Дисертації: "Tensile Reinforcement"

1

Demerdash, Magdy Adel. "An experimental study of piled embankments incorporating geosynthetic basal reinforcement." Thesis, University of Newcastle Upon Tyne, 1996. http://hdl.handle.net/10443/309.

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Basal reinforcement along with individually capped foundation piles is used in cases where both embankment stability and surface settlement control are required. The technique has been utilised to prevent differential settlement between new embankment construction over soft soil and an existing embankment where settlement has ceased. The piled embankment solution is also adopted to prevent differential settlement between an approach embankment constructed over soft soil and the piled foundations of a bridge abutment. The study was conducted to investigate the behaviour of an idealised piled embankment incorporating basal geosynthetic reinforcement. Three-dimensional model tests at self-weight conditions were carried out to evaluate the effect of some of the factors affecting the arching mechanism and the development of surface settlement in piled embankments. The physical model was designed to represent a square grid of individually capped piles centrally located within an embankment. Three different pile cap sizes and four different geosynthetic materials were employed in the experimental study. A movable base supported on hydraulically operated jacks was used to model the soft ground. The use of a movable base permitted the simulation of a worst case scenario in which the soft ground was not involved in the load sharing mechanism. The experimental results indicated the existence of two modes of behaviour pertaining to a shallow and deep mechanism. The piled embankment geometry represented by a combination of height of fill, pile cap size and spacing was found to govern the mode of behaviour. The arching mechanism in the fill was found to be mobilised at a relatively small reinforcement deflection which supported the adoption of the two step approach utilised in designing the basal reinforcement. The circular and parabolic arc geometries were found to be adequate in describing the deflected shape of the reinforcement. The use a modified flexible cable formulation to describe the loaddeflection response of the reinforcement was found to be in good agreement with the experimental results. In addition, the validity of a number of current methods and recommendations relating to the design of piled embankments was addressed. A numerical study was undertaken using FLAC, a plane strain finite difference based programme. The calculated and measured results were compared to assess the suitability of modelling piled embankment behaviour using the finite difference programme. A parametric study was conducted to investigate the role of the basal reinforcement in the load transfer mechanism and in the prevention of surface settlement. The embankment geometry was identified as the significant factor influencing the reduction in differential settlement. A surface settlement mechanism was established based on results of the parametric study.

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2

Nokhasteh, Mohammad-Ali. "Corrosion damaged reinforced concrete beams with debonded tensile span reinforcement." Thesis, University College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294542.

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3

Ostrofsky, David. "Effects of corrosion on steel reinforcement." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002258.

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4

Bertolla, Luca. "Mechanical Reinforcement of Bioglass®-Based Scaffolds." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234586.

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Bioactive glasses exhibit unique characteristics as a material for bone tissue engineering. Unfortunately, their extensive application for the repair of load-bearing bone defects is still limited by low mechanical strength and fracture toughness. The main aim of this work was two-fold: the reinforcement of brittle Bioglass®-based porous scaffolds and the production of bulk Bioglass® samples exhibiting enhanced mechanical properties. For the first task, scaffolds were coated by composite coating constituted by polyvinyl alcohol (PVA) and microfibrillated cellulose (MFC). The addition of PVA/MFC coating led to a 10 fold increase of compressive strength and a 20 fold increase of tensile strength in comparison with non-coated scaffolds. SEM observations of broken struts surfaces proved the reinforcing and toughening mechanism of the composite coating which was ascribed to crack bridging and fracture of cellulose fibrils. The mechanical properties of the coating material were investigated by tensile testing of PVA/MFC stand–alone specimens. The stirring time of the PVA/MFC solution came out as a crucial parameter in order to achieve a more homogeneous dispersion of the fibres and consequently enhanced strength and stiffness. Numerical simulation of a PVA coated Bioglass® strut revealed the infiltration depth of the coating until the crack tip as the most effective criterion for the struts strengthening. Contact angle and linear viscosity measurements of PVA/MFC solutions showed that MFC causes a reduction in contact angle and a drastic increase in viscosity, indicating that a balance between these opposing effects must be achieved. Concerning the production of bulk samples, conventional furnace and spark plasma sintering technique was used. Spark plasma sintering performed without the assistance of mechanical pressure and at heating rates ranging from 100 to 300°C /min led to a material having density close to theoretical one and fracture toughness nearly 4 times higher in comparison with conventional sintering. Fractographic analysis revealed the crack deflection as the main toughening mechanisms acting in the bulk Bioglass®. Time–dependent crack healing process was also observed. The further investigation on the non-equilibrium phases crystallized is required. All obtained results are discussed in detail and general recommendations for scaffolds with enhanced mechanical resistance are served.

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5

Peled, Alva, Zvi Cohen, Steffen Janetzko, and Thomas Gries. "Hybrid Fabrics as Cement Matrix Reinforcement." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77694.

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Hybrid systems with two or more fiber materials were used to combine the benefits of each fiber into a single composite product. Strength and toughness optimization of hybrid thin sheet composites has been studied extensively using combination of different fiber types with low and high modulus of elasticity. Hybrid reinforcement is more significant when the reinforcing structure is in fabric geometry. Fabric structure provides full control on the exact location of each yarn and its orientation in the composite during production, thus maximizes the reinforcing efficiency. A high-strength, high-modulus fiber primarily tends to increase the composite strength with nominal improvements in toughness. A low-modulus fiber expected to mainly improve toughness and ductility. Combination of two or more types of fiber can produce a composite that is both strong and tough as compared to a mono fiber composite. The purpose of the current work was to study hybrid warp knitted fabrics as reinforcement for cementbased composite, having AR (Alkali Resistance) glass and Polypropylene (PP) as the reinforcing yarns. The examined ratios between the two different yarns were 0:100, 25:75, 50:50, 75:25, 100:0 (glass: PP, by percentage). It was found that in the hybrid system, the fracture mechanism is a superposition of the mono systems, and the tensile behavior is a combination between the two materials.

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6

DeYoung, Kenneth Lee. "Flexure shear response in fatigue of fiber reinforced concrete beams with FRP tensile reinforcement." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4894.

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Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 24, 2008) Includes bibliographical references.

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7

Brown, Adrian D. "The use of carbon fibre reinforced cement as tensile reinforcement for concrete structural elements." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287533.

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8

Suncar, Oscar Ernesto. "Pullout and Tensile Behavior of Crimped Steel Reinforcement for Mechanically Stabilized Earth (MSE) Walls." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/566.

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Many research studies made on hundreds of MSE walls have shown that in order to get lower values of lateral earth pressure coefficients from an active condition on the backfill soil, thus lower exerted loads and stresses on the reinforcement, the wall needs to yield. This is typical of extensible polymer-based wall systems, such as geosynthetics. Steel systems, on the other hand, are very rigid and do not allow enough deformation on the wall to generate the active condition. For this research, steel reinforcement for MSE walls that behaves similar to geosynthetics was developed. This was done by using crimps on steel bars that would allow the wall to deform as the crimps straighten. A pullout box was designed and constructed, where tensile and pullout tests were performed on the crimped reinforcement. Different crimp geometries on different bar diameters were tested under a range of confining pressures. From this, force-displacement curves were developed for these crimp geometries that could be used to predict deflections on walls with crimped reinforcement. In addition, the pullout resistance of the crimps in the straighten process was evaluated. This way, the crimps would not only be used to allow the wall to yield, but also as a pullout resistance mechanism. The pullout resistances per crimp for different tensions on the crimp and under a range of overburden pressures were evaluated. By combining the pullout resistance of the crimps and the force-displacement curves, a new internal stability design method was introduced where crimped reinforcement is used to resist both pullout and rupture failure. Also presented here are the pullout resistances of round bars with improved deformations of different diameters. These were found to have the same pullout resistance of square deformed bars with the same cross-sectional area. Round bars are preferred over square bars because they are more corrosion resistant and have longer design life.

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9

Węcławski, Bartosz Tomasz. "The potential of bast natural fibres as reinforcement for polymeric composite materials in building applications." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11670.

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Natural fibre composites (NFCs), which are polymers reinforced with cellulosic bast fibres, have the potential to be applied into a range of building products. They are seen as an alternative to glass fibre reinforced plastics (GFRP) in some applications, because of natural fibres (NF) relatively high strength and low density. Moreover, natural fibres have a set of beneficial traits, such as thermal insulation, thermal stability, biodegradability, and are inherently renewable. Those characteristics are of importance when NF are used as reinforcements in polymer composites, but developments in mechanical performance, reliability and economic viability are still required in order to be adopted fully by industry. The goal of this thesis was the development of a processing methodology for NFC laminate and subsequent material characterisation to assess the developed material suitability for building applications. Research objectives included materials selection, processing route development for laminates and tubes, manufacture of NFC laminates and analysis of mechanical properties in order to find an optimal composition. Hemp and flax fibres were selected as the reinforcement, because both have high mechanical properties and are important bast fibre crops in the European region with established cultivation and processing methods. As a matrix, fossil-fuel based and partially bio-derived thermoset resin systems were used. Handling and processing methodologies were developed for laminates and composite tubes based on filament winding and compression moulding techniques. The effects of the selected factors, namely material composition, volume fraction, processing parameters, reinforcement linear density, yarn twist, lamination sequence, yarn waviness and hybrid hemp-wool reinforcement were subsequently described in mechanical properties analysis of laminates. The influence of weathering conditions on the mechanical performance of the NFCs was examined. Furthermore, a study of NFC tubes under compression was performed. Results showed that the developed laminates reinforced with NF yarns have sufficient mechanical properties to be utilised in sandwich panels and/or tubes. However, a low resistance to moisture-related weathering restricts the developed NFCs for indoor applications.

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10

Gong, Ting. "Tensile behavior of high-performance cement-based composites with hybrid reinforcement subjected to quasi-static and impact loading." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A73914.

