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Kim, Myoung-Ho. "Analysis of Osterberg and Statnamic axial load testing and conventional lateral load testing." [Gainesville, Fla.] : University of Florida, 2001. http://etd.fcla.edu/etd/uf/2001/anp1033/MASTER.pdf.
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Thesis (M.E.)--University of Florida, 2001.Title from first page of PDF file. Document formatted into pages; contains xii, 165 p.; also contains graphics. Vita. Includes bibliographical references (p. 164).
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Butz, Travis M. "Tests on pultruded square tubes under eccentric axial load." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/21800.
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Lau, Hin Chung. "Development of a multi-axial load distribution measurement device." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24966.
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Diabetic foot ulceration is a global health problem that often leads to amputation. While peripheral vascular disease and neuropathy are common risk factors for foot ulcers, excessive mechanical stress would directly cause the breakdown of plantar tissue. Once the skin is broken, many factors may contribute to defective healing and putting one at greater risk for ulceration. Clinical measurement of plantar pressure distribution, therefore, is commonly used to identify feet at risk of ulceration. However, plantar pressures are poor predictors and there is evidence that shear load is at least equally important in ulcer development. Compared to the numerous commercial systems available for plantar pressure distribution measurement, only a few experimental devices exist for shear distribution measurement. These are typically either too large for high spatial resolution measurement or expensive to manufacture, limiting their suitability for routine clinical use. The aim of this study was to develop a low-cost multi-axial load transducer array to measure the distribution of stress beneath the human foot during walking. A preexisting piezoelectric-based load transducer and several novel transducer designs using hydraulic, optoelectronic and magnetic-based technologies were manufactured and their performance relative to 29 criteria evaluated. The magnetic-based design was found to possess the highest performance (accuracy <3%RC, hysteresis <4%RC, non-linearity <2%RC) and physical characteristics (sensing area 10x10mm). Subsequently, an array consisting of 20 discrete magnetic-based transducers was constructed. In a single subject trial, the total shear load measured by the array was <2N of that measured by a Kistler® force platform. Although the array was capable of measuring biaxial shear load distribution, further work is required to expand the current design to measure load distribution beneath the entire plantar surface. Once realised, such a system has the potential to provide valuable biomechanical data that may help clinicians identify diabetic feet at risk of ulceration.
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Shope, Ronald L. "Response of Wide Flange Steel Columns Subjected to Constant Axial Load and Lateral Blast Load." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29521.
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The response of wide flange steel columns subjected to constant axial loads and lateral blast loads was examined. The finite element program ABAQUS was used to model W8x40 sections with different slendernesses and boundary conditions. For the response calculations, a constant axial force was first applied to the column and the equilibrium state was determined. Next, a short duration, lateral blast load was applied and the response time history was calculated. Changes in displacement time histories and plastic hinge formations resulting from varying the axial load were examined. The cases studied include single-span and two-span columns. In addition to ideal boundary conditions, columns with linear elastic, rotational supports were also studied. Non-uniform blast loads were considered. Major axis, minor axis, and biaxial bending were investigated. The effects of strain rate and residual stresses were examined. The results for each column configuration are presented as a set of curves showing the critical blast impulse versus axial load. The critical blast impulse is defined as the impulse that either causes the column to collapse or to exceed the limiting deflection criterion.
A major goal of this effort was to develop simplified design and analysis methods. To accomplish this, two single-degree-of-freedom approaches that include the effects of the axial load were derived. The first uses a bilinear resistance function that is similar to the one used for beam analysis. This approach provides a rough estimate of the critical impulse and is suitable only for preliminary design or quick vulnerability calculations. The second approach uses a nonlinear resistance function that accounts for the gradual yielding that occurs during the dynamic response. This approach can be easily implemented in a simple computer program or spreadsheet and provides close agreement with the results from the finite element method.Ph. D.
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Usman, Irfan-ur-rab. "Rotary-axial spindle design for large load precision machining applications." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/30163.
