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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
761

Plan Modifications Within The Contexts Of Planning Control Mechanisms, Mersin Case

Unlu, Tolga 01 December 2005 (has links) (PDF)
Urban development plans in the Turkish planning system envision that a time would come and the spatial development of any city would be completed in the specific planning period. The allegation of the planning system is to control every detail during urban development. However, the static nature of development plans within the regulatory context cannot provide strategies to manage the dynamic nature of the socio-political context. This contradictory situation involves tensions in planning control mechanisms and creates cleavages within the spatial context. &amp / #8216 / Changes in the spatial context&amp / #8217 / are the indicators of such cleavages. They are conceived to be significant since they might enhance or erode the distinctiveness of a place. To the extent that possibility of change is disregarded in static nature of urban development plans, plan modifications become the primary tools for emergence of the &amp / #8216 / changes in spatial context&amp / #8217 / . They usually emerge through individual actions and individuals begin to produce their own pattern of urbanism in the urban built environment. Management and control of &amp / #8216 / changes in the spatial context&amp / #8217 / is at the very center of the study. It is about shaping the physical form of development rights. The study aims to evaluate the qualitative and quantitative influence of plan modifications on the spatial context through a study within the whole contexts of planning control mechanisms. Hence, the study also concentrates on the operation of planning control mechanisms in the Turkish planning system. The plan modifications are evaluated throughout a detailed analysis held within boundaries of Municipality of Greater Mersin.
762

Experimental Analysis of Water Based Drilling Fluid Aging Processes at High Temperature and High Pressure Conditions

Zigmond, Brandon 2012 August 1900 (has links)
In efforts to render the safest, fastest, and most cost efficient drilling program for a high temperature and high pressure (HT/HP) well the maximization of drilling operational efficiencies is key. Designing an adequate, HT/HP well specific, drilling fluid is of most importance and a technological challenge that can greatly affect the outcome of the overall operational efficiency. It is necessary to have a sound fundamental understanding of the behavior that water-based muds (WBM) exhibit when exposed to HT/HP conditions. Therefore, in order to adequately design and treat a WBM for a HT/HP well specific drilling program, it is essential that the mud be evaluated at HT/HP conditions. Currently, industry standard techniques used to evaluate WBM characteristics involve aging the fluid sample to a predetermined temperature, based on the anticipated bottom hole temperature (BHT), either statically or dynamically, for a predetermined length, then cooling and mixing the fluid and measuring its rheological properties at a significantly lower temperature. This, along with the fact that the fluid is not subjected to the anticipated bottom hole pressure (BHP) during or after the aging process, brings to question if the properties recorded are those that are truly experienced down-hole. Furthermore, these testing methods do not allow the user to effectively monitor the changes during the aging process. The research in this thesis is focused on evaluating a high performance WBM and the current test procedures used to evaluate their validity. Experimental static and dynamic aging tests were developed for comparative analysis as well to offer a more accurate and precise method to evaluate the effects experienced by WBM when subjected to HT/HP conditions. The experimental tests developed enable the user to monitor and evaluate, in real-time, the rheological changes that occur during the aging of a WBM while being subjected to true BHT and BHP. Detailed standard and experimental aging tests were conducted and suggest that the standard industry tests offer false rheological results with respect to true BHT and BHP. Furthermore, the experimental aging tests show that high pressure has a significant effect on the rheological properties of the WBM at elevated temperatures.
763

Reducing remodularization complexity through modular-objective decoupling

Chern, Rick 11 1900 (has links)
This dissertation defines "modular-objective coupling", and shows that programming language designs which imply reduced modular-objective coupling reduce complexity of remodularizations--behaviour-preserving restructurings for which the only intended goals are to change program source code structure. We explicitly distinguish between two points of view on program structure: modular structure--the structure of a program as a set of static text documents, and objective structure--the structure of a program as a dynamic computational model during execution. We define modular-objective coupling as the degree to which changes in modular structure imply changes to objective structure, for a given programming language. We use the term remodularization to refer to any behaviour-preserving source code restructuring, for which the only intended goal is to change modular structure. We argue that programming languages with strong modular-objective coupling introduce accidental complexity into remodularizations, by requiring complex objective structure changes to achieve intended modular structure changes. Our claim is that a programming language design which implies reduced modular-objective coupling reduces remodularization complexity in the language. To validate this claim, we first present SubjectJ, a subject-oriented programming system that extends Java. The design of Java implies strong modular-objective coupling, while SubjectJ is designed for reduced modular-objective coupling. We then perform a series of remodularization case studies comparing Java and SubjectJ. Our results suggest that remodularizations are less complex in SubjectJ.
764