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Hochduktile Betone (Engl.: Strain-Hardening Cement-based Composites – SHCC) und Textilbetone (engl.: Textile Reinforced Concrete – TRC) sind zwei neuartige Faserbetone, die ein duktiles und dehnungsverfestigendes Zugverhalten aufweisen. SHCC bestehen aus feinkörnigen Zementmatrizen und kurzen Hochleistungspolymerfasern, während TRC eine Kombination aus feinkörnigen Zementmatrizen und kontinuierlichen zwei- oder dreidimensionalen Textilschichten darstellt. Letztere bestehen aus Multifilamentgarnen aus Kohlenstoff, alkalibeständigem Glas oder Polymerfasern. Die hohe elastische Verformbarkeit beider Verbundwerkstoffe bis zum Erreichen der Zugfestigkeit entsteht aus der sukzessiven Bildung multipler feiner Risse. Neben der hervorragenden Risskontrolle und Duktilität weisen diese Verbundwerkstoffe ein hohes Energieabsorptionsvermögen auf, was in Bezug auf kurzzeitdynamische Belastungen eine durchaus erstrebenswerte Eigenschaft darstellt. Obwohl SHCC eine höhere Dehnungskapazität als herkömmliche TRC zeigen, weisen die Textilbetone eine erheblich höhere Zugfestigkeit auf. Darüber hinaus besitzen die textilbewehrten Betone deutlich niedrigere Einflüsse von Anwendungstechnologie und Maßstab auf das Zugverhalten, d. h. eine bessere Robustheit. Daher stellt die Kombination dieser beiden Bewehrungskonzepte einen vielversprechenden Ansatz dar. Während die Kurzfasern für eine bessere Risskontrolle und Erstrissfestigkeit sorgen, sichern die Textilgelege eine hohe Zugfestigkeit sowie Steifigkeit im gerissenen Zustand und eine gleichmäßige Verteilung der Kräfte in der Verstärkungsschicht bzw. im Bauteil. Dieser synergetische Effekt kann jedoch nur durch eine zielgerichtete Materialentwicklung erreicht werden, die eine grundlegende Materialcharakterisierung unter verschiedenen Belastungsszenarien erfordert. Im Rahmen des DFG-finanzierten Graduiertenkollegs GRK 2250 „Impaktsicherheit von Baukonstruktionen durch mineralisch gebundene Komposite“ werden duktile und Impakt resistente Komposite entwickelt, charakterisiert und erprobt, die als dünne Verstärkungsschichten auf bestehende Konstruktionen bzw. Bauelemente aufgetragen werden und dadurch deren Widerstandsfähigkeit und Resilienz gegen extreme kurzzeitdynamische Beanspruchungen signifikant erhöhen. Die in der vorliegenden Arbeit vorgestellten Ergebnisse wurden im Rahmen des A3-Projektes innerhalb des GRK 2250/1 erzielt. Ziel dieser Arbeit war es, die grundlegenden mechanischen Eigenschaften und die Dehnratenabhängigkeit von mineralisch gebundenen Kompositen mit hybrider Faserbewehrung zu erfassen und zu beschreiben. Das Forschungskonzept besteht aus systematischen und parametrischen Untersuchungen der einzelnen Komponenten (Faser, Textil, zementgebundene Matrix), ihres Verbundes und der entsprechenden Verbundwerkstoffe. Hierfür wurden zweckbestimmte Prüfkonfigurationen und dreidimensionale Messverfahren angewandt, die in anderen Projekten des GRK 2250/1 entwickelt wurden. Außer uniaxialen, quasistatischen und dynamischen Zugversuchen wurden quasistatische und dynamische Einzelgarnauszugsversuche durchgeführt. Die wichtigsten untersuchten Materialparameter waren die Art der Kurzfaserbewehrung und der Textilien (Material, geometrische und Oberflächeneigenschaften, Art der Tränkung usw.). Auf Basis der mechanischen Experimente wurde ein analytisches Modell eingesetzt und angepasst, dass das Zugverhalten solcher Komposite in Abhängigkeit von verschiedenen Materialparametern abbilden soll. Zusätzlich zu der detaillierten Beschreibung der Materialeigenschaften, der maßgebenden Mechanismen und synergetischen Effekte bilden die erzielten Ergebnisse eine umfangreiche experimentelle Basis für eine empirische und Modell gestützte Weiterentwicklung und Optimierung dieser Verbundwerkstoffe mit Hinblick auf wirtschaftliche und ökonomische Aspekte.
Strain-hardening cement-based composites (SHCC) and textile-reinforced concrete (TRC) are two novel types of fiber-reinforced cementitious composites that exhibit ductile, strain-hardening tensile behavior. SHCC comprises fine-grained cementitious matrices and short, high-performance polymer fiber, while TRC is a combination of a fine-grained, cementitious matrix and continuous two- or three- dimensional textile layers of multi-filament yarns, usually made of carbon or alkali-resistant glass. Both composites yield high inelastic deformations in a strain-hardening phase due to the successive formation of multiple fine cracks. Such cracking behavior stands for high energy absorption of the composites when exposed to extreme loading, without abrupt loss of load-bearing capacity. In comparative terms, SHCC shows superior strain capacity, while TRC yields considerably higher tensile strength. The addition of short fibers strengthens the matrix by efficiently restraining the micro-cracks’ growth and reducing spallation, while the textile reinforcement ensures a secure confinement of the reinforced concrete element (substrate to be strengthened), as well as a favorable stress distribution. The combination of SHCC and textile reinforcement is expected to deliver high tensile strength and stiffness in the strain-hardening stage along with pronounced multiple cracking. In order to achieve a favorable synergetic effect, a purposeful material design is required based on a clear understanding of the mechanical interactions in the composites. In the framework of the DFG Research Training Group GRK 2250, which aims at enhancing structural impact safety through thin strengthening layers made of high-performance mineral-based composites, this work focuses on developing hybrid fiber-reinforced cementitious materials to be applied on the impact rear side. The development concept builds upon a systematic investigation of various aspects of the mechanical behaviors of SHCC and textile at quasi-static and impact strain rates, including the bond properties of fiber to matrix and textile to matrix. Accordingly, uniaxial quasi-static tension tests were first performed on SHCC, bare textile, and hybrid-reinforced composite specimens. The parameters under investigation were types of short fiber and textile reinforcements, reinforcing the ratio for textile as well as bond properties between textile and the surrounding SHCC. Furthermore, impact tension tests were performed to study the strain rate effect on the synergetic composite response. Finally, single-yarn pull-out tests were carried out under both quasi-static and impact loading rates to supplement the comparative assessment of the hybrid fiber-reinforced composites. These tests yielded shear strength-related parameters for quantifying the bond properties of different materials, which were then used as input of the analytical model developed to describe the mechanics of crack propagation and tension stiffening effect of textile-reinforced composites without short fibers. This model is the first step towards a comprehensive analytical description of the tensile behavior of hybrid fiber-reinforced composites based on the experimental data and input parameters attained through the work at hand.

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11

Godbole, Chinmay. "The Influence of Reinforcement on Microstructure, Hardness, Tensile Deformation, Cyclic Fatigue and Final Fracture behavior of two Magnesium Alloys." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1321633235.

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12

DeFreese, James Michael. "Glass Fiber Reinforced Polymer Bars as the Top Mat Reinforcement for Bridge Decks." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/36289.

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The primary objective of this research was to experimentally investigate material and bond properties of three different types of fiber reinforced polymer (FRP) bars, and determine their effect on the design of a bridge deck using FRP bars as the top mat of reinforcement. The properties evaluated include the tensile strength, modulus of elasticity, bond behavior, and maximum bond stress. The experimental program included 47 tensile tests and 42 beam end bond tests performed with FRP bars. Tensile strength of the bars from the tensile testing ranged from 529 MPa to 859 MPa. The average modulus, taken from all the testing, for each type of bar was found to range from 40 GPa to 43.7 GPa. The maximum bond stress from the beam end bond tests ranged from 9.17 MPa to 25 MPa. From the tests, design values were found in areas where the properties investigated were related. These design values include design tensile strength, design modulus of elasticity, bond coefficient for deflection calculations, bond coefficient for crack width calculations, and development length. The results and conclusions address design concerns of the different types of FRP bars as applied in the top mat of reinforcement of a bridge deck. A secondary objective was to evaluate the disparity in results between direct pullout tests, and beam end bond tests. Results from the experimentally performed beam end bond test were compared to previous literature involving the direct pullout tests. Results from the performed beam end bond tests were higher than all of the literature using direct pullout results. No recommendations were given on the disparity between the two test methods.
Master of Science

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13

Barnes, Glen James. "An experimental investigation on the properties and performance of geogrid and geocomposite as subgrade reinforcement in granular pavements." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/129219/2/Glen%20Barnes%20Thesis.pdf.

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This experimental study focuses on developing a new laboratory testing model that expedites the performance verification process for future geosynthetic products, for use in foundation stabilisation. Through a series of tensile and pullout tests on geosynthetic and CBR tests on geosynthetic reinforced subgrade using a bespoke CBR mould, this research highlights the benefits of including geosynthetics in granular pavement design. Further research will allow future road pavement designs in Australia to include geosynthetics as part of design specifications and reduce the environmental impact of pavement construction by minimising the required subbase layer thickness without compromising on foundation strength.

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14

Vergani, C. "SPATIAL AND TEMPORAL DYNAMICS OF ROOT REINFORCEMENT IN ALPINE FORESTS." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/232578.

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Protection forests represent an effective tool to prevent and mitigate hydrogeological instabilities and are object of renewed interest in the European Alps, where there is a long history of cohabitation between people and natural hazards. The quantification of the effects of forests against the different types of natural hazards is however still a challenge, and represents a key step for the implementation of an integrated protection strategy able to combine engineering structures with forests. Forests provide different protection mechanisms depending on the type of natural hazards we consider. The aim of this work is to give a contribution to the quantification of the effects of forest vegetation against shallow landslides. Mechanical reinforcement of soil given by root systems is considered the most important contribution of alpine forests against shallow landslides. Many studies proved that it plays a key role in slope stability, but its quantification is still a challenge due to the huge variability that characterizes root reinforcement values. Understanding and modeling this variability is a key step in the development of stability models able to account for the role of vegetation, and to provide practical guidelines to foresters involved in the management of protection forests. Root mechanical reinforcement depends primarily on the density and distribution of roots of different diameter class (i.e. number and size of roots) and on their mechanical properties. Both these factors are subject to a huge variability in natural slopes. We can distinguish a spatial variability, due to the different environmental and stand characteristics that influence root systems development, and a temporal variability, due to the anthropic or natural disturbances that modify the forest stand and as consequence the root systems. The first section of this work presents a review on the role of forests against shallow landslides and the state of the art of the studies on root reinforcement, the models used for its quantification and its implementation in the stability models. The second section deals with the spatial variability of root reinforcement at both the regional and stand scale. The variability of root mechanical properties in several alpine species is analyzed basing on a wide data base obtained by laboratory tensile tests on roots coming from different forest sites in northern Italy, and a possible criterion for the interpretation and synthesis of this variability is proposed. The influence of both root mechanical properties and root distribution variability on the estimation of root reinforcement is then assessed in the case of a common alpine species, Picea abies, by means of the Root Bundle Model. Results show the importance of micro variability of root distribution at the stand scale that heavily affects root reinforcement estimation; the variability of root mechanical properties on the other hand cannot be ignored because it can lead to important errors in root reinforcement estimation. In the third section of the work the temporal dynamics of root reinforcement as consequence of logging activities are studied with intensive field work carried out in two different case of study, two mixed Silver fir – Norway spruce stands in the Italian Alps and four Norway spruce stands in the Swiss Alps. New experimental data for the quantification of root reinforcement decay after cutting for the selected species are provided, paying attention to both root mechanical properties and root distribution. A model for the estimation of root reinforcement decay that takes into account both the processes is proposed. Results show the importance of modeling horizontal root distribution in the study on root reinforcement decay and underline the need of further research on the role of natural regeneration in stabilizing gaps after cutting.

