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1
Ozdemir, Gokhan. "Mechanical Properties Of Cfrp Anchorages." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605890/index.pdf.
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Due to inadequate lateral stiffness, many reinforced concrete buildings are highly damaged or collapsed in Turkey after the major earthquake. To improve the behavior of such buildings and to prevent them from collapse, repair and/or strengthening of some reinforced concrete elements is required. One of the strengthening techniques is the use of CFRP sheets on the existing hollow brick masonry infill. While using the CFRP sheets their attachment to both structural and non-structural members are provided by CFRP anchor dowels. In this study, by means of the prepared test setup, the pull-out strength capacities of CFRP anchor dowels are measured. The effects of concrete compressive strength, anchorage depth, anchorage diameter, and number of fibers on the tensile strength capacity of CFRP anchor dowel are studied.
2
Milne, Grant Dean. "Condition monitoring & integrity assessment of rock anchorages." Thesis, University of Aberdeen, 1999. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=219062.
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Current methods for assessing the integrity of ground anchorages during service are primarily restricted to monitoring by load cells or load lift-off testing. Both are expensive and lift-off testing is time consuming and can damage the anchorage construction below the anchor head. Hence, only typically 5-10% of anchorages are monitored in service. As a result, The Institution of Civil Engineers reported that non-destructive test methods for ground anchorages need to be developed as a high priority (ICE, 1992). The Universities o f Aberdeen and Bradford have been conducting research since 1986 to investigate the response o f rock anchorages to dynamic loading arising from blasting operations. Full scale field trials were conducted during the construction of two tunnels in North Wales. An important finding from the research revealed that certain characteristics of the dynamic response of a rock bolt resulting from blasting operations, were similar for different blast sequences. This indicates that the dynamic response o f an anchorage system is dependant on the construction of the anchorage and the characteristics of the co-vibrating rock mass. Consequently, the University of Aberdeen has developed a new non-destructive condition monitoring and integrity assessment system for ground anchorages (GRANIT ™). A range of patent applications have been successful world-wide and the system has been exclusively licensed to AMEC Civil Engineering Limited. The system operates by applying an axial tensile impact load to the free end of an intact anchorage immediately after installation. The resulting vibrational response is monitored by an accelerometer, located at the anchorage head, which produces a datum signature for that anchorage. The condition of the anchorage is then inferred by comparing subsequent response signatures with the datum. A change in the signature indicates that there may be a potential change in the integrity of the anchorage. Artificial Intelligence systems are employed to compare response signatures. As part of the research programme, the author conducted commissioning tests on small scale laboratory test rigs and was responsible for the development of a prototype non-destructive test system, which included a means of applying an impact load and recording the vibrational response. In addition, the author conducted full scale laboratory tests and field trials to investigate the effect of prestress on the dynamic response of ground anchorage systems. As a result, the prototype non-destructive test system has been employed to successfully predict the amount of load within an anchorage installation.
3
Starkey, Andrew J. "Condition monitoring of ground anchorages using artificial intelligence techniques." Thesis, University of Aberdeen, 2001. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=217212.
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Neural networks are a form of Artificial Intelligence based on the architecture of the human brain. They allow complicated non-linear relationships to be learnt from example data, and for further test data to be identified according to the relationship previously learnt. This allows the construction of control systems and diagnostic systems of geotechnical processes which were previously not possible due to their complicated non-linear nature. The main topic of research is the application of neural networks to the diagnosis of the condition of ground anchorages. Ground anchorages are in use in many engineering structures such as tunnels, retaining walls and dams and it has been reported that only 5-10% are routinely monitored during service. The conventional method of testing is load lift-off testing, which is expensive and time consuming. The patented technique, GRANIT, makes use of neural networks to learn the complicated relationship between the vibrational response of an anchorage to an applied axial impulse and its post-tension level. Research has been conducted into the parameters of the system which affect the diagnostic ability of the neural network. Further research into the application of the GRANIT technique to the identification of other faults in the anchorage has been conducted, such as change in free length, or gaps in the grouting. An automated procedure for the identification of the frequencies of interest in the response signatures of the GRANIT system has been investigated, and an example is given of an application of this automated procedure in the area of vibro-impact ground moling, a patented technique which uses both vibration and impact to maximise its penetration depth. Further research into the use of neural networks in an automated process has also been undertaken, and the development of a new technique is presented. This new technique has the potential of returning parameters of interest from any given group of signals, and has potential of application outwith geotechnical data. A patent application for this new technique has now been filed by the author.
4
Applegate, Steven M. "The design of column base anchorages for shear and tension." Master's thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-01202010-020157/.
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Hao, Jinde. "Dynamic responses of soil anchorages using numerical and centrifuge modelling techniques." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=24846.
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6
Riccardi, Francesco. "Experimental and numerical investigation of the interaction between concrete and FRP reinforcement anchorages." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST065.
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Des opérations de renforcement ou réparation sont souvent nécessaires pour garantir l’intégrité des structures en Béton Armé (BA) vis-à-vis du risque sismique. Dans ce cadre, le Polymère Renforcé de Fibres (PRF) stratifié au contact a démontré son efficacité pour améliorer le comportement en flexion des éléments de structures tant en termes de résistance que de ductilité. Afin d’en améliorer la liaison en proximité des jonctions, les ancrages noyés dans le béton représentent une solution avantageuse en termes de performances et de facilité de mise en place. Néanmoins, leur comportement mécanique est fréquemment associé à des mécanismes locaux de déformation qui peuvent affecter la réponse globale de la structure. Un nouveau montage expérimental a été donc conçu pour réaliser des essais de flexion in-situ sur des poutres renforcées de petite échelle avec l’utilisation de la tomographie 3D et étudier l’interaction entre le béton et les ancrages. L’objectif principal est de suivre grâce à la Corrélation d’Images Volumiques (CIV) l’évolution de la dégradation du matériau pendant le chargement et de reconstruire la cinématique de la zone renforcée. D’un point de vue numérique, un modèle éléments finis enrichis inspiré par la Méthode des Discontinuités Fortes (SDA) a été développé dans le but d’améliorer la représentation de l’interface. De cette façon, des comportements mécaniques complexes comme les phénomènes d’arrachement peuvent être facilement reproduits, en limitant en même temps le coût de calcul. La calibration du comportement d’interface est faite enfin grâce aux résultats des essais in-situ qui permettent de valider le modèle dans le cas de problèmes non-linéairesStrengthening and retrofitting techniques are often required for guaranteeing the integrity of Reinforced Concrete (RC) structures to prevent seismic risk. In such a framework, Externally Bonded (EB) FRP strengthening systems have proven their effectiveness in enhancing the flexural performances of structural members both in terms of bearing capacity and ductility. In order to improve the bond in the vicinity of RC joints, embedded anchors represent an attractive solution in terms of both performances and ease of installation. Nevertheless, their mechanical behaviour is often associated with localised deformation mechanisms that can strongly affect the overall structural response. A novel experimental apparatus has therefore been designed in order to carry out in-situ bending tests on small-scale strengthened beams in conjunction with 3D tomography and study the interaction between concrete and anchors. The main goal is to track the evolution of material degradation over the entire loading history by means of Digital Volume Correlation (DVC) and to reconstruct the kinematics of the strengthened region. From a numerical point of view, an enriched finite element model inspired by the Strong Discontinuity Approach (SDA) has been developed with the aim of improving the interface representation. By means of a kinematic enrichment, this strategy allows, on the one hand, to account for complex mechanical behaviours such as pull-out deformation modes and debonding mechanisms, on the other hand, to limit the computational effort. The calibration of the interfacial behaviour is then realised by means of the in-situ experimental results which allow to validate the model in the case of non-linear problems
7
Calcagno, Claire. "Aspects of seafaring and trade in the Central Mediterranean region, ca. B.C. 1200-800." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390282.