The reliability and validity of surface electromyography to study the functional status of the lumbar paraspinal muscles

Kamei, Ken, ken.kamei@student.rmit.edu.au January 2010 (has links)
The aim of this thesis is to determine whether surface electromyography (EMG) can be used as a diagnostic tool in chiropractic practice to identify the functional status of the lumbar paraspinal muscles. There were two main studies to achieve this aim. The reliability and validity of the surface EMG signal to measure the activity of paraspinal muscles during maintenance of simple static postures was evaluated. During maintenance of static postures, the raw surface EMG signal was often contaminated by an electrocardiographic (ECG) signal. Although the ECG artefact was successfully removed using two different ECG removal techniques (manual and semi-automatic), the reliability of the surface EMG signal was not significantly improved (ICC less than 0.75) for both non-normalised and normalised data. Therefore the static postures that were used in this thesis did not provide a protocol that can be used to measure the functional status of the lumbar paraspinal muscles in clinical practice. However, when muscle contraction was at a moderate level, the reliability of EMG signal became better. Walking was considered to be a possible protocol to record a reliable surface EMG signal from paraspinal muscles. Three components of the surface EMG signal were used to characterise the pattern of muscle activity during steady state walking. The narrow window technique was used to characterise the peak activation point of the activity envelope in order to capture a stationary signal from which to calculate amplitude and frequency measures. Walking is a cyclic activity. The back muscles contract rhythmically during a single gait cycle. It is possible to identify the start and end points of the activity envelope associated with the rhythmic contraction of the muscles and define the timing of the muscle activation cycle relative to heel strike. The metronome was found to be useful to control the pace of natural walking in this study. The surface EMG signal of the first recording minute (1 ~ 2 minute) was not associated with a signal that was stable in terms of the parameters that were used in this study. It wa s found that the last recording minute (9 ~ 10 minute) can be used. This suggests that it may be necessary for subjects to walk for a defined period lasting some minutes before the commencement of recording of the surface EMG. Surface EMG may be used as a tool to measure activation patterns of the low back muscles during muscle contraction associated with the support of various static postures or during the execution of dynamic movements such as walking in the real world. The static postures used in this thesis to record the surface EMG signal from the lumbar paraspinal muscles were found not to provide the basis for a reliable and valid tool. However, a walking exercise might be an alternative activity which can be used easily in clinical practice. The components of the surface EMG signal that may be used in future studies might include measures of the amplitude, frequency and timing of the surface EMG signal.
765