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15

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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16

Scheidt, Matthew. "Lightweight Aluminum Structures with EmbeddedReinforcement Fibers via Ultrasonic Additive Manufacturing." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469112453.

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17

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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18

Luna, Andrew I. "Lateral Resistance of H-Piles and Square Piles Behind an MSE Wall with Ribbed Strip and Welded Wire Reinforcements." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6346.

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Bridges often use pile foundations behind MSE walls to help resist lateral loading from seismic and thermal expansion and contraction loads. Overdesign of pile spacing and sizes occur owing to a lack of design code guidance for piles behind an MSE wall. However, space constraints necessitate the installation of piles near the wall. Full scale lateral load tests were conducted on piles behind an MSE wall. This study involves the testing of four HP12X74 H-piles and four HSS12X12X5/16 square piles. The H-piles were tested with ribbed strip soil reinforcement at a wall height of 15 feet, and the square piles were tested with welded wire reinforcement at a wall height of 20 feet. The H-piles were spaced from the back face of the MSE wall at pile diameters 4.5, 3.2, 2.5, and 2.2. The square piles were spaced at pile diameters 5.7, 4.2, 3.1, and 2.1. Testing was based on a displacement control method where load increments were applied every 0.25 inches up to three inches of pile deflection. It was concluded that piles placed closer than 3.9 pile diameters have a reduction in their lateral resistance. P-multipliers were back-calculated in LPILE from the load-deflection curves obtained from the tests. The p-multipliers were found to be 1.0, 0.85, 0.60, and 0.73 for the H-piles spaced at 4.5, 3.2, 2.5, and 2.2 pile diameters, respectively. The p-multipliers for the square piles were found to be 1.0, 0.77, 0.63, and 0.57 for piles spaced at 5.7, 4.2, 3.1, and 2.1 pile diameters, respectively. An equation was developed to estimate p-multipliers versus pile distance behind the wall. These p-multipliers account for reduced soil resistance, and decrease linearly with distance for piles placed closer than 3.9 pile diameters. Measurements were also taken of the force induced in the soil reinforcement. A statistical analysis was performed to develop an equation that could predict the maximum induced reinforcement load. The main parameters that went into this equation were the lateral pile load, transverse distance from the reinforcement to the pile center normalized by the pile diameter, spacing from the pile center to the wall normalized by the pile diameter, vertical stress, and reinforcement length to height ratio where the height included the equivalent height of the surcharge. The multiple regression equations account for 76% of the variation in observed tensile force for the ribbed strip reinforcement, and 77% of the variation for the welded wire reinforcement. The tensile force was found to increase in the reinforcement as the pile spacing decreased, transverse spacing from the pile decreased, and as the lateral load increased.

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Karlsson, Hanna. "Strength Properties of Paper produced from Softwood Kraft Pulp : Pulp Mixture, Reinforcement and Sheet Stratification." Doctoral thesis, Karlstads universitet, Avdelningen för kemiteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-5612.

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For paper producers, an understanding of the development of strength properties in the paper is of uttermost importance. Strong papers are important operators both in the traditional paper industry as well as in new fields of application, such as fibre-based packaging, furniture and light-weight building material. In the work reported in this thesis, three approaches to increasing paper strength were addressed: mixing different pulps, multilayering and reinforcement with man-made fibres. In specific: The effects of mixing Swedish softwood kraft pulp with southern pine or with abaca (Musa Textilis) were investigated. Handsheets of a softwood kraft pulp with the addition of abaca fibres were made in a conventional sheet former. It was seen that the addition of abaca fibres increased the tearing resistance, fracture toughness, folding endurance and air permeance. Tensile strength, tensile stiffness and tensile energy absorption, however, decreased somewhat. Still it was possible to add up to about 60% abaca without any great loss in tensile strength. As an example, with the addition of 30% abaca, the tear index was increased by 36%, while the tensile index was decreased by 8%. To study the effect of stratification, a handsheet former for the production of stratified sheets, the LB Multilayer Handsheet Former was evaluated. The advantage of this sheet former is that it forms a stratified sheet at low consistency giving a good ply bond. It was shown to produce sheets with good formation and the uniformity, evaluated as the variation of paper properties, is retained at a fairly constant level when the number of layers in the stratified sheets is increased. The uniformity of the sheets produced in the LB Multilayer Handsheet Former is generally at the same level as of those produced in conventional sheet formers. The effects of placing southern pine and abaca in separate layers, rather than mixing them homogeneously with softwood pulp were studied. Homogeneous and stratified sheets composed of softwood and southern pine or softwood and abaca were produced in the LB Multilayer Handsheet Former. It was found that by stratifying a sheet, so that a pulp with a high tear index and a pulp with a high tensile index are placed in separate layers, it was possible to increase the tear index by approximately 25%, while the tensile index was decreased by 10-20%. Further, by mixing a pulp with less conformable fibres and no fines with a pulp with more flexible fibres and fines, a synergy in tensile strength (greater strength than that predicted by linear mass fraction additivity) was obtained. The effects of stratifying sheets composed of softwood and abaca were compared to the effects of refining the softwood pulp. Homogeneous and stratified sheets composed of softwood with three different dewatering resistances and abaca were also produced in the LB Multilayer Handsheet Former. It was found that by stratifying the sheets the tear index was retained while the tensile index was increased by the refining. The effects of reinforcing softwood pulp of different dewatering resistances with man-made fibres with low bonding ability were also investigated. Man-made fibres (i.e. regenerated cellulose, polyester and glass fibres) were added in the amounts 1, 3, or 5 wt% to softwood pulp of three different dewatering resistances. It was found that with refining of a softwood pulp and subsequent addition of long fibres with low bonding ability the tensile-tear relationship can be shifted towards higher strength values. The bonding ability of the man-made fibres was evaluated by pull-out tests and the results indicated that, in relation to the fibre strength, regenerated cellulose (lyocell) was most firmly attached to the softwood network while the glass fibres were most loosely attached.

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Gong, Ting [Verfasser], Viktor [Gutachter] Mechtcherine, Viktor [Akademischer Betreuer] Mechtcherine, Christina [Gutachter] Scheffler, and Christopher Kin Ying [Gutachter] Leung. "Tensile behavior of high-performance cement-based composites with hybrid reinforcement subjected to quasi-static and impact loading / Ting Gong ; Gutachter: Viktor Mechtcherine, Christina Scheffler, Christopher Kin Ying Leung ; Betreuer: Viktor Mechtcherine." Dresden : Technische Universität Dresden, 2021. http://d-nb.info/1231917342/34.

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Baena, Muñoz Marta. "Study of bond behaviour between FRP reinforcement and concrete." Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/7771.

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El uso de barras de materiales compuestos (FRP) se propone como una alternativa efectiva para las tradicionales estructuras de hormigón armadas con acero que sufren corrosión en ambientes agresivos. La aceptación de estos materiales en el mundo de la construcción está condicionada a la compresión de su comportamiento estructural. Este trabajo estudia el comportamiento adherente entre barras de FRP y hormigón mediante dos programas experimentales. El primero incluye la caracterización de la adherencia entre barras de FRP y hormigón mediante ensayos de pull-out y el segundo estudia el proceso de fisuración de tirantes de hormigón reforzados con barras de GFRP mediante ensayo a tracción directa. El trabajo se concluye con el desarrollo de un modelo numérico para la simulación del comportamiento de elementos de hormigón reforzado bajo cargas de tracción. La flexibilidad del modelo lo convierte en una herramienta flexible para la realización de un estudio paramétrico sobre las variables que influyen en el proceso de fisuración.
The use of Fibre Reinforced Polymers (FRP) as reinforcement in concrete structures is considered to be a possible alternative to steel in those situations where corrosion is present. The full acceptance of FRP reinforcement in concrete construction is contingent on a complete study and comprehension of all aspects of their structural performance. This thesis investigates the bond behaviour between Fibre Reinforced Polymer (FRP) reinforcement and concrete. Two experimental programs were conducted. In the first program the role of the variables which affect the bond behaviour was studied through pull-out test. In the second program, GFRP RC members were tested in tension to study their cracking response. To conclude the thesis, a numerical model was developed to simulate the cracking behaviour of RC tensile members. Since the model was flexible enough to include any "user-defined" bond-slip law and variable materials' properties, a parametric study was conducted to analyze which are the variables that influence the cracking behaviour.

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Cáceres, Alan Renato Estrada. "Caracterização geométrica e mecânica de macrofibras poliméricas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-21062016-143713/.