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8
Maziliguney, Levent. "Tensile Behavior Of Chemically Bonded Post-installed Anchors In Low Strength Reinforced Concretes." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608439/index.pdf.
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After the 1999 Kocaeli Earthquake, the use of chemically bonded post-installed
anchors has seen a great growth for retrofits in Turkey. Currently, chemically bonded
post-installed anchors are designed from related tables provided by adhesive
manufacturers and a set of equations based on laboratory pullout tests on normal or
high strength concretes. Unfortunately, concrete compressive strengths of existing
buildings, which need retrofit for earthquake resistance, ranges within 5 to 16 MPa.
The determination of tensile strength of chemically bonded anchors in low-strength
concretes is an obvious prerequisite for the design and reliability of retrofit projects.
Since chemically bonded anchors result in the failure of concrete, adhesive-concrete
interface or anchored material, the ultimate resistance of anchor can be predicted
through the sum of the contributions of concrete strength, properties of anchored
material (which is steel for this work), and anchorage depth. In this work, all three
factors and the predictions of current tables and equations related to anchorages are
examined throughout site tests.
9
Jebara, Khalil [Verfasser], and Joško [Akademischer Betreuer] Ožbolt. "Pryout capacity and bearing behavior of stocky headed stud anchorages / Khalil Jebara ; Betreuer: Joško Ožbolt." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1155761375/34.
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10
Holland, David Charles. "The behaviour of resin bonded rock bolts and other anchorages subjected to close proximity blasting." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU603184.
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The provision of a safe and economic rock support system is of primary importance for any excavation programme. If the excavation is to be developed by explosives, then the effect of blast forces on the performance of the rock support system must be considered. A review of current literature has highlighted a general lack of information regarding rock anchorage performance under blast loading. With this in mind, a full scale field test programme was undertaken to study the effect of close proximity blasting on resin bonded rock bolts, during the construction of the Pen y Clip Tunnel in North Wales together with a re-analysis of data from a previous study at the nearby Penmaenbach Tunnel. In both cases, accelerometers were used to monitor vibration and hydraulic load cells recorded the changes in rock bolt load during production face blasting. For the Pen y Clip trials, an additional monitoring system was developed which incorporated load cells positioned along the length of specially made experimental rock bolts. Further trials were conducted at an Edinburgh City Centre site to assess the likelihood of damage to temporary, cement grouted rock anchorages whose fixed anchors were positioned as close as 5m from nearby tunnel blasting. These trials involved the measurement of vibrations, both on the anchor head and down specially constructed boreholes, together with lift off load testing. Analysis consisted of the time and frequency domain examination of the signals, recorded on FM magnetic tape, from the three sets of field trials. Resin bonded rock bolts installed in microdiorite and rhyolite were found to be highly resilient to blasting, even those positioned down to lm from full face tunnel blasting. Temporary anchorages in mudstone were more susceptible to blasting but damage could be limited by monitoring of vibrations and careful control of blast parameters. The frequency response of the anchor head was found to be dependent on the characteristics of the anchorage and the nature of the environment in which it was installed. This raises the possibility that the analysis of spectral responses could form the basis of a technique for the non destructive testing of rock anchorages.
11
Hiew, Kee Hon. "Investigation of performance of carbon and glass fibre strengthened concrete beams with different end anchorages." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/1778.
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In this research, 12 reinforced concrete (RC) beams, comprising two beams as control beams, and 10 beams strengthened with fibre-reinforced polymer (FRP), were tested in a four-point bending configuration to determine the ability of externally bonded composite fabrics to improve the flexural capacity of a beam. The composite fabrics used were made of glass and carbon fibre. The fabrics were bonded to the RC beams using a two-part epoxy. These two fabrics were chosen to allow a variety of fabric strengths to be studied. The external bonded reinforcement (EBR) led to an average 240 per cent increase in flexural capacity. Different end anchorages and application configurations of the externally bonded glass and carbon fibres were evaluated to assess their effectiveness in minimising or preventing the debonding of these externally applied composite materials.The results indicate that the anchorages effectively prevented the debonding of the FRP laminates during flexural testing. Beams that were reinforced with glass fabric but without end anchorages failed, with tensile rupture of the FRP followed by debonding. Beams that were externally bonded with anchorages escaped debonding, instead suffering concrete crushing of the compression zone at mid-span as well as tensile rupture of the composite fabrics. However, the fibre reinforced composite concrete beams exhibited non-ductile failures, which suggests the need for further research to resolve these matters when designing the fibre post-strengthening system.
12
Puigvert, Cobos Francesc. "Analysis of circular bond-type anchorages for prestressing composite rods under quasi-static, fatigue and time-dependent loads." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/284216.
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En estructures pretesades sotmeses a ambients corrosius, s'està estudiant la possibilitat de substituir els tendons d’acer per tendons que no pateixin els efectes de la corrosió. En aquest sentit, els materials compostos Fibre Reinforced Polymer (FRP) són una opció duradora en el disseny d'estructures de formigó pretesat degut a les seves altes propietats mecàniques, pes lleuger i alta resistència a la corrosió. No obstant,
un dels reptes associats amb aquesta opció es troba en el desenvolupament d'un sistema d'ancoratge adequat
per als tendons de FRP .
Per això aquesta investigació ha estudiat la resposta mecànica d’ancoratges d’unió adhesiva per a tendons de FRP sota càrregues quasi-estàtiques, de fatiga i en funció del temps. Aquest objectiu s'ha aconseguit mitjançant la combinació d'una campanya experimental i un treball de modelatge amb el mètode dels elements finits.
En aquest sentit s’han dut a terme assaigs experimentals quasi-estàtics en els ancoratges d’unió adhesiva, observant que la ruptura del sistema es produïa en la unió adhesiva entre l’adhesiu i el tendó. En conseqüència, les principals variables estudiades van ser l’espessor de l'adhesiu i la longitud d’adhesió. A través d’una campanya de modelatge numèric amb diferents models, de complexitat creixent, del material adhesiu, es va investigar la resposta quasi-estàtica de l'ancoratge i el seu mecanisme de fallada. El model numèric va ser capaç de predir les dades enregistrades experimentalment quan el modelatge de l’adhesiu es va realitzar amb elements cohesius amb dany progressiu.
A més, s’ha desenvolupat una formulació analítica (i validat amb èxit) amb l'objectiu de proporcionar una distribució aproximada de les tensions de tall que es produeixen en la capa adhesiva per ancoratges amb adhesius que es comporten principalment elàstic lineal fins a ruptura. D’altra banda l'ancoratge d’unió adhesiva també es va investigar sota els fenòmens dependents del temps.
Per això es van dur a terme assaigs de fluència en unions simples Single Lap Joints ( SLJs ), per tal d'obtenir una llei experimental de fluència, i es van realitzar assaigs de relaxació de la tensió en els ancoratges per estudiar la pèrdua de càrrega en funció del temps. Durant aquests assaigs de relaxació es va estudiar la tècnica del retesat amb l’objectiu d’estudiar l’evolució de les pèrdues de tensió. Es va observar que la tècnica del retesat permet assolir càrregues de treball superiors amb una pèrdua de càrrega mínima.