HIGH FREQUENCY (1000 HZ) TYMPANOMETRY AND ACOUSTIC REFLEX FINDINGS IN NEWBORN AND 6-WEEK-OLD INFANTS

Rafidah Mazlan Unknown Date (has links)
Tympanometry and acoustic stapedial reflex (ASR) are routinely used in audiology clinics to assess the functional integrity of the eardrum and middle ear system in humans. Conventional tympanometry (which delivers a probe tone of 226 Hz into the ear canal and measures the mobility of the eardrum as the air pressure in the ear canal is varied) and acoustic reflex testing are effective in detecting middle ear pathologies in children and adults. However, the clinical application of these two tests to infants younger than 7 months has major limitations. In recent years, high frequency tympanometry (HFT) with a probe tone of 1000 Hz has been trialled successfully in young infants (< 7 months) and research on ASRs as they apply to this age group is continuing. Although preliminary HFT data for this population are emerging, there has been no detailed study that describes the effect of age on HFT and ASR results, no clear guideline on ways to interpret the HFT results, and no investigation to measure the feasibility and reliability of the ASR findings. For these reasons, systematic investigation into the use of HFT and ASR measures for evaluating the middle ear function of young infants is warranted. This thesis aimed to: (i) investigate the feasibility of obtaining HFT and ASR findings from newborn and 6-week-old infants, and study the characteristics of the immittance findings in these two age groups; (ii) investigate methods within HFT to measure the middle ear admittance of newborn babies; (iii) establish normative HFT data from healthy newborn babies using the new component compensation method; (iv) examine the test-retest reliability of the ASR test in healthy neonates; and (v) investigate the test-retest reliability of the ASR test in 6-week-old infants. The aims of the thesis were met through five studies. In study one (Chapter 2), a pilot study was conducted to examine the feasibility of performing HFT and ASR in 42 healthy infants and study the characteristics of the immittance findings obtained from these infants using a longitudinal study design. In this pilot study, all infants were tested at birth and then re-tested approximately 6 weeks after the first test. This study confirmed the feasibility of obtaining valid immittance findings from healthy young infants. Most importantly, the findings of this pilot study revealed that the mean values of the majority of HFT parameters and acoustic stapedial reflex threshold (ASRT) obtained at 6 weeks were significantly greater than those obtained at birth, indicating the need to have separate sets of normative data for both tests for newborn and 6-week-old infants. In study 2 (Chapter 3), three different methods to measure middle ear admittance (often described as peak compensated static admittance) in 36 healthy neonates were compared. The three methods were the traditional baseline compensation method (compensated for the susceptance component at 200 daPa pressure) and two new component compensated methods (compensated for both the susceptance and conductance components at 200 daPa and -400 daPa). The results showed that the mean middle ear admittances obtained by compensating for the two components of admittance at a pressure of 200 daPa (YCC200) and -400 daPa (YCC-400) were significantly greater than that using the traditional baseline compensation method (YBC). The higher mean admittance results obtained using the new component compensated methods suggests that the two new methods have the potential to better separate normal from abnormal admittance results. The test-retest reliability of YBC, YCC200 and YCC-400 was investigated, with the result that a lower test-retest reliability was obtained for YCC-400 than for the other two measures. It was, therefore, concluded that the component compensation method compensated at 200 daPa may serve as an alternative method for estimating middle ear admittance, especially in the context of assessing neonates using HFT. In study 3 (Chapter 4), normative data were gathered using the new component compensation method (compensated at 200 daPa) on a group of 157 healthy newborn babies. In addition to the component compensated static admittance (YCC), normative data showing the 90 % ranges for tympanometric peak pressure, admittance at 200 daPa, uncompensated peak admittance, and traditional baseline compensated static admittance (YBC) were established in this study. No gender effect was found on any of the tympanometric measures. In study 4 (Chapter 5), the use of ASR to evaluate middle ear function in neonates was studied. The feasibility of obtaining ipsilateral ASR from neonates by stimulating their ears with a 2 kHz tone and broadband noise (BBN) was demonstrated. ASRs were elicited from 91.3% of 219 full-term normal neonates, while the remaining 8.7% of neonates who had flat tympanograms and no transient evoked otoacoustic emissions did not exhibit ASRs. Good test-retest reliability was demonstrated in the ASRT obtained using both the 2 kHz and BBN stimulus; there was no significant difference between test and retest conditions and intra-correlation coefficients of 0.83 for the 2 kHz tone and 0.76 for the BBN stimulus. In the last study (Chapter 6), the test-retest reliability of ASRT obtained from 70 6-week-old infants was investigated. The methodology described in Chapter 5 was followed. No significant difference in ASRT between test and retest conditions was found for the 2 kHz tone (mean ASRT = 67.3 dB HL versus 67.1 dB HL) and BBN stimulus (mean ASRT = 80.9 dB HL versus 81.6 dB HL). Good test-retest reliability of ASRT with intra-correlation coefficients of 0.78 was found for both the 2 kHz tone and the BBN stimulus. In essence, through achieving the aforementioned aims, the current research program was able to enhance the minimal literature available concerning the use of HFT and ASR testing in young infants. Ultimately, the findings presented in this thesis will inform clinicians of the recent developments in HFT and ASR testing, and assist them in evaluating the middle ear function of young infants with accuracy and confidence.
766

Analysis of Thick Laminated Composite Beams using Variational Asymptotic Method

Ameen, Maqsood Mohammed January 2016 (has links) (PDF)
An asymptotically-exact methodology is presented for obtaining the cross-sectional stiffness matrix of a pre-twisted, moderately-thick beam having rectangular cross sections and made of transversely isotropic material. The beam is modelled with-out assumptions from 3-D elasticity. The strain energy of the beam is computed making use of the constitutive law and the kinematical relations derived with the inclusion of geometrical nonlinearities and initial twist. Large displacements and rotations are allowed, but small strain is assumed. The Variational Asymptotic Method (VAM) is used to minimize the energy functional, thereby reducing the cross section to a point on the reference line with appropriate properties, yielding a 1-D constitutive law. In this method as applied herein, the 2-D cross-sectional analysis is performed asymptotically by taking advantage of a material small parameter and two geometric small parameters. 3-D strain components are derived using kinematics and arranged as orders of the small parameters. Warping functions are obtained by the minimisation of strain energy subject to certain set of constraints that renders the 1-D strain measures well-defined. Closed-form expressions are derived for the 3-D non-linear warping and stress fields. The model is capable of predicting interlaminar and transverse shear stresses accurately up to first order.
767