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Uma grande diversidade de macrofibras poliméricas para reforço de concreto se encontram disponibilizadas hoje em dia. Por natureza estas fibras apresentam grande diversidade de características e propriedades. Estas variações afetam sua atuação como reforço no concreto. No entanto, não há normas brasileiras sobre o assunto e as metodologias de caracterização de normas estrangeiras apresentam divergências. Algumas normas definem que a caracterização do comportamento mecânico deva ser feita nos fios originais e outras que se devam utilizar métodos definidos para caracterização de materiais metálicos. A norma EN14889-2:2006 apresenta maior abrangência, mas deixa dúvidas quanto à adequação dos critérios de caracterização geométrica das fibras e não define um método de ensaio específico para sua caracterização mecânica. Assim, há a necessidade de estabelecimento de uma metodologia que permita a realização de um programa de controle de qualidade da fibra nas condições de emprego. Esta metodologia também proporcionaria uma forma de caracterização do material para estudos experimentais, o que permitiria maior fundamentação científica desses trabalhos que, frequentemente, fundamentam-se apenas em dados dos fabricantes. Assim, foi desenvolvido um estudo experimental focando a caracterização de duas macrofibras poliméricas disponíveis no mercado brasileiro. Focou-se o estudo na determinação dos parâmetros geométricos e na caracterização mecânica através da determinação da resistência à tração e avaliação do módulo de elasticidade. Na caracterização geométrica foi adotada como referência a norma europeia EN14889-2:2006. As medições do comprimento se efetuaram por dois métodos: o método do paquímetro e o método de análise de imagens digitais, empregando um software para processamento das imagens. Para a medição do diâmetro, além das metodologias mencionadas, foi usado o método da densidade. Conclui-se que o método do paquímetro, com o cuidado de esticar previamente as macrofibras, e o método das imagens digitais podem ser igualmente utilizados para medir o comprimento. Já parar determinar o diâmetro, recomenda-se o método da densidade. Quanto à caracterização mecânica, foi desenvolvida uma metodologia própria a partir de informações obtidas de outros ensaios. Assim, efetuaram-se ensaios de tração direta nas macrofibras coladas em molduras de tecido têxtil. Complementarmente, foi avaliado também o efeito do contato abrasivo das macrofibras com os agregados durante a mistura em betoneira no comportamento mecânico do material. Também se avaliou o efeito do método de determinação da área da seção transversal nos resultados medidos no ensaio de tração da fibra. Conclui-se que o método proposto para o ensaio de tração direta da fibra é viável, especialmente para a determinação da resistência à tração. O valor do módulo de elasticidade, por sua vez, acaba sendo subestimado. A determinação da área da seção da fibra através do método da densidade forneceu também os melhores resultados. Além disso, comprovou-se que o atrito das fibras com o agregado durante a mistura compromete o comportamento mecânico, reduzindo tanto a resistência quanto o módulo de elasticidade. Assim, pode-se afirmar que a metodologia proposta para o controle geométrico e mecânico das macrofibras poliméricas é adequada para a caracterização do material.
A wide variety of synthetic macrofibers for concrete reinforcement are available nowadays. By nature, these fibers exhibit great diversity of properties and characteristics. These variations affect its performance as reinforcement in concrete. However, there are no Brazilian standards on the subject and characterization methodologies available in foreign standards present divergences. Some standards define that the characterization of the mechanical behavior should be made in the original filaments and others that the test should be performed according methods for metallic materials characterization. The standard EN14889-2:2006 provides greater coverage about the subject, but leaves doubts about the suitability of the geometric characterization criteria of the fibers and does not set a specific testing method for its mechanical characterization. Thus, there is a need to establish a methodology that allows to carry out a quality control program of the fiber in the onsite conditions. This approach would also provide a way of materials characterization for experimental studies, which would allow better scientific basis of these works, which often rely exclusively on data taken from manufacturers. Thus, an experimental study focusing on the characterization of two polymer macrofibers available in Brazil was developed. The study aims at the determination of the geometrical and mechanical characteristics, such as the tensile strength and the elastic modulus. The geometric characterization was based on the prescriptions of the European standard EN14889- 2:2006. Measurements of length were made by two methods: the caliper method and digital image analysis method, employing software for image processing. For the measurement of the diameter, besides the aforementioned methodologies, the density method was also used. It is concluded that the caliper method, taking care to stretch the macrofibers previously, and the method of digital images can also be used to measure the length. To determine the diameter, it is recommended the density method. As for the mechanical characterization, a methodology was developed taking in consideration the previous information related to other tests. Thus, the direct tensile test was carried out in macrofibers glued in textile fabric frames. In addition, it was also evaluated the effect of the abrasive contact of macrofibers with the aggregates during mixing on the mechanical behavior of the material. Also, the effect of the method of determining the cross-sectional area in the results measured in fiber tensile test was evaluated. It is concluded that the proposed method for direct tensile test of the fiber is feasible, especially for tensile strength assessment. The value of the modulus of elasticity, in turn, has been underestimated. The determination of the fiber section area through the density method also gave the best results. Furthermore, it was found that the friction of the fibers with aggregate during mixing compromises the mechanical behavior reducing both strength and elastic modulus. Thus, it can be said that the proposed methodology for the geometric and mechanical control of polymer macrofibers is suitable for the material characterization.

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Hill, Meagan E. "Adding Value to Recycled Polyethylene Through the Addition of Multi-Scale Reinforcements." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1125419618.

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Hosseini, Rahimeh, and Anita Nolsjö. "The effect of reinforcement configuration on crack widths in concrete deep beams." Thesis, KTH, Betongbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208709.

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Reinforced concrete deep beams are known for applications in tall buildings, foundations and offshore structures. Deep beams are structural elements with length and height within the same magnitude and have significantly smaller thickness compared to a conventional concrete beam. Deep beams in bending have non-linear strain distribution compared to conventional beams where Bernoulli’s hypothesis is valid. Crack formation is a common problem in reinforced concrete structures, which reduce the durability of the structure. Once the concrete cracks the tension reinforcement carry the tensile forces instead of the concrete. Therefore, the design of tension reinforcement is important since the serviceability should be retained even after the structure cracks. The crack widths can be limited by using proper reinforcement and one alternative is to combine tensile reinforcement with crack reinforcement. The function of the reinforcement is to distribute the cracks over the cross section which leads to that many smaller cracks occur instead of fewer, wider cracks. Small cracks are seen as less of a problem compared to large cracks since larger cracks reduce the durability significantly. For deep beams, there is at the present no well-substantiated analysis model for how crack widths shall be calculated when having reinforcement in multiple layers with different diameters. The use of crack reinforcement in the outer bottom layer has by tradition been considered as a cost efficient way to achieve small crack widths. In this work the crack width in deep beams have been analysed using the finite element program Atena 2D. The numerical results have been verified by analytical calculations based on Eurocode 2. The aim is to achieve reduced crack widths by analysing the combination of crack- and tensile reinforcement compared to the case with tensile reinforcement only. Tensile reinforcement has a larger diameter, for example ø25 mm, and crack reinforcement has smaller diameters, often between ø10 and ø16 mm. The result from the calculations with Atena showed that there was an improvement regarding the reduction of crack widths when using crack reinforcement in combination with tensile reinforcement compared to using tensile reinforcement only. However, this improvement decreased by using reinforcement in multiple layers since a tensile reinforcement bar 1ø25 mm needed to be replaced by approximately six crack reinforcement bars 6ø10 mm in order to achieve the same total reinforcement area. The main disadvantage was that more space was required to place all reinforcement bars in the cross section, which reduced the lever arm. The reduction of the lever arm resulted in a reduced capacity for the reinforcement and the cracks might unintentionally become wider than expected. Furthermore, significant reduction of both crack widths and reinforcement stresses were obtained when the total area for a case with 7ø25 mm was increased to 9ø25 mm. The increased total area of only tensile reinforcement ø25 mm reduced the crack width more compared to using a combination of crack- and tensile reinforcement, which could simplify the construction work at building sites and minimize time consumption.
Armerade höga betongbalkar är kända för tillämpningar i höga byggnader, grundsulor och offshore konstruktioner. Höga balkar är konstruktionselement med längd och höjd i samma storleksordning och har betydligt mindre tjocklek jämfört med en konventionell betongbalk. Höga balkar i böjning har en icke-linjär töjningsfördelning jämfört med konventionella balkar där Bernoullis hypotes gäller. Sprickbildning är ett vanligt problem i armerade betongkonstruktioner, vilket minskar beständigheten hos konstruktionen. När betongbalken spricker kommer armeringen att ta upp dragkraften istället för betongen därför är utformningen av böjarmering viktig eftersom bruksgränstillståndet bör behållas även efter att konstruktionen spricker. Sprickvidderna kan begränsas genom att använda korrekt armering och ett alternativ är att kombinera kraftarmering med sprickarmering. Armeringens funktion är att sprida ut sprickorna över tvärsnittet vilket leder till att många små sprickor uppkommer i stället för färre, bredare sprickor. Små sprickor ses som ett mindre problem jämfört med stora sprickor eftersom större sprickor minskar beständigheten avsevärt. För höga balkar finns det för närvarande ingen välunderbyggd analysmodell för hur sprickvidder ska beräknas när de har armering i flera lager och med olika diametrar. Användningen av sprickarmering har traditionellt ansetts vara ett kostnadseffektivt sätt att uppnå små sprickvidder. I detta arbete har sprickvidden i höga balkar analyserats med hjälp av finita elementprogrammet Atena 2D. De numeriska resultaten har verifierats med analytiska beräkningar baserade på Eurokod 2. Syftet är att uppnå reducerade sprickvidder genom att analysera kombinationen av sprick- och kraftarmering jämfört med fallet med endast kraftarmering. Kraftarmeringen har en större diameter, till exempel ø25 mm och sprickarmering har mindre diametrar, ofta mellan ø10 och ø16 mm. Resultaten från beräkningarna i Atena visade att sprickvidderna minskade vid användning av sprickarmering i kombination med kraftarmering jämfört med användning av endast kraftarmering. Denna förbättring minskade emellertid i och med användning av armering i flera lager. En kraftarmeringsstång 1ø25 mm behöver ersättas med ungefär sex sprickarmeringsstänger, 6ø10 mm, för att uppnå samma totala armeringsarea. Den största nackdelen var att det krävdes mer utrymme för att placera alla sprickarmeringsstänger i tvärsnittet, vilket minskade hävarmen. Minskningen av hävarmen medförde en reducerad kapacitet i armeringen och sprickorna blev bredare än förväntat. Vidare erhölls signifikant reduktion av både sprickvidder och armeringsspänningar när den totala arean för ett fall med 7ø25 mm ökades till 9ø25 mm. Den ökade totalarean av endast kraftarmeringsstänger ø25 mm minskade sprickvidden mer jämfört med att använda en kombination av sprick- och kraftarmering vilket skulle kunna förenkla byggarbetet på byggarbetsplatser och minimera tidsförbrukningen.

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Faleiros, Junior José Herbet. "Procedimentos de cálculo, verificação e detalhamento de armaduras longitudinais na seção transversal em elementos protendidos." Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/4654.

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Made available in DSpace on 2016-06-02T20:09:13Z (GMT). No. of bitstreams: 1 3262.pdf: 8603825 bytes, checksum: 51c881687adbb3d6b1750785d0cfee94 (MD5) Previous issue date: 2010-08-24
The following paper presents methods of calculation, verification and detailing of prestressed longitudinal reinforcement in cross sections of elements subjected to bending conceptualizing prestressing systems and its constituent elements, as well as the development of practical examples, calculated and detailed in a didactic manner, seeking an easy understanding and learning. The present study chooses to calculate the longitudinal reinforcement at the ultimate limit state and check it out at the serviceability limit state, always following the current standards. To organize the concepts and cohesion of the information, it is necessary to discuss theoretical and conceptual foundation by assembling several authors who derive about the subject matter. In order to ensure the adoption of normative recommendations (NBR6118:2007 e NBR9062:2005), issues such as durability, cover, classes of environmental aggressiveness, combinations of calculating and limiting values of prestress are discussed. As an example, it is presented a calculation discussion from a structure tailored to different classes of environmental aggressiveness, maintaining its main features, such as: the vain, the cross section and loads. With this work we realize that the calculations are needed, since there is not a situation which determines the scaling of the longitudinal reinforcement. Lastly, we present suggestions for future papers. In order to maintain the geometric features needed to the placement of the active armor on the top edge and on the replacement of the active armor by the passive one at any percentage can only be accomplished in partial prestress. The concurrent examinations may prevent the use of certain sections, for example, when examinations on empty are exclusive, or when the moment value relative to the weight itself is small in relation to the total moment.
O presente trabalho apresenta métodos de cálculo, verificação e detalhamento de armaduras longitudinais protendidas nas seções transversais de elementos submetidos à flexão conceituando os sistemas de protensão e seus elementos constituintes, bem como, o desenvolvimento de exemplos práticos, calculados e detalhados de maneira didática, visando um fácil entendimento e aprendizado. Neste trabalho opta-se por calcular a armadura longitudinal no estado limite último e verificá-la no estado limite de serviço, seguindo sempre as normas vigentes. Para a organização dos conceitos e coesão das informações, faz-se necessária a discussão teórica e o embasamento dos conceitos através da reunião de diversos autores que discorrem sobre o assunto abordado. Pretendendo garantir a adoção das recomendações normativas (NBR6118:2007 e NBR9062:2005), são discutidas questões como durabilidade, cobrimentos, classes de agressividade ambiental, combinações de cálculo e valores limites de protensão. Na forma de exemplo, é apresentada uma discussão de cálculo a partir de uma estrutura dimensionada para variadas classes de agressividade ambiental, mantendo suas características principais, como: o vão, a seção transversal e os carregamentos. Com o trabalho percebe-se que são necessários os cálculos, pois não há uma situação determinante para o dimensionamento da armadura longitudinal. Para que se mantenham as características geométricas é necessária a colocação de armadura ativa na borda superior e na substituição da armadura ativa pela passiva em qualquer porcentagem só pode ser realizada na protensão parcial. As verificações simultâneas podem inviabilizar o uso de certas seções, por exemplo, quando as verificações em vazio são excludentes, ou quando, o valor do momento relativo ao peso próprio é pequeno em relação ao momento total. Por fim são apresentadas sugestões para trabalhos futuros.