A més a través d’un model visco-plàstic es va predir el temps de fallada a fluència de les SLJs i els ancoratges, basat en la llei de Bailey-Norton i calibrat amb les dades experimentals obtingudes en els assaigs de fluència de les SLJs. El dany de fluència es va modelar mitjançant la degradació de la tensió de fluència plàstica de l'adhesiu i el model numèric es va utilitzar per predir la pèrdua de càrrega dels ancoratges sota el fenomen de relaxació de la tensió. Els resultats enregistrats experimentalment van ser predits adequadament amb el model numèric proposat.
Finalment, es va investigar la resposta a la fatiga dels ancoratges d’unió adhesiva. Es van avaluar quatre configuracions d’ancoratge sota tres càrregues de fatiga d'amplitud constant. Els resultats experimentals van permetre l’obtenció d’una corba de vida a fatiga dels ancoratges en funció del nombre de cicles.
Mitjançant el mètode d’elements finits, també es va investigar el comportament a fatiga. La llei cohesiva obtinguda en l'anàlisi quasi-estàtic es va utilitzar en el model de la fatiga, on el dany per fatiga s’ha basat en la degradació de les propietats dels elements cohesius. El model numèric va predir amb èxit l'evolució dany per fatiga i la vida per fatiga observada experimentalment .
A partir del treball experimental i numèric realitzat en aquesta recerca, es proposen les recomanacions més pertinents per a un possible ús dels ancoratges d’unió adhesiva per tendons FRP en aplicacions de pretensat.In prestressed structures subjected to corrosive environments, consideration is being given to replacing the steels tendons with non-corrosive tendons. In this respect, Fibre Reinforced Polymer (FRP) materials are a durable option in the design of prestressed concrete structures for use in corrosive environments due to their high mechanical properties, light weight and high resistance to corrosion. However, one of the challenges associated with this option lies in developing a suitable anchorage system for FRP tendons. In the present work, the mechanical response of circular adhesively bonded anchorages for FRP tendons has been investigated under quasi-static, time-dependent and fatigue loading. This has been achieved through a combination of an experimental campaign and finite element modelling work. Experimental quasi-static tests of adhesively bonded anchorages were undertaken with failure occurring in the adhesive-tendon interface. The main variables assessed were the adhesive thickness and the bonded length. In order to investigate the quasi-static response of the bonded anchorage and its failure mechanism, a campaign of numerical modelling was carried out with different material models of increasing complexity for the adhesive layer. A cohesive zone model with progressive damage in the bonded joint was found to be in reasonable agreement with the experimentally recorded data. Additionally, an analytical formulation was developed (and validated against experimental data) with the aim to provide an approximate shear stress distribution in the bonded joint for circular anchors with adhesives which mainly behave linearly elastic up to failure. The adhesively bonded anchor for FRP tendons was also investigated under the time-dependent phenomena. Creep tests on Single Lap Joints (SLJs) were conducted in order to obtain an experimental creep law whereas stress relaxation tests were conducted on adhesively bonded anchorages to study the load loss in time. Furthermore, the restressing technique was assessed during the stress relaxation tests by restressing the specimens, to the original tensioning load, when the load loss was stabilised and constant. It was found that the restressing technique allows for the working load of the composite tendon to be reached with a minimum load loss. A visco-plastic material model, based on the Bailey-Norton law, was calibrated with the experimental data obtained from the creep tests and utilised to predict the creep time to failure of SLJs and anchorages. The creep damage was modelled by degrading the plastic yield stress of the adhesive. The viscoelastic model was also used to predict the load loss of the anchors under the stress relaxation phenomenon. The predicted load loss results were found to be in good agreement with the experimental results recorded. Finally, the fatigue response of the bonded anchorages was investigated. Anchorages with four different adhesive thicknesses were evaluated under three constant amplitude fatigue loadings. The experimental fatigue response of adhesively bonded anchorages was discussed and an experimental load-life average curve was obtained for all the anchorages. The fatigue behaviour was also predicted using Finite Element Analysis. A multi-linear traction-separation cohesive zone model was implemented at the adhesive-tendon interface. The cohesive law obtained in the quasi-static analysis was utilised in the fatigue model. The fatigue damage model utilised in this research was based on the degradation of the cohesive elements taking into account the fatigue damage evolution. The damage model was able to successfully predict the fatigue damage evolution and failure life experimentally observed. From the experimental and numerical work conducted in this investigation, the most relevant recommendations are proposed for a potential use of adhesively bonded anchorages for CFRP tendons in prestressing applications.
13
McAlpine, Patrick Charles. "Evaluation of the Effect of a Modified Wedge Geometry on the Behavior of Mono-Strand Post-Tensioning Anchorages." Thesis, Villanova University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10185436.
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The objective of this study is to create and evaluate if finite element modeling is a feasible approach to modeling different wedge geometries of post tensioned systems by comparing the experimental data from two wedges to analytical data. The motivation to develop an accurate finite element model of a wedge, tendon, and anchor system is to better understand the internal stresses the system is subjugated to and the interactions between components. By not fully understanding what is occurring within the anchor, the most efficient anchor cannot be designed. This can lead to premature failures of the strand which can result in total collapse of the structure. In recent years the applications of post tensioned strands have grown rapidly. Some of these applications require the strand to withstand higher strains than can currently be reached. An example of one of these applications is a shear rocking wall in earthquake prone areas. To date there is some experimental data on strand testing, but very little research has been conducted examining a modified geometry wedge. There is even less in depth literature on finite element modeling of the interactions between the components. One reason for this lack of research is because of the great variability in anchor and wedge configurations. Therefore, the focus of this research is to develop the interaction laws for one type of anchorage from one manufacturer. Once these laws are established and considered scientifically sound, the most efficient anchor wedge mechanism can be designed.
This thesis presents one of the stepping stone models needed to help converge on the interaction laws. The experimental component of this report evaluated two different wedge geometries. In the experimental trials the modified wedges preformed more efficiently than the standard wedges. The modified wedges were able to reach much higher strains. These geometries were modeled in a finite element program and the experimental results were replicated by adjusting the interaction relationships. The starting point for the relationships were based off of the studies found in the literature review. The results from analytical model of the standard wedges matched the experimental results very accurately. The analytical model of the modified wedge requires refinement. The results of the analytical model did not match the experimental observations as well as they should. However, the results still support the theory that the computer software can differentiate between standard and modified wedge geometries.
14
Schoening, Janna Caroline [Verfasser], Josef [Akademischer Betreuer] Hegger, Rolf [Akademischer Betreuer] Eligehausen, and John [Akademischer Betreuer] Cairns. "Anchorages and laps in reinforced concrete members under monotonic loading / Janna Caroline Schoening ; Josef Hegger, Rolf Eligehausen, John Cairns." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1195446640/34.
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Grosser, Philipp R. [Verfasser], and Rolf [Akademischer Betreuer] Eligehausen. "Load-bearing behavior and design of anchorages subjected to shear and torsion loading in uncracked concrete / Philipp R. Grosser. Betreuer: Rolf Eligehausen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2012. http://d-nb.info/1028801254/34.
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Osimani, Filippo. "The Use of Unbonded Tendons for Prestressed Concrete Bridges." Thesis, KTH, Bro- och stålbyggnad, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37000.