Galileos påverkan på snabb statisk mätning vid korta baslinjer

Eklund, Per, Olofsson, Elias January 2018 (has links)
Global Navigation Satellite System (GNSS) är ett system för global satellitpositionering och navigering och innefattar bland annat Global Positioning System (GPS) och Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS), dessa två system är de enda fullt globala operativa systemen i dagsläget. Galileo är ett europeiskt satellitsystem under utveckling och erbjuder för närvarande 14 satelliter, men ska bestå av totalt 30 satelliter när systemet beräknas vara fullt fungerande 2020. Den mätmetod med GNSS som har lägst osäkerhet är statisk mätning. Det är en relativ metod vilket innebär att minst två mottagare samlar observationer samtidigt, vanligtvis i flera timmar. Snabb statisk mätning är en vidareutveckling av statisk mätning och erbjuder mycket kortare observationstider, däremot innebär det en begränsning på baslinjelängden. Syftet med denna studie var att undersöka Galileos påverkan vid snabb statisk mätning och se huruvida Galileo kan bidra med lägre osäkerheter, avvikelser och observationstider i olika konstellationer tillsammans med GPS och GLONASS. Mätningarna utfördes under två dagar i fyra respektive två timmar. Två baslinjer mättes; ena baslinjen hade en längd på 0,4 km och den andra på drygt 2 km. I ett bearbetningsprogram delades därefter konstellationerna upp i tio tidsfönster (epoker) och varje tidsfönster delades i sin tur upp i tre sessioner (1, 5 och 10 minuter). Fyra typer av konstellationer testades: GPS, GPS och GLONASS, GPS och Galileo och sist alla tre tillsammans. Resultatet i studien visar på låga osäkerheter när fler än en konstellation används. Lägst osäkerhet uppnås generellt när mätning med alla konstellationer görs. Mätning med endast GPS ger högst osäkerhet i samtliga fall, men detta är framförallt kännbart vid den kortaste sessionen (1 minut). Likheten i osäkerheterna vid den korta och långa baslinjen är tydlig, men osäkerheterna är större för den långa baslinjen. Avvikelserna är lägst med alla konstellationer, men baslinjelängden är i nästan alla fall för kort mot sin referens. Slutsatsen från studien är att Galileo kan användas för att minska observationstider och osäkerheter vid snabb statisk mätning. Detta är dock försumbart ifall GPS och GLONASS redan används, åtminstone för de två baslinjerna i detta test. Låga osäkerheter uppnås antingen med multi-konstellation eller längre observationstider. / Global Navigation Satellite System (GNSS) is a global system for satellite positioning and navigation and consists, amongst other, of Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS). Currently, these systems are the only fully global operative satellite systems for positioning. Galileo is an upcoming satellite system and offers at the present time 14 active satellites, but will consist of 30 satellites once it is fully operational by 2020. The survey method with GNSS that has lowest uncertainties is static survey. It is a relative method which means that a minimum of two receivers observe simultaneously, usually for several hours. Rapid static surveying is a further development of static surveying and offers much shorter observation times, but it imposes a restriction of the baseline length. The purpose of this study is to evaluate Galileo’s contribution on rapid static surveying and see whether Galileo can decrease uncertainties, deviations and observation times in different constellations with GPS and GLONASS. Measurements were conducted during two days for two and four hours respectively. Two baselines were measured; the first baseline had a length of 0.4 km and the second nearly 2 km. Later in a software, each constellation was divided in ten time windows (epochs) and each time window was then divided in three sessions (1, 5 and 10 minutes). Four types of constellations were tried: GPS, GPS and GLONASS, GPS and Galileo and lastly all three combined. Results show that low uncertainties are obtained when more than one constellation is used. Lowest uncertainties can be obtained with all constellations active. Surveying with only GPS gives the highest uncertainties in all cases, but this is especially true for the shortest session (1 minute). Similarities in uncertainties between the short and long baseline is clear, but uncertainties are higher for the long baseline. Deviations are lower with all constellations active, but the baseline length is in almost all cases too short. The conclusion from the study is that Galileo can be used to lower observation time and uncertainties. However this is negligible when used with GPS and GLONASS, at least for the two baselines in this test. Low uncertainties can be achieved with multi constellation or longer observation time.
768

Controle de válvulas de sucção de compressores de refrigeração usando limitador de abertura /