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Arrais, Freire Reuber. "Use of fiberglass geogrids to the reinforcement of bituminous mixtures layers." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSET009.

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Cette thèse de doctorat a été développée au Laboratoire de Tribologie et Dynamique des Systèmes (LTDS) de l’Ecole Nationale des Travaux Publics de l’Etat (ENTPE), France. Il faisait partie d'un partenariat entre les sociétés françaises Afitexinov et EIFFAGE. Il a également bénéficié du soutien du programme brésilien de science sans frontières du CNPq. L'objectif de cette étude est de contribuer au développement de nouveaux géosynthétiques structurés pour le renforcement des couches bitumineuses des chaussées, ainsi que de méthodes de dimensionnement transférables vers l’ingénierie. En plus de fournir des informations utiles qui pourraient permettre la proposition d'une nouvelle méthode de conception pour les structures de chaussées renforcées. À cette fin, cinq complexes ont été conçues, quatre à deux couches et une entière, contenant le même type d’enrobé bitumineux quelle que soit la configuration. À partir des plaques à deux couches, trois ont été renforcées par la combinaison de deux géogrilles en fibre de verre (résistance à la traction maximale de 50 et 100 kN/m) avec deux émulsions comme couche d'accrochage (bitume pure et modifié par SBS). La première campagne expérimentale a porté sur la caractérisation du comportement des éprouvettes cylindriques renforcées par géogrille en fibre de verre dans le domaine de petites déformations à l'aide de essais cycliques de traction-compression. Une nouvelle méthode d'analyse d'interface a été proposée pour les essais de module complexes sur les échantillons renforcés par géogrille. D'après les résultats des tests, le comportement d'interface obtenu était viscoélastique linéaire (VEL) et il pourrait être modélisé par le modèle 2S2PD. La deuxième campagne expérimentale a porté sur la caractérisation à la charge de traction axiale monotone. Trois températures ont été combinées avec deux vitesses de déformation pour la caractérisation. Les résultats ont montré que la géogrille n'était pas très mobilisée, peut-être à cause du glissement de l'interface. La troisième campagne expérimentale concernait la caractérisation à la fatigue. Des essais de traction-compression sinusoïdale à 10°C, 10 Hz et à déformation contrôlée à différentes amplitudes ont été effectués. Les différents complexes présentaient une sensibilité distincte à la variation d'amplitude de déformation des courbes de Wöhler. Pour la méthode de dimensionnement française des chaussées, selon le paramètre ε6 obtenu dans ce travail, l'effet de renforcement de la géogrille était négligeable. La quatrième campagne expérimentale a porté sur la caractérisation sur la résistance à la propagation des fissures. L’essai four-point bending notched fracture (FPBNF) a été réalisé sur les échantillons en forme de poutre. Un dispositif de corrélation d'image numérique 3D a été utilisé pour calculer le champ de déformation pendant la propagation de la fissure ainsi que son hauteur. Un plateau de force, proportionnel à la résistance maximale à la traction de la géogrille, a été observé dans les résultats pour les échantillons renforcés grâce à la mobilisation de la géogrille lors de l'essai
This doctoral dissertation was developed at the Laboratory of Tribology and Dynamics of Systems (LTDS) at the Ecole Nationale des Travaux Publics de l’Etat (ENTPE), France. It was part of a partnership between the French companies Afitexinov and EIFFAGE Infrastructures. It also had the support of the Brazilian science without borders program from CNPq. The objective of this study is to contribute to the future development of new geosynthetics to the reinforcement of bituminous mixtures. As well as to provide useful information that could allow the proposition of new design method for reinforced pavement structures. To this end, five slab configuration was conceived, four bi-layered and one whole, containing the same type of bituminous mixture regardless of the configuration. From the bi-layered slabs, three were reinforced with the combination of two fiberglass geogrids (50 and 100kN/m maximum tensile strength) with two emulsions as tack coat (bitumen pure and modified by SBS). The last bi-layered slab was unreinforced, containing only emulsion bitumen pure on its interface. The first experimental campaign concerned the characterization of the behavior of cylindrical specimens reinforced by fiberglass geogrid at a small strain domain using cyclic tension-compression tests. A new interface analysis method was proposed for complex modulus tests of specimens reinforced by geogrid. From test results, the interface behavior obtained was linear viscoelastic (LVE) and it could be modelled by 2S2PD model. The second experimental campaign concerned characterization at monotonic axial tension loading. Three temperatures were combined with two strain rates of loading for the tension characterization. The results showed that the geogrid was not highly mobilized possibly due to a slippage in the interface. The third experimental campaign concerned fatigue characterization. Sinusoidal tension-compression tests at 10°C, 10Hz, and controlled strain at different amplitudes were carried out. The different configurations presented distinct susceptibility to strain amplitude variation of Wöhler curves. For the French design method for pavements, according to the parameter ε6 obtained in this work, the geogrid reinforcement effect was negligible. The fourth experimental campaign concerned the crack propagation resistance characterization. Four-point bending notched fracture (FPBNF) test was carried out using beams. 3D Digital Image Correlation device was used to calculate the strain field during the crack propagation as well as its tip. A force plateau, proportional to the geogrid maximum tensile strength, was observed in reinforced results related to the mobilization of the geogrid during the test

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27

Choo, Ching Chiaw. "Investigation of rectangular concrete columns reinforced or prestressed with fiber reinforced polymer (FRP) bars or tendons." Lexington, Ky. : [University of Kentucky Libraries], 2005. http://lib.uky.edu/ETD/ukycien2005d00258/ChooPhDDissertation%5FFinal.pdf.

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Анотація:

Thesis (Ph. D.)--University of Kentucky, 2005.
Title from document title page (viewed on November 7, 2005). Document formatted into pages; contains xi, 139 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 130-139).

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28

Chang, Paul, and mrpc@tpg com au. "The Mechanical Properties and Failure Mechanisms of Z-Pinned Composites." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070111.145714.

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Z-pinning is a through-thickness reinforcement technology for polymer composite materials that has been developed and commercialised over the past fifteen years. The through-thickness reinforcement of composites with thin metallic or fibrous pins aids in suppressing delamination, improving impact damage tolerance and increasing joint strength. Z-pins are applied to the composite part during its manufacture. Pins are embedded within sheets of foam and placed over the unconsolidated part. Subsequently, the foam is compacted and the pins transferred into the part, which is usually an uncured prepreg. In this manner, large numbers of pins can be inserted quickly and easily. The pinned composite is then cured using conventional processes. The use of z-pins is currently limited to several high performance composite structures, most notably Formula One racing cars and F/A-18 E/F (Superhornet) fighter aircraft, although the technology has potential applications in a d iverse variety of aerospace and non-aerospace composite structures. A limited understanding of the mechanical performance of z-pinned parts under high load and fatigue loading conditions currently hinders the application of z-pinned composites. The aim of this PhD project is to investigate the mechanical properties, strengthening mechanics and failure mechanisms of z-pinned carbon/epoxy laminates and joints. The effect of z-pin reinforcement on the tensile and flexural properties of laminates under monotonic and fatigue loading is studied. The sensitivity of these properties to the volume content and diameter of the z-pins is systematically studied by experimentation and analytical modelling. This PhD also evaluates the efficacy of z-pins in improving the load-bearing properties of carbon/epoxy lap joints. Improvements to the room temperature and elevated temperature properties of z-pinned lap joints under monotonic and fatigue tensile loading were determined. The effect of strain rate on the load-bearing properties of z-pinned lap joints was also evaluated. A further aim of the PhD project was to assess the z-pin manufacturing process and the microstructural damage caused by that process. The outcome of this study augments the analysis of the me chanical properties of z-pinned laminates and joints.

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29

Danielius, Giedrius. "Tempiamųjų gelžbetoninių elementų tempiamojo sustandėjimo eksperimentiniai ir teoriniai tyrimai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140613_123314-48778.

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Dėl sąveikos su armatūros strypais iš esmės pakinta tempiamojo betono fizikinis įtempių ir deformacijų būvis, todėl taikyti vientiso tempiamojo betono įtempių ir deformacijų diagramas negalima. Armuotojo betono atveju šios diagramos yra pakeičiamos vadinamosiomis tempiamojo sustandėjimo įtempių ir deformacijų diagramomis, tačiau iki šiol nėra priimta bendro metodo, kaip jas reikėtų apskaičiuoti. Baigiamojo magistro darbo tikslas – pasiūlyti tempiamojo betono įtempių ir deformacijų fizikinį modelį. Baigiamajame darbe atlikta kritinė literatūros šaltinių betono tempiamojo sustandėjimo tematika analizė. Atlikti tempiamųjų gelžbetoninių elementų eksperimentiniai ir skaitiniai tyrimai. Literatūros šaltiniuose aptiktų eksperimentinių tyrimų rezultatai palyginti su atliktais eksperimentiniais ir skaitiniais tyrimais. Pagal atrinktus duomenis išvestas tempiamojo betono įtempių ir deformacijų fizikinis modelis bei atlikta jo statistinė analizė. Baigiamąjį magistro darbą sudaro įvadas, trys skyriai, išvados bei literatūros sąrašas. Darbo apimtis – 64 puslapiai. Tekste pateikta 50 formulių, 41 paveikslas ir 10 lentelių. Rašant darbą remtasi 30 literatūros šaltinių.
Interaction between concrete and reinforcement changes the way tensile concrete behaves thus the stress–strain relationship for solid tensile concrete cannot be applied anymore. In the case of reinforced concrete, these graphs are changed with so–called tension stiffening diagrams but until now there has been no confirmed method that would allow us to determine it. The aim of the master thesis is to propose a physical model for stress–strain relationship of tensile concrete. In the master thesis a close analysis of a number of scientific articles about tension stiffening has been done. Experimental and numerical research for tensile reinforced concrete members has been performed. The data found in scientific articles has been compared with the data of experimental and numerical research. Based on the results of experimental research a physical model for stress–strain relationship of tensile concrete has been proposed, also a statistical accuracy analysis of the model has been performed. The master thesis consists of introduction, three chapters, conclusions and references. Total number of pages is 64. Thesis includes 50 equations, 41 figures and 10 tables. Paper refers to 30 scientific source materials.