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Blue, Lucy Katherine. "A topographical analysis of the location of harbours and anchorages of the eastern Mediterranean in middle and late bronze ages, and their relation to routes of trade." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319120.
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Luis, Alberto Bedriñana Mera. "SEISMIC PERFORMANCE AND SEISMIC DESIGN OF DAMAGE-CONTROLLED PRESTRESSED CONCRETE BUILDING STRUCTURES." Kyoto University, 2018. http://hdl.handle.net/2433/235084.
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Curado, Marina Craveiro. "Ligações formadas pelo transpasse de armadura dobrada em forma de laço: análise da influência das fibras de aço." Universidade Federal de Goiás, 2011. http://repositorio.bc.ufg.br/tede/handle/tede/4331.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Curved anchorages shall be used once there is the need of reducing the necessary length for the transference of stresses between reinforcement and concrete. The transference of stresses in this case is performed not only through the bond between both materials but also through radial compression onto the concrete. Besides enhancing the bond properties between the reinforcement and the concrete, the addition of steel fibers to the concrete also enhances the strength to material tension contributing to avoid the splitting within the loop level. This paper aims at studying connections resistant to normal tension force composed by the overlapping of bent bars into loop shape. In order to do so, an experimental program was developed to evaluate the influence of some variables in the anchorage strength and connections formed by bent bars into loop shape. In both cases, the bending diameter of the loop and the grade of steel fibers added to the concrete were adopted as variables. Different development lengths regarding the pullout experimental data were also considered in order to assess anchorage strength. The influence over connection strength of the transversal reinforcement presence to the loop level was also analyzed. The outcomes of experimental data showed that the adopted bending diameter to the loop have influenced neither anchorage strength nor connections. Anchorage strength is related to the development length of the reinforcement within the concrete. Once 2% of steel fibers were added to the concrete, there was yielding of the reinforcement into a development length of only 50 mm. Regarding the connections, the presence of transversal reinforcement ensured a gradual loss of force within the post-peak section. Such reinforcement only influenced the connection strength when it was used together with 1% steel fibers. The fibers provided additions to the anchorage strengths and to the connections allowing the length reduction of anchorage loops. The strut and tie model was employed within the development of one expression to the calculation of the studied connection strength. Overall, the proposed equation tended to underestimate the values of maximum force.
As ancoragens curvas podem ser utilizadas quando se deseja reduzir o comprimento necessário para transferência de tensões entre as barras da armadura e o concreto. Neste caso, a transferência de tensões é realizada não apenas por meio da aderência entre os dois materiais, mas também por compressão radial no concreto. A adição de fibras de aço ao concreto além de melhorar as propriedades de aderência entre a armadura e o concreto, aumenta a resistência à tração do material, contribuindo para evitar o fendilhamento no plano do laço. Este trabalho tem como objetivo estudar uma ligação resistente à força normal de tração constituída pelo traspasse de barras dobradas em forma de laço. Para tanto, foi desenvolvido um programa experimental que buscou avaliar a influência de algumas variáveis sobre a resistência de ancoragem e de ligações formadas por barras dobradas em forma de laço. Nos dois casos, foram adotados como variáveis o diâmetro de dobramento do laço e o teor de fibras de aço adicionadas ao concreto. No caso dos ensaios de arrancamento, para avaliação da resistência da ancoragem, foram também considerados diferentes comprimentos de ancoragem. Investigou-se, ainda, a influência sobre a resistência da ligação da presença de armadura transversal ao plano do laço. Os resultados dos ensaios indicaram que o diâmetro de dobramento adotado para o laço não influenciou a resistência da ancoragem nem das ligações. A resistência de ancoragem está basicamente relacionada ao comprimento de embutimento da armadura no concreto. Com a adição de 2% de fibras de aço ao concreto houve o escoamento da armadura para um comprimento de ancoragem de apenas 50 mm. No caso das ligações, a presença da armadura transversal garantiu perda gradual da força no trecho pós-pico. Essa armadura influenciou a resistência da ligação apenas quando utilizada em conjunto com as fibras de aço no teor de 1%. As fibras proporcionaram acréscimos na resistência das ancoragens e das ligações, além de terem permitido a redução do comprimento de ancoragem dos laços. O Modelo de Bielas e Tirantes foi empregado no desenvolvimento de uma expressão para o cálculo da resistência da ligação estudada. De modo geral, a equação proposta tendeu a subestimar os valores de força máxima.
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Jambi, Safa Abdulsalam A. "Investigations into orthodontic anchorage." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/investigations-into-orthodontic-anchorage(b3769a47-e782-4b85-b8b4-21cb186e0fdd).html.
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Background and objectives: The control of anchorage is integral to successful orthodontic treatment. The objective of this research was to undertake three related projects to evaluate methods of increasing anchorage with the aim of adding to orthodontic knowledge and improve methods of treatment delivery. Methods: Two Cochrane systematic reviews were undertaken according to the methods published in the Cochrane Handbook for Systematic Reviews of Interventions, version 5.1.0. The influence of functional appliances on tooth position and the extraction decision was performed as a retrospective study using participants from a completed multicentre randomized trial. Results: 1- Statistically and clinically significant differences were found between the mean values of distal molar movement when surgical anchorage and conventional anchorage were compared. 2- Statistically significant differences were found between the mean values of distal molar movement and mesial upper incisor movement when intraoral distalising appliances and cervical headgear were compared.3- Fixed and removable functional appliances are equally effective in anchorage preparation. The type of functional appliance and time spent in Phase I treatment influenced the amount of lower incisor proclination. Conclusions: 1- Surgical anchorage is more effective than headgear without the inherent risks and compliance issues. However, intraoral appliances used in adolescence for distalisation of upper molars do not appear to have any advantages over cervical headgear. 2- Functional appliances reduce the anchorage requirements of a case primarily by reduction of the overjet, both fixed and removable functional appliances are equally effective in obtaining this. However, fixed functional appliances result in greater lower incisor proclination than removable functional appliances. 3- The type of functional appliance (removable or fixed) does not influence the extraction decision, however, this is influenced by overall space requirements.
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Theil, Ian. "Anchorage-dependent mammalian cell culture." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56768.
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Genetically engineered anchorage-dependent human embryonic kidney (293) cells were cultured at 37$ sp circ$C on 1 mm thick sheets of a fibrous polymeric matrix having an average fibre diameter of 10.2 $ mu$m and a void fraction of 0.81 using Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 2.5 mM glutamine. Immobilization efficiencies above 70% were observed when cells were added to 100 mL spinner flasks (operating at 60 rpm) containing 70 mL of medium and two 1 x 1 cm squares of matrix (total gross area of 2 cm$ sp2$) fastened to the base of the stirrer shaft. Loadings in excess of 2.4 $ times 10 sp7$ cells per cm$ sp2$ of matrix were measured after 2 h.The state of the cultures was followed by measuring the consumption of glucose and glutamine and the production of lactate and ammonium.
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Camli, Umit Serdar. "Anchorage Strength Of Fiber Reinforced Polymers." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606752/index.pdf.
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Fiber reinforced polymers (FRPs) have gained popularity in upgrade projects for reinforced concrete structural elements within the last decade because of its ease of application and high strength-to-weight ratio. In the design of an effective retrofitting solution by means of an FRP system, the anchorage capacity has an important role. This study presents the results of an experimental program conducted to determine the strength of carbon fiber reinforced polymers (CFRPs) bonded to concrete prisms or hollow clay tiles that are finished with or without plaster. In the experimental program, different types of anchorage methods were tested in a double shear push-out test setup. A simple and effective strength model is proposed for strip type anchorages based on the existing analytical models and experimental observations from this study. This new model is suitable for determining the design capacity of CFRP-to-concrete and CFRP-to- hollow clay tile joints with or without plaster and accounts for the presence of embedment and concrete strength. Obtained results by using this model were found to closely match with the experimental observations.
