaluated mechanical properties were workability, flexural strength, tensile strength, fracture energy, compressive strength and modulus of elasticity. This study does not contain tests of durability of UHPFRC, however trough the literature review it was investigated to what extent the fibres affect the durability. It was concluded that an increase in fibre content results in improved mechanical properties, except for workability and in some cases when using a fibre content of 2.5%. The increase in the mechanical properties is due to the increased cracking resistance and the bond strength between the fibres and the matrix. The decrease in the mechanical properties, e.g. characteristic tensile strength and compressive strength of cylinders, for 2.5% in fibre content can be due to uneven fibre distribution and higher amount of air in the specimens which result in less strength. It was concluded that 2.0% in fibre content is most favourable. It was possible to conclude that the degradation of the fibres takes a long time, however not to what extent the fibres will affect the durability. To evaluate if UHPFRC is a viable economical and environmental alternative to regular concrete bridges, three cases of bridge design are considered. Two cases with UHPFRC (different thickness) and one case with conventional concrete. Up to 2017 only technical guidelines and recommendations for design with UHPFRC existed, but in 2017 the first approved standards in the world were published. The French national standards cover material (NF P18-470, 2016) and design (NF P18-710, 2016) and were used for the design process. The material usage regarding the amount of reinforced UHPFRC/concrete and steel reinforcement as well as the amount of CO2 emissions from the production of cement and steel (fibre and steel reinforcement) used for the bridges in the mid-span and at the support were investigated. The design process was also evaluated. It was concluded that the UHPFRC bridge with an optimized thickness was 47% lighter than the conventional concrete bridge, but the amount of CO2 emissions was still higher (e.g. 23% from the support). To be able to determine if a UHPFRC bridge is a feasible alternative to a conventional concrete bridge, with regards to the reduction of CO2 emissions, the CO2 emissions have to be observed in a wider perspective than only from the production of cement and steel, e.g. fewer transports and longer lifetime.Användningen av ultrahögpresterande fiberbetong (UHPFRC) i anläggningsindustrin började på 1990-talet och har sedan dess använts till broar i hela världen. De mekaniska egenskaperna och den täta UHPFRC matrisen resulterar i lägre materialanvändning och bättre beständighet i jämförelse med konventionell betong, men användningen av UHPFRC har inte slagit igenom i den svenska industrin. De största förklaringarna till varför UHPFRC sällan används i Sverige är för att det inte har funnits kunskap och standarder. UHPFRC har också en hög cementhalt och cementindustrin bidrar med höga koldioxid (CO2) utsläpp till de totala CO2 utsläppen i världen. Den här masteruppsatsen skrevs för att undersöka om en UHPFRC bro är ett möjligt alternativ till en konventionell betongbro ur dimensionering- och materialanvändningssynpunkt med avseende på reduktion av CO2 utsläpp. Projektets övergripande mål är att öka kunskapen om materialet, med avseende på tillverkningen, de mekaniska egenskaperna och beteendet av UHPFRC, och dimensionering, med avseende på skillnaden i dimensionering mellan UHPFRC broar och konventionella betongbroar. I materialdelen utvecklades ett UHPFRC recept med korta raka stålfibrer. Provkroppar testades för att se hur olika fiberinnehåll påverkade de mekaniska egenskaperna och vilket fiberinnehåll som var mest gynnsamt. Tre olika fiberinnehåll testades: 1.5%, 2.0% och 2.5% av total volym av blandningen. De mekaniska egenskaperna som testades och utvärderades var bearbetbarheten, böjhållfasthet, draghållfasthet, fraktur energi, tryckhållfasthet och elasticitetsmodul. Beständigheten av UHPFRC testades aldrig men i vilken omfattning fibrerna påverkar beständigheten undersöktes i den litteraturstudie som skrevs inför testerna och tillverkningen av UHPFRC. Det konstaterades att en ökning i fiberinnehåll resulterade i en ökning av de mekaniska egenskaperna, förutom för bearbetbarheten och i vissa fall när ett fiberinnehåll av 2.5% användes. Ökningen av de mekaniska egenskaperna berodde på det ökande sprickmotståndet och bindningsstyrka mellan fibrerna och matrisen. Minskningen av de mekaniska egenskaperna, till exempel den karakteristiska drag- och tryckhållfastheten, när ett fiberinnehåll på 2.5% i cylindrar användes kan bero på ojämn fiberfördelning och större mängd luft i provkropparna vilket resulterar i lägre hållfasthet. Det konstaterades att ett fiberinnehåll på 2.0% var det mest gynnsamma. Det kunde inte konstateras i vilken omfattning fibrerna påverkar beständigheten men det kunde konstateras att nedbrytningen av fibrerna tar lång tid. I dimensioneringsdelen utformades tre slakarmerade balkbroöverbyggnader, i två fall var överbyggnaden med UHPFRC (olika tjocklekar) och i ett fall var den med konventionell betong. Fram till 2017 fanns det bara tekniska riktlinjer och rekommendationer för UHPFRC men 2017 publicerades de första godkända standarderna i världen. De franska nationella standarderna täcker material (NF P18-470, 2016) och dimensionering (NF P18-710, 2016) och användes vid dimensioneringen. Materialanvändningen med avseende på mängd armerad UHPFRC/betong och slakarmering och mängd CO2 utsläpp från produktionen av cement och stål (fibrer och slakarmering) som användes till broarna i mittenspannet och vid stöden undersöktes. Även dimensioneringsprocessen utvärderades. Det konstaterades att UHPFRC bron med optimerad tjocklek var 47% lättare än betongbron men mängden CO2 utsläpp var fortfarande högre (till exempel 23% högre från stödet). Det konstaterades att om det ska vara möjligt att fastställa att en UHPFRC bro är ett möjligt alternativ till en konventionell betongbro, med avseende på reduktion av CO2 utsläpp, måste CO2 utsläppen ses från ett bredare perspektiv än från bara produktion av cement och stål, till exempel mindre transporter och längre livslängd.