Cavalheiro Júnior, Milton Cesar. January 2017 (has links)
Orientador: José Luiz Gasche / Resumo: A maioria dos sistemas de refrigeração por compressão de vapor utiliza compressores alternativos, considerados mecanismos importantes na era moderna. O ciclo de operação de um compressor alternativo é descrito por uma série de fenômenos complexos ocorrendo em um curto período de tempo. Dentre os fatores considerados importantes para e ciência termodinâmica dos compressores, destacam-se as válvulas que controlam os processos de sucção e de descarga, que são responsáveis por grandes perdas termodinâmicas no ciclo. Parte das perdas ocorre no sistema de válvulas, particularmente na válvula de sucção, onde as instabilidades do seu movimento reduzem a e ciência do processo de sucção. Como uma forma de reduzir os problemas gerados pelas instabilidades no funcionamento da válvula de sucção, propomos a utilização de um esbarro para limitar a abertura máxima da válvula, reduzindo sua instabilidade e aumentando a e ciência do compressor. Mostramos experimentalmente que existe uma posição de equilíbrio que mantém a válvula aberta sem instabilidades e que esta posição varia, aproximadamente, linearmente com o número de Reynolds. / Mestre
769

Le domaine abstrait des polyèdres revisité : représentation par contraintes et preuve formelle / Revisiting the abstract domain of polyhedra : constraints-only representation and formal proof

Fouilhé, Alexis 15 October 2015 (has links)
Cette thèse revisite de deux manières le domaine abstrait des polyèdres utilisé pour l'analyse statique de programmes.D'abord, elle montre comment utiliser l'assistant à la preuve Coq pour apporter des garanties sur la correction des opérations sur les polyèdres sans compromettre l'efficacité de l'outil VP Lissu de ces travaux.L'outil est fondé sur le principe de la vérification de résultats :un oracle, auquel on ne fait pas confiance, fait les calculs,puis les résultats sont vérifiés par un validateur dont la correction est prouvée avec Coq. De plus, l'oracle fournit des témoins de la correction des résultats afin d'accélérer la vérification.L'autre caractéristique de VPL est l' utilsation de la seule représentation par contraintes des polyèdres,par opposition à l'approche habituelle qui consiste à utiliser à la fois des contraintes et des générateurs.Malgré ce choix inhabituel,les performances de VPL s'avèrent compétitives.Comme on pouvait le prévoir,l'opérateur "join",qui calcule l'enveloppe convexe de deux polyèdres,est le plus coûteux.Puisqu'il nécessite un grand nombre de projections,cette thèse explore plusieurs nouvelles approches de l'opérateur de projection,basées sur la programmation linéaire paramétrique.Elle propose une synthèse des variantes et des combinaisons possibles.La thèse se termine sur les éléments clés d'un nouvel algorithme de résolution tirant parti des spécificités de l'encodage afin d'obtenir de bonnes performances. / The work reported in this thesis revisits in two waysthe abstract domain of polyhedraused for static analysis of programs.First, strong guarantees are provided on the soundness of the operationson polyhedra,by using of the Coq proof assistant to check the soundness proofs.The means used to ensure correctnessdon't hinder the performance of the resultingVerimag Polyhedra Library (VPL).It is built on the principle of result verification:computations are performed by an untrusted oracleand their results are verified by a checkerwhose correctness is proved in Coq.In order to make verification cheap,the oracle computes soundness witnesses along with the results.The other distinguishing feature of VPL is thatit relies only on the constraint representation of polyhedra,as opposed to the common practice of using both constraints and generators.Despite this unusual choice,VPL turns out to be a competitive abstract domain of polyhedra,performance-wise.As expected, the join operator of VPL,which performs the convex hull of two polyhedra,is the costliest operator.Since it builds on the projection operator,this thesis also investigates a new approach toperforming projections,based on parametric linear programming.A new understanding of projection encoded asa parametric linear problem is presented.The thesis closes on a progress report in the design of a new solvingalgorithm,tailored to the specifics of the encodingso as to achieve good performance.
770

Mecanismos de transferência de carga em estacas escavadas em solos arenosos através de provas de carga instrumentadas