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Tsui, Wai-kin, and 徐偉堅. "Bone anchorage for orthodontic tooth movement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44661605.
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Littlejohn, G. S. "Studies relating to ground anchorage systems." Thesis, University of Edinburgh, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653958.
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This thesis comprises 28 papers which illustrate the nature and direction of development work and associated research undertaken between 1965 and 1993 on soil and rock anchorage systems. The research was performed in order to obtain a basic understanding of the behaviour of newly developed anchorage systems in a variety of ground types and conditions, in order to improve anchorage designs, construction methods and testing procedures, and thereby encourage the safe and economic application of ground anchorages worldwide. Field development of anchorage construction methods in gravels, sand, clays, marls and chalk using cement grout injection techniques is described together with equations evolved to estimate the ultimate resistance to withdrawal for each ground type, based on systematic testing of full scale anchorages. A new design method for single and multi tied stiff retaining walls installed in any soil is detailed and validated by large scale tests and closely monitored case histories. The interactions between wall, anchorage and soil are illustrated, coupled with the refinement of overall stability analyses in cohesionless soils using wedge and log spiral based mechanics of failure. For the rapid installation of anchorages in granular soils, vibratory driving is investigated in the laboratory and two distinct types of motion are found to exist. Theoretical equations of motion are developed to define the penetration processes and facilitate the design of vibrodrivers and vibrohammers. World practice in relation to the design, construction, testing and behaviour of rock anchorages is appraised, and field studies permit an improved understanding of uplift capacity by general shear failure, load transfer mechanisms, bond at rock/grout and grout/tendon interfaces, debonding, service performance and post-failure behaviour.
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Ivanović, Ana. "The dynamic response of ground anchorage systems." Thesis, University of Aberdeen, 2001. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165281.
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This thesis describes the development of the lumped parameter model and the results obtained from it. In order to fully utilise the response signatures obtained from GRANIT, it is essential to understand the effect of the various components of the 'complete ground anchorage system' such as protruding free and fixed length of the anchorage, anchorage head assembly, affected and non-affected rock mass. In order to monitor each subsystem and its dynamic response to potential changes/failures, the anchorage system, in its simplest form, is represented by the model which comprises seven masses and a number of spring/damper systems replicating the components described earlier. Ordinary differential equations for mass/spring/dash-pot elements were then configured and the model was implemented in software form and then solved for both time and frequency domain. The acceleration response was examined at a number of points in the anchorage system i.e. at the protruding length as well as at the anchorage head, along the free length, along the fixed length and even within the rock mass itself. Several laboratory and field anchorage applications were simulated using the lumped parameter model and the results obtained from the model. A parametric study was then undertaken with regard to addressing mechanisms which are generally present in anchorage applications such as changes of material properties of the resin and concrete, the introduction of defects, such as gaps along the fixed anchorage length or debonding at the proximal fixed anchorage length, and the influence of changes in post tension load on the dynamic response of the anchorages. Furthermore, an investigation of the impulse load was conducted with the aim of further development of the current impact device in order to be able to assess anchorages regarding the mechanisms mentioned earlier.
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Ibell, Timothy. "Behaviour of anchorage zones for prestressed concrete." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259477.
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Muhamad, Khairussaleh Nor A. "Fatigue of cable anchorage on cable stayed bridge." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/811083/.
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Studies have shown that the connection details used for cable anchorage blocks on cable-stayed bridges have the potential for fatigue damage due to fluctuating stresses generated by the cyclic traffic loads passing over the bridge. To investigate the fatigue damage and determine the remaining fatigue life of a cable anchorage block used on a cable-stayed bridge, finite element (FE) analyses were undertaken by using the Fatigue Load Model 4 (FLM 4) proposed by the Eurocodes to identify the most fatigue-critical locations within the details. One of the main objectives of this research was to identify the critical area prone to fatigue in the anchorage block due to the response in traffic loads. Therefore, two types of numerical models of a typical cable anchorage block were analysed as a three dimensional sub-model which was driven by global cable forces obtained from the global analysis of a three-span cable-stayed bridge. These models are of the cable anchorage block without the longitudinal girder modelled and the cable anchorage block with the longitudinal girder modelled. The cable anchorage blocks without the longitudinal girder model were classified into three categories of model types namely; model types 0, A and B. Similarly, the cable anchorage blocks with the longitudinal girder model were classified as model types A-G, B-G and C-G. These model classifications are based on several boundary conditions simulated in the analyses. In addition to this, the fatigue behaviour of the cable anchorage block was analysed by using three different approaches namely; by using the nodal stresses at the location of the stress concentration (node stress concentration), by using a stress averaged over an area in the vicinity of the stress concentration (average elements) and by using the hot-spot method, in order to identify the stress ranges that adversely affect the remaining fatigue life of cable anchorages. Each approach was analysed with three different mesh sizes; 5mm by 5mm, 10mm by 10mm and 20mm by 20mm in order to carry out a mesh sensitivity analysis of the resulting stresses and associated stress ranges. The 10mm by 10mm mesh size was found to be most appropriate for this fatigue appraisal. This finding is supported because the 10mm by 10mm mesh size is specified in several code of practices such as the International Institute of Welding (IIW) and BS 7608 as guidance for use when determining hot-spot stress when using the hot-spot method for the fatigue analyses of a welded detail. The critical stresses from model type C-G were used in the fatigue appraisal as the behaviour of this model represented more accurately the actual cable anchorage block on the cable-stayed bridge compared to the other types of models used. Model type C-G were selected for further fatigue appraisal as this model include the correct boundary conditions and applied load that represented the actual condition of the anchorage behaviour on the cable-stayed bridge. This included the movement of the top anchorage block due to the displacement of the cable and in addition the deck movement. Also, non-uniform pressure was applied on the bearing plate which was included to model possible construction tolerances which was one of the important properties of the model type C-G. In evaluating the possible fatigue damage in the cable anchorage block, the cumulative model for fatigue failure expressed in terms of Miner’s rule was used. In addition to this, the condition of the structural detail due to fatigue with increasing traffic loading was determined by projecting traffic volume increases of up to 20%. Based on the results calculated, if the long distance traffic characteristic was used in fatigue appraisal, the cable anchorage block was justified to be not ‘safe’ as the damage accumulation for fatigue, Dd at the top gusset was recorded as 1.270, which exceeded the limiting value of 1.0 corresponding to a 120 year design life. However, if medium distance traffic characteristic was used in the fatigue appraisal, the cable anchorage block will remain ‘safe’ except when a 20% increase in traffic volume was included in the analysis, which resulted in Dd value of 1.016. Also, if a more conservative value of Dd = 0.5 as suggested by IIW (2008) was used, the cable anchorage block appraised by using both the long distance and medium distance traffics was found not safe from fatigue damage and would not survive its design working life without structural repair. For future fatigue appraisals of anchorage blocks (and other important structural details), it is strongly recommended that the numerical model of anchorage block is analysed together with the longitudinal girder using the hot-spot method. A 10mm by 10mm finite element mesh size is suggested and it is also necessary to specify the displacement at the top of the anchorage block to simulate the cable movement together with the girder movement both of which are obtained from the global analysis of the whole bridge structure.