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Miàs, Oller Cristina. "Analysis of time-dependent flexural behaviour of concrete members reinforced with fibre reinforced polymer bar." Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/96914.
Full textAbstract:
In this work, long-term behaviour of FRP RC beams has been investigated both analytically and experimentally to further extend the knowledge in this particular research domain. In this respect, a new methodology to determine the long-term deflections due to creep and shrinkage is presented. Based on multiplicative coefficients, the methodology is straightforward and simple, and therefore suitable to be used in design. In addition, an experimental campaign on two series of GFRP RC beams subject to long-term loading has been performed. Different reinforcement ratios, concrete strengths and sustained load levels have been considered. For comparison purposes steel reinforcement has also been used. The experimental long-term results have been reported and discussed. Furthermore they have been compared to predictions using the most representative procedures, as well as, the proposed methodology presented in this work.En aquest treball, es presenta una nova metodologia per a la determinació de fletxes diferides degudes als efectes de la fluència i la retracció del formigó. La metodologia presentada es basa en coeficients multiplicadors, essent així un mètode directe i simple, apte per ser utilitzar en el disseny. Addicionalment, l’estudi presenta els resultats d’una campanya experimental realitzada en dues etapes, on bigues armades amb barres de material compost han estat sotmeses a càrregues a llarg termini. S’han considerat diferents quanties de reforç, resistències de formigó i nivells de càrrega. Per tal de comparar-ne els resultats, també s’han assajat bigues armades amb barres d’acer. Els resultats experimentals han estat analitzats i comparats amb els models de predicció més significatius, així com amb la metodologia desenvolupada i presentada en aquest estudi.
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Klodner, Jan. "Projekt nosné železobetonové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225479.
Full textAbstract:
This thesis is focusing on general issues of floor concrete slabs, technology, implementation, subsoil models, calculation of internal forces and design approaches. Based on these data the thesis monitors the behaviour of floor slabs according to the various parameters. It also includes three versions of design of the real floor slab, made of steel fibre reinforced concrete, reinforced concrete and prestressed concrete. Economic comparison is also included. In addition it developes a design of the chalice base and reinforced concrete column of the supporting hall system, instead of the original usual base with steel column.
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Voráčová, Tereza. "Stavebně technologický projekt skladovací haly ve Zlíně." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392243.
Full textAbstract:
The final thesis is focused on the solution of the building technology project of storage hall in Zlín. This master’s thesis includes engineering report, studies of major technological stages, solution of transport routes, project of site equipment, design of major machines and mechanisms, technological regulations for steel hall and steel fibre reinforced concrete floor, time schedule, control and test plans for steel hall and steel fibre reinforced concrete floor, budget, time and financial plan, assembly schemes for steel hall and floor assembly.
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Deluce, Jordon Robert. "Cracking Behaviour of Steel Fibre Reinforced Concrete Containing Conventional Steel Reinforcement." Thesis, 2011. http://hdl.handle.net/1807/29523.
Full textAbstract:
It is well known that crack spacings and widths can be reduced with the addition of steel fibres to a concrete mix. However, test data for the tensile behaviour of steel fibre reinforced concrete members containing conventional steel reinforcement (R/FRC members) are scarce relative to those of reinforced concrete (RC) specimens and fibre reinforced concrete (FRC) specimens without reinforcing bars.
In this research program, uniaxial tension tests were conducted on 12 RC and 48 R/FRC specimens in order to observe cracking and tension stiffening behaviour. The parameters under observation were fibre volumetric content, fibre length and aspect ratio, conventional reinforcement ratio and steel reinforcing bar diameter. ‘Dog-bone’ tension tests and bending tests were also performed in order to determine tensile material properties.
It was discovered that currently available crack spacing formulae significantly overestimate the average stabilized crack spacing for R/FRC; therefore, an improved crack spacing model was developed and proposed.
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Elsaigh, Walied Ali Musa Hussein. "Modelling the behaviour of steel fibre reinforced concrete pavements." Thesis, 2007. http://hdl.handle.net/2263/25825.