Sestrem, Liamara Paglia January 2018 (has links)
A experiência acumulada quanto à análise do comportamento de fundações, em relação aos diversos perfis de solos, vem confirmando a necessidade de realizar ensaios em verdadeira grandeza para avaliação de desempenho desses elementos. Aplicação de metodologias empíricas e semi-empíricas, limitadas à prática construtiva regional e às condições específicas que contemplaram o seu estabelecimento, resultam em incertezas nos métodos de previsão e dispersão entre valores de capacidade de carga medidos e previstos. Com base nessas evidências, os ensaios de prova de carga representam a técnica mais comumente empregada para previsão e avaliação da capacidade de suporte em estacas. Como resultado, obtém-se uma curva carga versus deslocamento a partir de um carregamento estático no topo do elemento. Quando executadas em estacas instrumentadas ao longo do fuste, permitem avaliar a mobilização (transferência) de resistências (cargas) ao longo da profundidade e dos carregamentos. Alternativamente, o uso de células expansivas bidirecionais, comumente denominadas de “O-cell”, vem crescendo em nível internacional e confirmando seu potencial de aplicação, embasado por vantagens que incluem a ausência de um sistema de reação e a obtenção de forma direta da resistência de ponta e atrito lateral durante os carregamentos. No intuito de contribuir para uma melhor compreensão dos mecanismos de transferência de carga envolvidos em ensaios estáticos, o presente estudo comparou resultados dessas duas metodologias através de três de ensaios estáticos convencionais e um bidirecional realizados em duas estacas escavadas de grande diâmetro em areia. A distribuição dos carregamentos medidos em função do deslocamento em termos de carga total e de atrito lateral ao longo desses quatro ensaios caracterizou-se por resultados similares. Pequenas diferenças foram observadas entre o ensaio de topo e bidirecional executados em um mesmo elemento de fundação e estão possivelmente associadas aos diferentes níveis de deformação obtidos com as duas técnicas. As condições de limpeza e integridade da ponta em estacas moldadas in loco estão associadas a incertezas ainda que os procedimentos usuais de controle e limpeza tenham sido executados. Divergências entre a parcela de contribuição de ponta ao longo dos ensaios avaliados podem estar associadas a esses fatores e a pequenas variações da geometria descritas em detalhes no trabalho. Deformações medidas pelos strain gages instalados ao longo do fuste da estaca permitiram avançar no entendimento dos mecanismos de transferência de carga existentes durante os carregamentos impostos. Os resultados indicam que o atrito começa a ser mobilizado desde os primeiros incrementos de carga e permanece se desenvolvendo com o aumento das deformações que não são constantes ao longo da profundidade. O comportamento medido ao longo do fuste varia em função do nível de confinamento e ainda da densidade relativa do solo subjacente. Os resultados permitem concluir também que ainda que existam esforços residuais atuantes, sua ordem de grandeza não reflete mudanças importantes no comportamento de elementos de fundação moldados in loco. / The gained experience in foundations behavior analysis on different soil profiles confirms the need to perform tests on full-scale elements to evaluate pile performance. Application of empirical and semi-empirical methodologies, limited to the regional constructive practice and the specific conditions that led to its establishment, result in uncertainties in the prediction and dispersion methods between measured and predicted load capacity values. Based on these evidences, the load tests represent the most commonly used technique for predicting and evaluating pile capacity. As a result, a load versus displacement curve is obtained from a static load at the top of the element. When carried out in piles instrumented along the shaft, it is possible to evaluate the mobilization (transfer) of resistances (loads) along the depth and the loads. Alternatively, the use of bidirectional expansive cells, commonly referred to as "O-cell", has been growing internationally, which confirms its potential, based on advantages that include the absence of a reaction system and obtaining the toe resistance and lateral friction directly during loading. In order to contribute to a better understanding of the load transfer mechanisms involved in static loading tests, the present study compared the results of these two methodologies through three conventional and one bidirectional load tests carried out on two large diameter bored piles. The distribution of loadings measured as a function of the displacement in terms of total load and lateral friction over these four tests was characterized by similar results. Small differences were observed between conventional top-down and bidirectional tests performed on the same foundation member and are possibly associated with the different deformation levels obtained with the two techniques. Cleaning conditions and pile toe integrity in bored piles are associated with uncertainties even though the usual control and cleaning procedures have been performed. Divergences between the contributions of the pile toe resistance along the evaluated tests may be associated with these factors and small variations of the geometry. Deformations measured by the strain gages installed along the pile shaft allowed improving the understanding of the load transfer mechanisms during the loading procedures. The results indicate that shaft friction begins to be mobilized since the first load increments and continues to increase with the strains, which are not linear along the pile shaft. The behavior measured along the shaft is a function of vertical effective stress and relative density. The results also show that although there are active residual stresses, their magnitude does not reflect important changes in the behavior of bored piles.

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