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Ruellan, Benoît. "Fatigue of natural rubber at different temperatures : reinforcement due to strain-induced crystallization and modelling the non-linear damage evolution." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S058.

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Анотація:

Cette thèse de doctorat s'intéresse au comportement en fatigue du caoutchouc naturel (CN). Les CN présentent des propriétés physiques extraordinaires, typiquement l'habilité de cristalliser sous tension qui est responsable de leur haute résistance en fatigue. La cristallisation sous tension (CST, en français) est un phénomène hautement thermosensible. Mieux comprendre comment la CST renforce la durée de vie et comment la température altère cette propriété est donc un point clef afin d'améliorer la durabilité des élastomères. La présente thèse est divisée en trois parties. La première est dédiée à l'investigation du comportement en fatigue du CN à 23°C, elle confirme que la CST est responsable d'un renforcement en durée de vie. Par ailleurs, une analyse fractographique est menée afin de mieux comprendre les mécanismes de renforcement. Parmi les différents résultats obtenus, de nouveaux éléments sur le phénomène de formation de stries de fatigue sont proposés. La seconde partie traite de l'effet de la température sur le renforcement induit par la CST sous des chargements non-relaxants. De manière surprenante, un renforcement en durée de vie s'opère encore à 90°C, bien que la CST soit admise comme étant significativement atténuée, voire annulée à température élevée. En revanche, les effets de la CST disparaissent à 110°C. La troisième partie présente la construction d'un modèle de prédiction de durée de vie pour des chargements à amplitude variable. Le modèle prend en compte le renforcement en durée de vie induit par la CST, l'effet de la température ainsi que la non-linéarité de l'endommagement
The present thesis is dedicated to the investigation of the fatigue behavior of natural rubber (NR) under fatigue loadings. Natural rubbers exhibit extraordinary physical properties, typically the ability to crystallize under tension that is assumed to be responsible for their high fatigue resistance. Strain-induced crystallization (SIC) is a highly thermosensitive phenomenon. Better understanding how SIC reinforces the fatigue life and how temperature affects this property is therefore a key point to improve the durability of rubbers. The present thesis is divided in three parts. The first one is dedicated to the investigation of the fatigue behavior of NR at 23°C and confirms that SIC is responsible for a lifetime reinforcement. Furthermore, a post-mortem analysis is carried to better understand the reinforcement mechanisms. Among the different results obtained, new elements are provided on the fatigue striation phenomenon. The second part addresses the effect of temperature on the SIC-induced reinforcement under non-relaxing loadings. Surprisingly, a lifetime reinforcement still occurs at 90°C although SIC is assumed to be significantly attenuated if not cancelled at elevated temperatures. No SIC effect was observed at 110°C. The third part deals with the construction of a lifetime prediction model for variable loading amplitudes. This model accounts for the lifetime reinforcement due to SIC and the effect of temperature, as well as for non-linear damage

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Niedoba, Jakub. "Experimentální a numerická analýza zesílení železobetonových prvků." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-433485.

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Анотація:

This master‘s thesis deals with the behaviour of strengthened reinforced concrete beams. The aim was to evaluate different types of strengthening in comparison not only with each other, but also with the reference beam. Three reinforced concrete beams were fabricated for the purpose of the thesis. The first served as a reference beam, the second was strengthened with carbon lamella glued to the lower edge of the reinforced concrete beam, and the last one was strengthened with unbonded post-tensioning system. Subsequently, they were all loaded by a four-point bending. An evaluation was then carried out which shows that the two strengthened reinforced concreate beams resist the load much better than the reference beam. In the conclusion, different utilization possibilities of both methods are listed, as well as the disadvantages that must be taken into account when designing.

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32

Weber, Jozef. "Tribuna fotbalového stadionu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265685.

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Анотація:

The aim of the diploma thesis was to design the precast reinforced concrete prefabricated structures of the football tribune. It was modernized sports center in Brno. According to the investor was determined the shape of the football tribune. It was compiled the design documentation. For the calculation of inner strengths was used the software Dlubal RFEM, which operates on the Finite Element Method - FEM. All elements have been designed for ultimate and serviceability limit state. My thesis contains textual part, inner strengths, static calculations, drawing documentation of composition of structure, drawing documentation of reinforcement and design documentation of the object.

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Sachr, Jiří. "Asfaltové vrstvy s výztužnými sklovláknitými geomřížemi." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392053.

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This diploma thesis deals with the use of glass fiber geogrids and geocomposites in road construction. The reinforcement elements are inserted between the wearing and binder asphalt layer. This diploma thesis summarizes the knowledge connected with reinforcing of asphalt roads using glass fiber. It examines the effect of reinforcing fiberglass elements on the resistance of asphalt layers loaded with traffic. At the same time, it deals with the application of a various amount of tack coat and subsequent behavior of the asphalt layers. In this work, laboratory tests of bond strength between layers on cores and four-point bending were performed.

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34

Jesse, Dirk. "Tragverhalten von textilbewehrtem Beton unter zweiaxialer Zugbeanspruchung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-69387.

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Анотація:

Das Trag- und Verbundverhalten textiler Bewehrungen wurde in den vergangen Jahren umfassend experimentell untersucht. Die dabei gewonnenen Erkenntnisse stützen sich jedoch fast ausschließlich auf einaxiale Beanspruchungszustände. Grundsätzlich können aus dem Vergleich von Versuchen an Rovings und an textilen Bewehrungsstrukturen Rückschlüsse auf den Einfluss der Quer- und Stützfäden und der verschiedenen Bindungstechniken auf das einaxiale Tragverhalten von Textilbeton getroffen werden. Offen bleibt jedoch, inwieweit sich die gefundenen Gesetzmäßigkeiten auf mehraxiale Beanspruchungssituationen übertragen lassen. Dadurch werden Fragen bezüglich des Tragverhaltens textiler Bewehrungen unter mehraxialen Zugbeanspruchungen aufgeworfen, welche die Motivation für die vorliegende Arbeit liefern. Die hierzu durchgeführten experimentellen Untersuchungen umfassen 84 Einzelversuche und wurden in einem speziell für zweiaxiale Zugbeanspruchungen entwickelten Versuchsaufbau durchgeführt. Als textile Bewehrungen kamen zwei verschiedene Gelegearten aus AR-Glas und Carbon zum Einsatz. Die Ergebnisse konnten die bisher ausschließlich an einaxialen Dehnkörpern gewonnenen Erkenntnisse über das Tragverhalten textiler Bewehrungen grundsätzlich bestätigen. Für den Übergang von Zustand I zum Zustand II konnte eine Abhängigkeit der Erstrissspannung vom Spannungsverhältnis nachgewiesen werden. Die Merkmale der Zustände IIa und IIb zeigen hingegen keine signifikante Abhängigkeit vom Verhältnis aus Längs- und Querzugspannung. Darüber hinaus haben offenbar durch Querzug induzierte bewehrungsparallele Risse keine maßgeblichen Auswirkungen auf das Verbundverhalten der Rovings in Längsrichtung. Eine wesentliche Erkenntnis aus den biaxialen Zugversuchen mit Carbon betrifft den Einfluss der Welligkeit. Es wurde deutlich, dass der Abbau der Welligkeit in beschichteten textilen Bewehrungen hochgradig lastabhängig ist. In zahlreichen Versuchen mit Carbon kam es innerhalb des Zustands IIb zu Delamination, einem bisher in diesem Umfang nicht beobachteten Effekt. Die Erkenntnisse hinsichtlich des Abbaus der Welligkeit wurden im Anschluss auf das Tragverhalten von AR-Glas übertragen und führten zu einer Neubewertung des bei AR-Glas beobachteten Steifigkeitsdefizits im Zustand IIb. Weiterhin wurde der Einfluss der Orientierung der Bewehrung unter einaxialer Beanspruchung an scheibenartigen Probekörpern untersucht. Es zeigte sich, dass die untersuchten Bewehrungen aus AR-Glas hinsichtlich der Tragfähigkeit bei schiefwinkliger Beanspruchung deutlich unempfindlicher reagieren als Bewehrungen aus Carbon. Für die Reduktion der effektiven Faserbruchspannungen wurde ein mathematisches Modell vorgestellt, welches eine getrennte Beschreibung der geometrischen Einflüsse sowie alle sonstigen, die Faserbruchspannung reduzierenden Effekte erlaubt
The load bearing and bond behaviour of textile reinforcements has been comprehensively studied experimental in recent years. The findings are based almost exclusively on uniaxial loading. Generally, from the comparison of tests on rovings and fabrics conclusions can be drawn about the influence of transverse and supporting threads and different binding patterns on the uniaxial load-bearing behaviour. However, it remains open, to what extend the found principles are applicable to multi-axial loading situations. This raises questions about the load bearing behaviour under multi-axial tension loading, which provide motivation for this work. For the experimental studies on 84 specimens a specially developed test setup for biaxial tensile loading was used. Two different types of textile reinforcements made from AR-glass and carbon fibres were examined. The results generally approve the findings on the structural behaviour of textile reinforcements exclusively derived from uniaxial tests. A relationship between first cracking stress level and biaxial stress ratio has been found. The characteristics of the cracking phases and during stabilized cracking, however, show no significant dependencies on the ratio of longitudinal and transverse tensile stresses. Furthermore, parallel cracks induced by transverse tensile stresses have no significant impact on the bond behaviour of longitudinal rovings. An essential result from biaxial tensile tests with carbon is the strong influence of waviness. It became clear that the reduction of waviness in coated textile reinforcement is highly load-dependent. In numerous experiments with carbon reinforcement delamination occurred during stabilized cracking – an effect, that has been observed in this large scale for the first time. The findings regarding the reduction of the waviness were subsequently applied to AR-glass and led to a revaluation of the known stiffness deficit in the phase IIb. Furthermore, the influence of reinforcement orientation has been studied on discoidal specimens under uni-axial loading. It was found that the load bearing capacity of carbon reinforcement is much more sensible to load orientation than AR-glass. A mathematical model was presented, which allows the separate description of geometric factors and as well as all other effects that reduce the fibre tensile strength

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35

Čípek, Luboš. "Most přes řeku Jevišovku." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-412918.