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Hui, Macarious Kin Fung. "Anchorage of stirrups in prestressed concrete I-girders." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57783.
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The current research investigates the performance of commonly-used non-code-compliant stirrup detailing in concrete I-girder bridges, specifically when the lower hooks on the stirrups are oriented parallel to the longitudinal prestressing strands and are not bent around any longitudinal bars. Such detailing does not meet the specifications in the Canadian Highway Bridge Design Code CSA S6-06. An experimental investigation was conducted on full-scale partial sections of a concrete I-girder to evaluate the performance of such non-code-compliant stirrup anchorages by comparing their performance to the performance of code-compliant stirrup anchorages. An analysis of an example concrete I-girder bridge was conducted to determine the demands on the stirrup anchorage during the tests. In the tests, the flexural tension force was applied to the prestressing strand while a diagonal force was applied to the web of the test specimens at approximately 30° to the longitudinal axis of the specimen. Two pairs of stirrups were fixed to a support as the diagonal force was applied. The ratio of the slip of the stirrup to the strain along the exposed length of the stirrup, which equals to the debonded length, was monitored in order to observe the performance of the stirrup anchorage. After applying many cycles of the diagonal force, including about 100 cycles after yielding of the stirrups, the non-code-compliant hooks were found to perform adequately.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Boizard, Sophie Marie Dominique Sandrine Valerie. "The ecology and anchorage mechanics of kelp holdfasts." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31258.
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The intertidal zone on wave-swept shores is among the most stressful environments on earth. The ability of organisms to survive and thrive in such environments depends on their ability to withstand breakage and wave dislodgement. The research presented in this thesis investigated two aspects of the biology of kelp holdfasts. I first examined whether the recruitment of the kelp Hedophyllum sessile was facilitated by the presence of holdfasts of adult conspecifics and how canopy cover and wave-exposure mediated this interaction. Field experiments indicated that adult holdfasts and substrata of high structural complexity, such as articulated coralline algae, enhanced recruitment. However, the ability of structurally complex substrata to facilitate recruitment depends largely on the extent of canopy cover and to a lesser extent on wave-exposure. Mechanisms by which canopy cover mediates substratum-specific recruitment processes may hold significant implications for population persistence and successful recruitment, especially following periods of high disturbance. Secondly, I investigated the functional morphology of the holdfast of the kelp Laminaria setchellii in relation to its role in providing attachment to the substratum and resistance against wave dislodgment. Results of field investigations indicated that the thallus of L. setchellii responds to increased wave exposure by decreasing blade size and increasing holdfast size; a concomitant increase in holdfast attachment force was not observed. At high wave exposure sites, the integrity and attachment of L. setchellii holdfasts is jeopardized by the presence of barnacles and burrowing crabs. Field investigations further showed that L. setchellii exhibits asymmetry with respect to the prevailing wave direction. The blade and upper part of the stipe are oriented with their longer axis perpendicular to the flow so that reconfiguration and bending is facilitated. The lower part of the stipe and holdfast are oriented with their longer axis parallel to the flow, resisting bending. By exhibiting such pattern of asymmetry along it thallus, L. setchellii avoid large hydrodynamic forces while still avoiding large swaying and remaining off the substratum in water of higher light intensities and velocities.Science, Faculty of
Botany, Department of
Graduate
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Gad, Annica. "Cell cycle control by components of cell anchorage /." Stockholm : Division of Pathology, Karolinska institutet, 2005. http://diss.kib.ki.se/2005/91-7140-359-0/.
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French, David Joseph. "Investigations of a novel pile and anchorage concept." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46305.
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Cremona, C. A. "The role of anchorage in cell cycle control." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/16663/.
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Mammalian cells generally require both mitogens and anchorage signals in order to proliferate. Failure to receive these signals results in either cell-cycle arrest or cell death, known as anoikis, due to activation of anchorage-dependent checkpoint mechanisms. Transformed cells alleviate these checkpoints, via activation of oncogenes and/or inactivation of tumour suppressors. In contrast, detachment of normal cells halts cell-cycle progression in G1, because of insufficient cyclin D1 induction to overcome the Rb/E2F checkpoint, accumulation of cyclin-dependent kinase inhibitors, and lack of cyclin A production. Because of the complexity of anchorage-dependent mechanisms involved, several changes are required for cells to become anchorage independent: impairment of both Rb and p53 pathways, plus activation of Ras. These specific defects are found in many human cancers, and anchorage independence correlates strongly with tumourigenic potential. Here I have used cells expressing SV40 LT, with and without oncogenic Ras, to model the changes leading to anchorage independent proliferation. Importantly, cells expressing SV40 LT alone retain their anchorage dependence, despite Rb and p53 inactivation. However, the mechanism responsible for this cell-cycle arrest in suspension is not known. Using immunoprecipitation and kinase assays, I demonstrated that the cyclin-dependent kinase inhibitor p27 curbs cell-cycle progression in these cells. FACS analysis showed that surprisingly, these cells do not undergo a robust checkpoint arrest, but instead stall throughout the cell cycle, showing abnormal DNA replication. Further investigation by metaphase spread showed the accumulation of aneuploid nuclei, indicating the development of genomic instability. This resulted in a higher rate of transformation among cells cultured without anchorage for a limited time. This work demonstrates that anchorage signals enable proper activation as well as assembly of cyclin-dependent kinase complexes, and that adhesion is particularly important for maintaining orderly cell-cycle progression and preventing genomic instability in checkpoint-deficient cells.
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Amin, Rizgar. "End anchorage at simple supports in reinforced concrete." Thesis, London South Bank University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685978.
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Chen, Qing-Li. "Effect of surface topography on hip prosthesis anchorage." Thesis, Queensland University of Technology, 1997.
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Ngan, Caroline Lai Yung. "Experimental investigations of anchorage capacity of precast concrete bridge barrier for Performance Level 2." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1518.
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In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code.
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Sandler, Jonathan. "A comparison of the effectiveness of three methods of anchorage reinforcement in the treatment of maximum anchorage patients : a randomised clinical trial." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5262/.