Full textAbstract:
Steel Fibre Reinforced Concrete (SFRC) is defined as concrete containing randomly oriented discrete steel fibres. The main incentive of adding steel fibres to concrete is to control crack propagation and crack widening after the concrete matrix has cracked. Control of cracking automatically improves the mechanical properties of the composite material (SFRC). The most significant property of SFRC is its post-cracking strength that can impart the ability to absorb large amounts of energy before collapse. Ground slabs are structural applications that could benefit from these advantageous features of the SFRC. Many tests on SFRC ground slabs show that the material can offer distinct advantages compared to plain concrete. In concrete road pavements, SFRC is particularly suitable for increasing load-carrying capacity and fatigue resistance. Not surprisingly, recent years have witnessed acceleration in full-scale tests of SFRC and eventually acceptance of its use in concrete pavements. The use of SFRC in pavements has been slowed down by the absence of a reliable theoretical model to analyse and design these pavements. The analysis of ground slabs has traditionally been based on an elastic analysis assuming un-cracked concrete. Using such a method for SFRC would ignore the post-cracking contribution the SFRC can make to the flexural behaviour of the slab. Despite the growing trend of using methods of analysis based on yield-line theory, which can consider the post-cracking strength of SFRC, these methods were also found to underestimate the load-carrying capacity of SFRC ground slabs. To effectively account for the post-cracking strength of SFRC in the analysis of such slabs requires a method such as the finite element method. In the present work, non-linear methods are used to model the behaviour of SFRC ground slabs subjected to mechanical load. An analytical method is used to determine a tensile stress-strain response for SFRC. In this method, the post-cracking strength of SFRC is taken into account and hence the material model is sensitive to the element size used. The calculated stress-strain response is utilised in finite element analysis of SFRC beams and ground slabs. A smeared crack approach is used to simulate the behaviour of concrete cracking. The analytical method used to determine the tensile stress-strain response, as well as the finite element model, are evaluated using results from experiments on SFRC beams and ground slabs. The analytical results are found to compare well with the observations. The non-linear methods are further used to study the effect of the material model parameters as well as the support stiffness on load-displacement behaviour of SFRC ground slabs. The developed finite element model is shown to be more efficient compared to methods based on the yield-line theory. This is because it produces the load-displacement behaviour of the SFRC ground slab up to a reasonable limit and it provides the tensile stresses as well as the extent of cracking of the slab at every point on the load-displacement response. Using the developed finite element model will allow for considerable material saving since smaller slab thickness can be calculated compared to analytical models currently in use.Thesis (PhD(Transportation Engineering))--University of Pretoria, 2008.
Civil Engineering
PhD
unrestricted
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Katzensteiner, Bryan Oswald. "Use of steel fibre-reinforced concrete in seismic design." Thesis, 1994. http://hdl.handle.net/2429/5364.
Full textAbstract:
In ductile concrete frames designed to withstand reversing seismic loads, the joint regions
typically contain closely-spaced transverse confining hoops in both the beams and columns.
Since placing these hoops is a labour-intensive task, numerous researchers have proposed
removing some of the hoops from the joint regions, and using steel fibre-reinforced concrete
(SFRC) to achieve the same confinement and ductility. To assess the effectiveness of this type
of construction, dynamic tests of two sets of parallel one-bay, two-storey concrete plane frames
were carried out at the University of British Columbia’s Earthquake Engineering Laboratory.
Both sets of frames were identical in geometry and were detailed to the CAN3-A23 .3-M84
Canadian concrete code. The second set was modified by removing approximately every second
beam and column hoop from the joint regions, and adding 30 mm-long x 0.50 mm-diameter
collated hooked-end Dramix (Bekaert) steel fibres to the concrete mix at a loading of 60 k3g/rn
(0.76% by volume). Each set of frames was interconnected with steel-angle cross-braces, and
loaded with the tributary dead load plus 25% snow load.
The dynamic testing programme of the test structures was broken into three phases. The first
phase consisted of determining each structure’s initial natural frequency and viscous damping
ratio by applying low-level excitations and analysing the subsequent structural response. In the
second phase, the main dynamic tests were performed in which each structure was subjected to
eight earthquake acceleration records of increasing magnitude. The third and final phase
consisted of remeasuring the natural frequency of each structure to determine how severely the
frames had been damaged during the main dynamic tests. Results from the low-level excitation tests showed the conventionally-detailed frames to
possess an initial natural frequency of 3.91 Hz and a viscous damping ratio of 2.3%, while the
SFRC frames had an initial natural frequency of 3.13 Hz and a viscous damping ratio of 2.9%.
By the end of the main dynamic tests, the natural frequencies had dropped to 1.76 Hz for the
conventional frames and 1.56 Hz for the SFRC frames, indicating that extensive damage had
been sustained by both sets of frames.
Based on the hysteretic behaviour of the two test structures, the SFRC frames appear to have
performed at least as well as the conventionally-detailed frames. The more rounded shape of the
SFRC hysteresis loops at maximum lateral displacement suggests that inelastic deformations of
the fibres help to dissipate energy during both loading and unloading of the structure. This
additional energy dissipation makes the SFRC well suited for applications in seismic-resistant
construction. Furthermore, the ability of the SFRC members to retain their concrete cover
would possibly allow the members to be repaired by such techniques as epoxy injection
following an earthquake.