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This thesis focuses on design and assessment of load-bearing construction of a bridge over Jevišovka river at road I/53 near Lechovice. The bridge was designed as a trapezoidal cross-section slab. This solution was chosen from three sketch eventualities. The work includes an implementing engineering report, construction process report and report about static-analysis, the attachments include the sketch, vizualization, drawings, component drawing, construction process and the static-analysis of this structure. Computing of internal forces was performed by computational software Scia Engineer 17.

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Ben, Ramdane Camélia. "Etude et modélisation du comportement mécanique de CMC oxyde/oxyde." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0077/document.

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Анотація:

Les CMC oxyde/oxyde sont de bons candidats pour des applications thermostructurales. Le comportement mécanique et les mécanismes d’endommagement de deux composites alumine/alumine à renforts tissés bi- et tridimensionnels ont été étudiés et comparés. La microstructure de ces CMC à matrice faible a été caractérisée à partir de porosimétrie et de CND, tel que thermographie IR, scan ultrasonore et tomographie X, ce qui a permis de mettre en évidence la présence de défauts initiaux. Le comportement mécanique en traction, ainsi qu’en compression dansle cas du CMC à renfort bidimensionnel, dans la direction des fibres ainsi que dans la direction ±45°, aété étudié à température ambiante. Afin d’exploiter pleinement ces essais, nous avons eu recours à plusieurs méthodes d’extensométrie et de suivi d’endommagement, telles que la thermographie IR et l’émission acoustique. Les propriétés mécaniques à rupture ainsi que le module de Young du CMC à renfort bidimensionnel développé à l’Onera se sont avérées supérieures à celles disponibles dans la littérature. Les mécanismes d’endommagement des matériaux ont été déterminés à partir d’observations post mortem au MEB et d’essais in situ dans un MEB, ce qui a permis d’évaluer la nocivité des défauts initiaux. Enfin, l’étude du comportement mécanique de ces composites a permisde proposer un modèle d’endommagement tridimensionnel qui permettra de poursuivre le développement de ces matériaux grâce à du calcul de structure. A l’issue de cette thèse, des pistes d’amélioration des procédés d’élaboration et de choix d’instrumentation à utiliser pour les futures études, notamment en ce qui concerne le suivi d’endommagement, ont également été proposées
Oxide/oxide CMCs are good candidates for thermostructural applications. Themechanical behaviour and damage mechanisms of two alumina/alumina composites with two andthree dimensional woven reinforcements were studied and compared. The microstructure of theseweak matrix CMCs was characterized by porosimetry and NDT methods, such as IR thermography,ultrasound scanning and X-ray tomography, which highlighted initial defects. The mechanicalbehaviour was studied through tensile tests, as well as compression tests in the case of the twodimensionalreinforced CMC. These tests were conducted at room temperature, in the fibres directionsand in the ±45° direction. In order to fully exploit these tests, several extensometry and damagemonitoring methods, such as IR thermography and acoustic emission, were used. Young’s moduli andmaximum stresses and strains of the two-dimensional reinforced CMC developed at Onera appearedto be higher than those available in the literature. The damage mechanisms of the materials weredetermined by post mortem SEM observations and in situ testing in a SEM, which made it possible toassess the nocivity of initial defects. Studying the mechanical behaviour of these composites finallyenabled the development of a three-dimensional damage model that will facilitate the furtherdevelopment of such materials, through finite element analysis. Finally, some improvements regardingthe manufacturing processes and the instrumentation for damage monitoring were suggested forfuture studies

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Štramberský, Martin. "Návrh předpjaté nádrže." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226967.

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The matter of this diploma thesis is a static storage tank for petroleum substances, the study of a solution for appropriate shape of shell and its effort to dihedral for roofing, and the study of effect of the storage of inner roofs walls of the tank to the size of the internal forces. The internal walls are carried out by the method of finite elements in the engineering program Scia Engineering 2013 and on the basis of it, designing of the framing sections of the tank. There is a calculation part of the lower horizontal bias wreaths of the shell and internal supporting wall. All the components are assessed on the 1st limit state of the load-bearing capacity and the 2nd limit state of the application (emergence cracks, limiting voltage in the concrete and a prestressing steel). The existing external wall is assessed only on the marginal status load of carrying capacity. The part of diploma thesis is also drawing documentation, accompanying report and technical report. The goal of the diploma thesis was to design the tank without an occurrence of the cracks in the concrete so as the vertical wall was prestressing only in the horizontal direction and the optimal proposal roof tanks as an addition.

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38

TSAI, MIN-HSIU, and 蔡旻修. "Effects of Reinforcement Length on Deformation Characteristics and Reinforcement Tensile Force of Geosynthetics-Reinforced Soil Structures." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/734488.

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Анотація:

碩士
國立雲林科技大學
營建工程系
107
In this study, a series of plane strain model tests on wrap-faced geogrid-reinforced soil (GRS) retaining wall were conducted to investigate the effects of reinforcement length on its deformation characteristics and the mobilized reinforcement tensile force. Two types of coarse-grained soils, namely, sand and gravel, were adopted as the backfills of GRS retaining wall. A PET geogrid with its nominal strength 150 kN × 30 kN was used. The dimensions of the model wall were 172.6 cm (length) × 80 cm (width) × 112 cm (height). A strip footing of 30 cm wide, having its setback distance equal to 50cm was located on the surface of backfill to resist the applied vertical load during model test. By using photogrammetric analysis method, the deformation patterns of soil mass, the lateral movement of facing and the progressive failure process of soil based on the calculated shear strain contours were also obtained. In this study, the tensile strain of geogrid based on the measured data of the strain gauge attached on the surface were proved to be identically the same as those value obtained from standard method of ASTM D6637. The test results show that under the same vertical settlement of footing, the longer length of geogrid, the higher applied footing bearing vertical stress. Under the same vertical displacement of footing, the lateral movement of facing of GRS retaining wall with shorter length of geogrid was larger than the same type GRS wall but having longer geogrid in the first layer. The maximum tensile strain was found to be at the intersection point of the shear zone for all GRS walls, but the maximum value in gravel is larger than that in sand. To sum up, the ultimate bearing capacity, the lateral deformation of facing, the tensile strain of geogrid and the deformation pattern of soil were found to be significantly influenced by the length of geogrid.

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39

PAMPANG, JUSIEANDRA PRIBADI, and 朱文漢. "Predicting Tensile Loads in Reinforcement for Geosynthetic-Reinforced Soil Structures by Evolutionary Metaheuristic Intelligence Model." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/17634511461913918450.

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Анотація:

碩士
國立臺灣科技大學
營建工程系
102
Accurately estimating reinforcement tensile loads is crucial for evaluating the internal stabilities of geosynthetic-reinforced soil (GRS) structures. This study developed an evolutionary metaheuristic intelligence model for efficiently and accurately estimating reinforcement loads. The proposed model improves the prediction capability of the firefly algorithm (FA) by integrating intelligent components, namely chaotic maps, adaptive inertia weight, and Lévy flight. The enhanced FA is then used to optimize the hyperparameters for support vector regression (SVR) model. The proposed model was validated using a database of 15 wall case studies (totally 94 data points) via cross-validation algorithm and hypothesis test. The method was then compared with conventional prediction methods in terms of accuracy in predicting reinforcement tensile loads in GRS structures. The validation results showed that the proposed model had superior accuracy and mean absolute percentage errors below 7%. Moreover, comparison with the baseline models and prior literature indicated that the evolutionary metaheuristic intelligence model had a significant improvement of 26.15% to 96.90% in root mean square errors. This study validates the effectiveness of the proposed model of reinforcement tensile loads and its feasibility for facilitating early designs of construction structures.

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40

Kuan, Chi-Tung, and 官己棟. "The Analysis for the Tensile Strength and the Vertical Structure Reinforcement of PC/ABS Blend Materials Used as Automotive Skin Panels." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/43846423874825485747.

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Анотація:

碩士
中原大學
機械工程研究所
96
PC/ABS (Polycarbonate/Acrylonitrile Butadiene Styrene Copolymer) blend material, with advantages of light-weight and good sustenance under both heat and impact, has been widely applied in automobile, electronic technology, and defense industries. In this thesis, the study focuses on the application of the PC/ABS hive structure in building automobiles. Such PC/ABS hive structure can further reduce total construction weight of automobile to save energy. In this study, the CAD tool CATIA is applied to help the numerical analysis. The module Generative Structure Analysis of CATIA uses the finite element method to analyze static load of the PC/ABS hive structures with different hive sizes and heights. It turns out that the most important factor affects static load of the hive structure is the dimension of height: Increasing the height of the hive structure can obviously reduce the displacement of the structure under static load. Comparing with PC/ABS blend material structured as hives, the bare PC/ABS blend material needs three times height to achieve the same result in displacement. This study concludes that it is workable to replace the traditional metal panel used for Body In White in automobile by applying the PC/ABS blend material structured as hives plus vertically structural reinforcement for ejection forming. Furthermore, this study compares the hive structure with the popular 0.7 mm thick SPCD panel in automobile and shows the optimized width and height. The research also provides the static load analysis under different hive structures and could be helpful for designing Body In White.

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41

Liu, Jing-Zhong, and 柳景仲. "THE SPLICE STRENGTHS OF REINFORCEMENT IN TENSION POST FIRE." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/32845008492211974095.

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Анотація:

碩士
國立臺灣科技大學
營建工程技術學系
83
This research is to investigate the residual bond strengths of tensile deformed bars post fire. This test program consists of three parts which are the beam tests in the fire, the static tests of beams and material tests. The main purpose of this tests is to investigate the degredation of bond strengths and flexural stiffnesses of the beams post fire. The test variables included the water-cementitious ratio, the amount of the transverse reinforcement in the spliced region , and the imposed beam loads. Fifteen beam specimens were tested. Four of them were control beams and eleven of them were heated according to BS476 standard temperature rise curve with the 3-hour duration in fire. Test results indicate that the bond strengths of the beams of the normal strength concrete after fire could be decreased of 45 percent on the average and that the bond strengths of the beams of the high performance concrete could be decreased of 50 percent on the average. The flexural stiffness of the beams of the normal strength concrete after fire could be decreased of 62 percent on the average and that the flexural stiffness of the beams of the high performance concrete could be decreased of 50 percent on the average.

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42

Ju, Jin-Hung, and 朱敬寰. "THE SPLICE STRENGTHS OF REINFORCEMENT IN TENSION UNDER FIRE." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/66687561159784753074.

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Анотація:

碩士
國立臺灣科技大學
營建工程技術學系
83
This research is to investigate whether the splice strength conforming toACI 318-89 Code would survive the tests of the thermal and flexural loads simultaneously. The reinforced concrete beams with lap splices in the constant moment region were heated in the furnace by the BS 476 time-temperature curve. The residual strengths and the failure modes of the beams post fire are also reported. The test variables included the water-cementitious ratio, the amount of the transverse reinforcement in the spliced region, and the amount of flexural loads under fire test. Fifteen beam specimens were tested. Two of them were control units and the others were heated according to BS 476 standard temperature rise curve with the 3-hour duration in fire. Test results indicate that the splice length designed by ACI 318-89 Code and with transverse reinforcement can survive the 3-hour fire test with simultaneous service load. The residual strengths of beams with high-performace concrete are larger than those of beams with normal strength concrete. The failure mode post fire is the bond splitting failure for most specimens.