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The primary intention of this study was to add to the body of scientific evidence by determining whether a recently introduced method of anchorage reinforcement, namely Temporary Anchorage Devices (TADs), is effective. It is clear that there are several commonly used methods for anchorage support but some of these are totally dependent for success upon good patient compliance. Orthodontic clinicians would enthusiastically welcome as an alternative, an effective and efficient method that is less dependent upon patient co-operation. The introduction of new orthodontic techniques is rarely supported by high quality evidence on efficiency or effectiveness, in advance of them being promoted for widespread clinical use. New appliances and techniques are often promoted based upon very low levels of clinical evidence. Temporary Anchorage Devices were first introduced in 1983. Since then many papers have referred to Temporary Anchorage Devices as a source of stationary anchorage yet to date, few Randomised Clinical Trials (RCTs) have been carried out into this treatment method. AIMS To evaluate the effectiveness of Temporary Anchorage Devices for orthodontic anchorage when compared with the Nance button palatal arch and to Headgear. METHOD The TADs assessment trial is a prospective, dual-centre RCT involving 78 ‘maximum anchorage’ patients between 12 and 18 years of age with 39 males and 39 females. The three treatment arms of the study were Headgear, a Nance button palatal arch and TADs. Outcomes recorded included: anchorage loss measured both on lateral cephalometric radiographs and 3D model scanning, length of treatment, number of visits, quality of the outcome and the patients’ perception of the various treatment methods. RESULTS Sample summary showed the groups to be matched in terms of age, start PAR score and SNA. There was a statistically significant (p=0.002) overall effect of treatment when the right molar position was assessed on cephalograms. The Nance group lost 2.03mm (0.81-3.25) more anchorage than the Headgear group. No other statistically and clinically significant results were recorded between the groups on the cephalograms or on the superimposed digital models. Mean treatment times in months varied from 26.83 (SD 9.35) to 28.01(SD 5.38) and the total number of visits from 18.38 (SD 5.95) to 21.77 (SD 4.41). Casual visits and DNAs were almost identical between the groups but PAR scores were nearly 4 points better with TADs than Headgear and Nance. This result was statistically and clinically significant. From the patient questionnaires, the comfort levels both on placement and removal were similar with TADs and the Nance, and both techniques were highly recommended by the patients. Headgear was more troublesome and much less popular with the patients. CONCLUSIONS 1) There is no difference in the effectiveness of temporary anchorage devices, Nance button palatal arches and headgear in reinforcing anchorage in orthodontic treatment. 2) Patients’ perceptions suggest that there were greater problems with headgear and Nance buttons, than with temporary anchorage devices. 3) The quality of treatment as measured by PAR scores was significantly better with TADs than with headgear 4) Temporary anchorage devices may be the preferred method of choice for reinforcing orthodontic anchorage.
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Weckert, Steven Mining Engineering Faculty of Engineering UNSW. "Anchorage and encapsulation failure mechanisms of rockbolts ??? stage 2." Awarded by:University of New South Wales. School of Mining Engineering, 2003. http://handle.unsw.edu.au/1959.4/19219.
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The Fully Encapsulated Resin Bolt (FERB) is widely utilised for strata control and ground support in civil and mining applications worldwide, with approximately 6 million installed per annum by the Australian coal mining industry. Independent studies have concluded that 30-35% of these rockbolts, which represents an annual expenditure of $40 million, are ineffective. The anchorage and failure mechanisms of FERB are yet to be quantified, and support systems are designed primarily from empirical rather than scientific methods. There are no standardised methods of assessing FERB components, installation techniques and support behaviour. The majority of research into FERB support systems remains commercial intellectual property, with little information released into the public domain. This thesis investigated several variables of FERB support systems, and also examined differences between field and laboratory pull-out test load distributions. This research was conducted in two phases, with Phase 1 seeking standardised methodology and repeatability in results, while Phase 2 further refined Phase 1 methods and extended the range of tests. The results in both phases were encouraging, with reasonable repeatability attained in all testing series. The findings included: ??? Annulus Thickness: There was little change in load capacity with small annulus thickness, however the maximum peak load (MPL) significantly reduced once annulus thickness exceeded 4mm ??? Resin Installation Spin Time: Underspinning of cartridge resin was found to have an insignificant effect on rockbolt load/deformation characteristics. Overspinning, however, led to a dramatic reduction in anchorage performance with a lessening in both MPL and stiffness ??? Rockbolt Load Transfer: The magnitude of an applied load reduced to zero along the length of the rockbolt, being greatest nearest the rock free surface (the point of load application). An exponential reduction was found when tested in the manner of laboratory tests, with the loading jack reacting against the free surface. This reduction was linear when the load was applied as in the field, with no load placed on the free surface This basic investigation into FERB support systems has validated many empirical understandings of rockbolts, while highlighting the need for further testing into several key areas.
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Ahmad, BouSaleh. "Effects of anchorage details on response of deep beams." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98946.
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As part of a research program at McGill University, involving the testing of eight full-scale deep beams, this research studies the response of four full-scale deep beams that were designed in accordance with the strut-and-tie model provisions of the CSA Standard A23.3 (2004). All of the deep beams had a centre-to-centre spacing of 2000 mm between the two supports, 1000 mm in height, and 350 mm in thickness. They were simply supported with an application of a single point load at midspan. The total length of the four beams varies depending on the type of anchorage being used. The four anchorage details that were considered in this study include a straight development length, a standard 90 degree hook, friction-welded 1.5 in. (38 mm) diameter circular headed bars and friction-welded 2 in. (50 mm) diameter headed bars. The dimensions of the loading pad and the bearing pads were 200 mm (and 300 mm) and 100 mm, respectively. All beams were reinforced with two layers of five 15M bars forming the tension tie reinforcement. El-Jorf (2006) carried out the testing and analysis of the other four full-scale deep beams in this overall research program.This research project demonstrated that providing friction-welded circular headed bars capable of developing the full yield strength at the head results in shorter beams and improved response compared to straight bar embedment details. Providing a lead-in length as well as friction-welded circular headed bars, with reduced head size, provides improved ductility compared to the straight bar embedment and compared to the hooked anchorage. This research also shows that benefits of confinement pressures at the supports can increase the bar stress although the provided development length is below code requirements.
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Baldwin, Marc Lllya. "The assessment of inadequate anchorage in reinforced concrete structures." Thesis, University of Birmingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490768.
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Bennitz, Anders. "Mechanical anchorage of prestressed CFRP tendons : theory and tests /." Luleå : Division of Structural engineering, Department of Civil, Mining and Environmental Engineering, Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1757/2008/32/.
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Dua, Rupak. "Enhanced Anchorage of Tissue-Engineered Cartilage Using an Osteoinductive Approach." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/context/etd/article/2559/type/native/viewcontent.
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Articular cartilage injuries occur frequently in the knee joint. Several methods have been implemented clinically, to treat osteochondral defects but none have been able to produce a long term, durable solution. Photopolymerizable cartilage tissue engineering approaches appear promising; however, fundamentally, forming a stable interface between the tissue engineered cartilage and native tissue, mainly subchondral bone and native cartilage, remains a major challenge. The overall objective of this research is to find a solution for the current problem of dislodgment of tissue engineered cartilage at the defect site for the treatment of degraded cartilage that has been caused due to knee injuries or because of mild to moderate level of osteoarthritis. For this, an in-vitro model was created to analyze the integration of tissue engineered cartilage with the bone, healthy and diseased cartilage over time. We investigated the utility of hydroxyapatite (HA) nanoparticles to promote controlled bone-growth across the bone-cartilage interface in an in vitro engineered tissue model system using bone marrow derived stem cells. We also investigated the application of HA nanoparticles to promote enhance integration between tissue engineered cartilage and native cartilage both in healthy and diseased states. Samples incorporated with HA demonstrated significantly higher interfacial shear strength (at the junction between engineered cartilage and engineered bone and also with diseased cartilage) compared to the constructs without HA (p < 0.05), after 28 days of culture. These findings indicate that the incorporation of HA nanoparticles permits more stable anchorage of the injectable hydrogel-based engineered cartilage construct via augmented integration between bone and cartilage.
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Gale, Luke. "Behaviour of multiple anchorage systems for FRP-prestressed concrete structures." Thesis, University of Bath, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425631.
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McDermott, Ruth Helen. "The adaptation of anchorage-dependent cells to glutamine-free medium." Thesis, Manchester Metropolitan University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294056.
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Cavalancia, James. "EFFECTS OF A LINGUAL ARCH AS MAXIMUM ANCHORAGE IN ORTHODONTICS." Master's thesis, Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/456182.
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Oral BiologyM.S.
Lingual arches are frequently used in orthodontic extraction treatment, with the intended purpose of achieving maximum anchorage in the mandibular arch; however, little evidence exists in the literature that supports this anchorage approach. The lingual arch is widely supported in the literature for space maintenance and sagittal correction. It has been proven effective at minimizing any decreases in arch depth and perimeter when there is early loss of primary teeth. Theoretically, the lingual arch as a passive maintenance appliance should exert no forces on the teeth, yet studies have shown both the molars and incisors to move. To examine its anchorage efficiency further, we compared incisor and molar position in extraction treatment with and without the use of a lingual arch. Pre and post-treatment cephalograms that included lower premolar extractions were recruited from a depository of images. Canine retraction with power chain or NiTi closing coils with or without the use of a lingual arch for maximum anchorage were compared for incisor and molar position. Angular and millimetric measurements for IMPA, L1-NB, L1-APog and molar mesialization were measured and compared using a t-test. The greatest difference between pre and post-treatment was the IMPA with 5.19° more uprighting of the incisors in the group with no lingual arch, followed by 4.38° more uprighting in the L1-APog measurement. However, none of the differences between the groups were significant: IMPA (p=0.129), L1-NB (angular p=0.161, millimetric p=0.205), L1-APog (angular p=0.197, millimetric p=0.196) and mesialization of the molar (p=0.308). The change in incisor and molar position does not significantly differ with or without the use of a lingual arch in extraction treatment. Clinically, this suggests that the lingual arch does not provide maximum anchorage. Another modality, such as TADs, may provide a better source of anchorage for space closure.
Temple University--Theses
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Selkregg, Sheila Ann. "The Decision and Rationale which Led to Construction on High-risk Land after the 1964 Alaska Earthquake: Analysis of Risk-based Cultural Dissociation." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/1302.
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Many lives and much property are lost in disasters when individuals and communities choose to ignore information which could mitigate the potential disaster. This case study examines community and individual decision processes and rationale which led to construction of a high-occupancy high-rise courthouse on land designated as high risk after the 1964 Alaska earthquake. The study reviews policy and decision making, psychology, and risk management literature to explore the psychological mechanisms and processes of hazard mitigation decisions.
It questions why individuals and communities choose not to mitigate when they have the information which makes risk mitigation possible. The hypothesis theorizes risk-based cultural dissociation and submits that individuals and society process risk-related information in a manner that allows for interpretation and acknowledgement of information so that it is compatible with individual and social agendas and constructs. Society and individuals can and do completely deny or dissociate from risk-related information.
This exploratory research uses macro, meso, and micro levels of analysis to examine the environmental setting, land ownership and power, and professional and public seismic information. This examination is placed in the context of Anchorage's post-earthquake reconstruction momentum.
Indepth interviews with elected officials, a bank president, insurance executives, investors, builders, appointed officials, private and public professionals, court representatives, a judge, a juror, and citizens provide insight into risk perception and individual and community agendas. The interviews revealed each level of analysis had different perceptions of risk and different agendas.
Professional warnings not to reconstruct on high-risk land were ignored. Downtown economic interests and powerful individuals significantly impacted the community decision process. One charismatic leader played a major role in the community reconstruction and courthouse decisions.
Research findings support the hypothesis. Individuals consistently chose to deny earthquake potential in their daily lives. Selective interpretation of information allowed individuals to support their own agendas. Community decision processes allowed deletion of important information and a transference of responsibility, resulting in no decision body or individual feeling responsible for the decision. Risk-based cultural dissociation is defined and presented in this research as a direction for future study.
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Garrett, Scott J. "Implementation of Canon 1112 [section] 1 to the Archdiocese of Anchorage." Theological Research Exchange Network (TREN), 2006. http://www.tren.com/search.cfm?p029-0679.
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Schreiber, Alex C. "Success rates of temporary anchorage devices placed in an orthodontic clinic." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/schreiber.pdf.
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Indridason, Birgir. "Earthquake Induced Behavior of Submerged Floating Tunnels with Tension Leg Anchorage." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23538.
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SUMMARY:The purpose of this study is to examine the behavior of a submerged floating tunnel (SFT) anchored by tension legs and subjected to seismic excitation. A proposal of a tunnel crossing the Høgsfjord in Norway is used as a case for the finite element model. The tunnel was proposed as 1345m long with a cross section diameter of 11.3 m. Furthermore, the tunnel should lie 25m under the sea surface to enable regular sea traffic. A seismic analysis of the SFT is performed using a pseudo-excitation method (PEM), which is based within the framework of random vibration methods. The coherency between different supports is studied, in particular the incoherence and wave passage effects. A simple constant incoherence model is introduced, for coherency between inter-components of motion. Three cases of the incoherence are then examined: (i) fully coherent, (ii) incoherent and, (iii) non-coherent. The seismic analysis is carried out for different velocities and angles of the propagating earthquake waves. The structure is modeled in Abaqus, by using beam elements for both the tunnel and the tension legs. The fluid/structure interaction is modeled and its effects on the structure are discussed. The SFT is modeled with both vertical and inclined tension legs and the behavior of the models are investigated, with regard to seismic events. The seismic analysis is performed in Matlab, by developing m-scripts based on the system matrices generated in Abaqus. The results from the analysis confirm the importance of accounting for the stochastic nature of seismic waves. Furthermore, the results suggest that submerged floating tunnels with tension leg anchoring are reliable when subjected to earthquake excitation. It is unlikely that earthquake action will be taken as the design load case for Norwegian conditions.
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Shave, Jonathan David. "Shear assessment of concrete bridges : anchorage effects and use of plasticity." Thesis, University of Bath, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415398.
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Muhaj, Helisa. "Seismic strengthening of reinforced concrete beams by post-tensioning with anchorages by bonding." Doctoral thesis, 2020. http://hdl.handle.net/10362/103102.
Full textAbstract:
RC moment resisting frame buildings are one of the most used structural systems in seismic
prone regions. These structures dissipate energy by concentrating the inelastic behaviour (i.e. the damage)
in the plastic hinge regions of the structural elements, that form preferably on the beams ends.
Since Capacity Design has been part of the Design Codes for some years now, some moment resisting
frame buildings have suffered seismic events. Although in most of the cases the ductile performance
of structures has successfully preserved the human lives and no collapse has occurred, deficiencies
regarding the residual capacity and high level of post-earthquake damages have surfaced. The importance
of other solutions that offer higher cost-efficiency and are more resilient has emerged.
Some studies have shown that damage limitation leads to high seismic performance of structural
systems even. This technology was developed at first for application in precast industry, PRESSS
program. Considering the vast amount of existing structures built following the Capacity Design and
the advantages of Damage Avoidance Design, strengthening by post-tensioning with adhesive anchorages
is proposed in this dissertation as a promising intervention for improving the seismic behaviour
of ductile beams. This solution takes advantage of self-centering capacity of unbonded PT strands,
whereas development of bonded anchorages turns this solution suitable for application in residential
/ business frame buildings. The results obtained from four RC beams tested experimentally will be
presented herein, including one reference and three strengthened specimens. The strengthened beams
had reduced residual deformation and enhanced load capacity. The behaviour of the beams tested
experimentally was also studied through numerical analysis. The attained results show that strengthening
by post-tensioning with bonded anchorages represents a suitable intervention for reducing the
impact of seismic events. Reduced damage of structural elements in RC frame after a seismic event
leads to reduced (or absence) cost of repair and building downtime.