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43

Deluce, Jordon Robert. "Cracking Behaviour of Steel Fibre Reinforced Concrete Containing Conventional Steel Reinforcement." Thesis, 2011. http://hdl.handle.net/1807/29523.

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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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44

Liau, Yi-Shin, and 廖奕信. "Finite Element Analysis of Fiber-Reinforced Isolators with Tension-only Reinforcements." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/xtuwk9.

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Анотація:

碩士
國立臺灣科技大學
營建工程系
94
Not only does the laminated rubber isolator have the high vertical stiffness, high bending stiffness, but has the low lateral stiffness. As a result, it can extend the structural period and reduce the input lateral load. Generally, the reinforcing material for laminated rubber isolators is steel plates. In contrast to the steel-reinforced isolator, the fiber-reinforced isolator is significantly lighter, cheaper and easier in the manufacturing processes. This research mainly focuses on using the finite element method to analyze the infinite-strip-shaped fiber-reinforced isolators subjected to pure bending deformation and shear deformation. The stress and deformation of the isolators under the various parameters will be fully discussed. Because the material characteristic of the fiber is tension-only reinforcements, so the research analyze by the nonlinear analysis. The results will be compared with the linear analysis, in which the fiber can bear tension and compression stress. The results of the finite element analysis show that, when the vertical displacement is larger or equal to the slope of the isolator, the nonlinear analysis will equal to the linear analysis. In the bending analysis, the axial force and bending moment increase along with the increasing the Poisson’s ratio and shape factor for the constant value of vertical displacement and slope of the isolator. Furthermore, they decrease along with the increasing the stiffness ratio of the elastic layer and the reinforcement under the same circumstance. In the shear analysis, horizontal stiffness increases along with the Poisson’s ratio and shape factor, and decreases along with increasing the stiffness ratio of the isolator. The rotation in the middle of the isolator decreases according to increasing the Poisson’s ratio and shape factor, and increases according to increasing the stiffness ratio.

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45

Utomo, Panji, and 陳虎豪. "EVALUATION OF VARIOUS DESIGN METHODS FOR PREDICTING REINFORCEMENT TENSION WITHIN GEOSYNTHETIC-REINFORCED SOIL STRUCTURES." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/m4744y.

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Анотація:

碩士
國立臺灣科技大學
營建工程系
99
Proper estimation of reinforcement tension is a key to evaluate the internal stabilities of Geosynthetic-Reinforced Soil (GRS) structures. Prediction methods for reinforcement tension within GRS structures in current practice can be categorized into two approaches: force-equilibrium-based approach (i.e. earth-pressure-based method and limit equilibrium method) and deformation-based approach (i.e. Kstiffness method and finite element method). Until today, the effects of these methods have not been extensively examined and compared yet. In this paper, each of methods will firstly be introduced and the advantages and disadvantages of each method will be discussed. Afterward, two cases of GRS structures are used to examine the prediction of reinforcement tension by the aforementioned methods. Comparison results indicate the earth-pressure-based method and limit equilibrium over predict the reinforcement tension. The finite element method agrees well with the measured data, but the K-stiffness method shows an obvious under prediction under surcharging conditions.

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46

Noel, Martin. "Behaviour of Post-Tensioned Slab Bridges with FRP Reinforcement under Monotonic and Fatigue Loading." Thesis, 2013. http://hdl.handle.net/10012/7647.

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The introduction of fibre-reinforced polymers (FRPs) to the field of civil engineering has led to numerous research efforts focusing on a wide range of applications where properties such as high strength, light weight or corrosion resistance are desirable. In particular, FRP materials have been especially attractive for use as internal reinforcement in reinforced concrete (RC) structures exposed to aggressive environments due to the rapidly deteriorating infrastructure resulting from corrosion of conventional steel reinforcement. While FRPs have been successfully implemented in a variety of structural applications, little research has been conducted on the use of FRP reinforcement for short span slab bridges. Furthermore, the behaviour of FRP-RC flexural members cast with self-consolidating concrete (SCC) is largely absent from the literature. The present study investigates the behaviour of an all-FRP reinforcement system for slab bridges which combines lower cost glass FRP (GFRP) reinforcing bars with high performance carbon FRP (CFRP) prestressed tendons in SCC to produce a structure which is both cost-efficient and characterized by excellent structural performance at the serviceability, ultimate and fatigue limit states. An extensive experimental program comprised of 57 large or full-scale slab strips was conducted to investigate the effects of reinforcement type, reinforcement ratio, prestressing level and shear reinforcement type on the flexural performance of slab bridges under both monotonic and fatigue loading. The proposed reinforcement system was found to display excellent serviceability characteristics and high load capacities as well as significant deformability to allow for sufficient warning prior to failure. Lastly, the use of post-tensioned CFRP tendons limited the stresses in the GFRP reinforcing bars leading to significantly longer fatigue lives and higher fatigue strengths compared to non-prestressed slabs. Analytical models were used to predict the behaviour of the slab bridge strips at service and at ultimate. Where these models failed to accurately represent the experimental findings, simple modifications were proposed. The results from ancillary tests were also used to modify existing analytical models to predict the effects of fatigue loading on the deflection, crack width, shear resistance and flexural capacity of each of the tested slabs.

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47

Jesse, Dirk. "Tragverhalten von textilbewehrtem Beton unter zweiaxialer Zugbeanspruchung: Bearing Behaviour of Textile Reinforced Concrete Under Biaxial Tension Loading." Doctoral thesis, 2010. https://tud.qucosa.de/id/qucosa%3A25591.

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Das Trag- und Verbundverhalten textiler Bewehrungen wurde in den vergangen Jahren umfassend experimentell untersucht. Die dabei gewonnenen Erkenntnisse stützen sich jedoch fast ausschließlich auf einaxiale Beanspruchungszustände. Grundsätzlich können aus dem Vergleich von Versuchen an Rovings und an textilen Bewehrungsstrukturen Rückschlüsse auf den Einfluss der Quer- und Stützfäden und der verschiedenen Bindungstechniken auf das einaxiale Tragverhalten von Textilbeton getroffen werden. Offen bleibt jedoch, inwieweit sich die gefundenen Gesetzmäßigkeiten auf mehraxiale Beanspruchungssituationen übertragen lassen. Dadurch werden Fragen bezüglich des Tragverhaltens textiler Bewehrungen unter mehraxialen Zugbeanspruchungen aufgeworfen, welche die Motivation für die vorliegende Arbeit liefern. Die hierzu durchgeführten experimentellen Untersuchungen umfassen 84 Einzelversuche und wurden in einem speziell für zweiaxiale Zugbeanspruchungen entwickelten Versuchsaufbau durchgeführt. Als textile Bewehrungen kamen zwei verschiedene Gelegearten aus AR-Glas und Carbon zum Einsatz. Die Ergebnisse konnten die bisher ausschließlich an einaxialen Dehnkörpern gewonnenen Erkenntnisse über das Tragverhalten textiler Bewehrungen grundsätzlich bestätigen. Für den Übergang von Zustand I zum Zustand II konnte eine Abhängigkeit der Erstrissspannung vom Spannungsverhältnis nachgewiesen werden. Die Merkmale der Zustände IIa und IIb zeigen hingegen keine signifikante Abhängigkeit vom Verhältnis aus Längs- und Querzugspannung. Darüber hinaus haben offenbar durch Querzug induzierte bewehrungsparallele Risse keine maßgeblichen Auswirkungen auf das Verbundverhalten der Rovings in Längsrichtung. Eine wesentliche Erkenntnis aus den biaxialen Zugversuchen mit Carbon betrifft den Einfluss der Welligkeit. Es wurde deutlich, dass der Abbau der Welligkeit in beschichteten textilen Bewehrungen hochgradig lastabhängig ist. In zahlreichen Versuchen mit Carbon kam es innerhalb des Zustands IIb zu Delamination, einem bisher in diesem Umfang nicht beobachteten Effekt. Die Erkenntnisse hinsichtlich des Abbaus der Welligkeit wurden im Anschluss auf das Tragverhalten von AR-Glas übertragen und führten zu einer Neubewertung des bei AR-Glas beobachteten Steifigkeitsdefizits im Zustand IIb. Weiterhin wurde der Einfluss der Orientierung der Bewehrung unter einaxialer Beanspruchung an scheibenartigen Probekörpern untersucht. Es zeigte sich, dass die untersuchten Bewehrungen aus AR-Glas hinsichtlich der Tragfähigkeit bei schiefwinkliger Beanspruchung deutlich unempfindlicher reagieren als Bewehrungen aus Carbon. Für die Reduktion der effektiven Faserbruchspannungen wurde ein mathematisches Modell vorgestellt, welches eine getrennte Beschreibung der geometrischen Einflüsse sowie alle sonstigen, die Faserbruchspannung reduzierenden Effekte erlaubt.
The load bearing and bond behaviour of textile reinforcements has been comprehensively studied experimental in recent years. The findings are based almost exclusively on uniaxial loading. Generally, from the comparison of tests on rovings and fabrics conclusions can be drawn about the influence of transverse and supporting threads and different binding patterns on the uniaxial load-bearing behaviour. However, it remains open, to what extend the found principles are applicable to multi-axial loading situations. This raises questions about the load bearing behaviour under multi-axial tension loading, which provide motivation for this work. For the experimental studies on 84 specimens a specially developed test setup for biaxial tensile loading was used. Two different types of textile reinforcements made from AR-glass and carbon fibres were examined. The results generally approve the findings on the structural behaviour of textile reinforcements exclusively derived from uniaxial tests. A relationship between first cracking stress level and biaxial stress ratio has been found. The characteristics of the cracking phases and during stabilized cracking, however, show no significant dependencies on the ratio of longitudinal and transverse tensile stresses. Furthermore, parallel cracks induced by transverse tensile stresses have no significant impact on the bond behaviour of longitudinal rovings. An essential result from biaxial tensile tests with carbon is the strong influence of waviness. It became clear that the reduction of waviness in coated textile reinforcement is highly load-dependent. In numerous experiments with carbon reinforcement delamination occurred during stabilized cracking – an effect, that has been observed in this large scale for the first time. The findings regarding the reduction of the waviness were subsequently applied to AR-glass and led to a revaluation of the known stiffness deficit in the phase IIb. Furthermore, the influence of reinforcement orientation has been studied on discoidal specimens under uni-axial loading. It was found that the load bearing capacity of carbon reinforcement is much more sensible to load orientation than AR-glass. A mathematical model was presented, which allows the separate description of geometric factors and as well as all other effects that reduce the fibre tensile strength.

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