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Normal stress electromagnetic actuators can be used as both an axial bearing and an in-feed motor in precision machine tool applications that require only millimeter-range axial stroke, such as silicon wafer face grinding or meso-machining. The rotary cutting stage may be integrated with the axially-feeding stage in a rotary-axial architecture. This typology allows the use of independent rotary and axial actuators acting on a single moving mass, rather than an axial actuator moving an entire rotary motor assembly in the feed direction as in typical machine tool architectures. Non-collocated resonances are therefore minimized and thrust and radial stiffness is increased through the elimination of intermediate lateral and thrust bearings, and achievable closed loop positioning performance is improved.
This thesis presents the working principle, design, and analysis of radially-biased electromagnetic bearing/actuators for large load precision rotary-axial spindle applications, and the integration of such an actuator in a full scale prototype to be used as a silicon wafer face grinder. The experimental results indicate that the rotary-axial spindle with radially-biased thrust bearing/actuator is capable of achieving less than 7 nm resolution over a 1.5 mm axial stroke, a worst case load capacity of approximately 5000 N and a best case load capacity of over 8000 N, with rotary-axial coupling of less than 30 nm axial error at 3000 rpm.
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Mohammed, Abdul Waheed. "Effects of Axial Component of Prestress in Load Balancing Method." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/802.
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Post-Tensioned concrete structures can be analyzed using different methods. One of these methods is the load balancing method introduced by T. Y. Lin. This method, unlike conventional stress methods, assumes pre-stress as a form of loading that counteracts the dead loads, live loads and service loads. Basically, the prestressing force is resolved into vertical and horizontal components and then the structure is analyzed as an ordinary loaded structure. The aim of this study is to investigate the effect of horizontal component of prestressing force in frames of different lengths. The horizontal component in beam-like structures will not affect the vertical reactions of the supports or bending moments of the beam. However, neglecting this component in frames can cause significant difference in the actual results. SAP2000 was used to analyze the frames by applying prestress forces directly and then by using balancing loads with and without considering the horizontal component of the prestressing force.
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Rahman, Muhammad Motiur. "Geopolymer concrete columns subjected to axial load and biaxial bending." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/1410.
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This thesis focuses on the behaviour of fly ash based geopolymer concrete columns under axial load and biaxial bending. Tests showed that failure load of columns increased with the increase of concrete compressive strength and longitudinal reinforcement ratio, and decreased with the increase of load eccentricity. Use of the Bresler’s reciprocal load formula with an iterative procedure for slender columns in uniaxial bending conservatively predicted the strength of the test columns.
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Boggs, Thomas P. "Determination of axial load and support stiffness of continuous beams by vibration analysis." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-11102009-020304/.
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Da, Silva Pedro. "Effect of concrete strength on axial load response of circular columns." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0030/MQ64216.pdf.
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Li, Xinrong. "Reinforced concrete columns under seismic lateral force and varying axial load." Thesis, University of Canterbury. Civil Engineering, 1994. http://hdl.handle.net/10092/7593.
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The project is carried out with the intention to study the strength and ductility of reinforced concrete columns subjected to simulated seismic horizontal loading and varying axial load.
First, an extensive review of previous research on the behaviour of reinforced concrete members and hysteretic modelling is provided.
Then, the experimentally investigation which involves testing a total of nine reinforced concrete specimens under simultaneously cyclic lateral loading and varying axial load is carried out. The first series of six reinforced concrete column units were tested to obtain the variations in flexural hysteretic behaviour with fluctuation in axial load level. In the second phase of experimental investigation, three specimens were tested to study the shear strength of reinforced concrete columns subjected to cyclic lateral loading and varying axial load with emphasis placed on the study of degrading concrete shear resisting mechanisms and comparisons with the present design code equations for shear strength.
Following the experimental program, the mechanisms of shear resistance and the factors affecting the shear strength are considered. In particular, the effects of alternating tension and compression axial load on the shear resisting mechanisms are studied. On the basis of experimental results, proposals are made for predicting shear strength of reinforced concrete column of ductility and limited ductility.
Next, the theoretical work was undertaken to investigate the elastic and post-yield flexural rigidities of reinforced concrete sections. The equations for determining the elastic and post-yield flexural regidities are presented. Also, a moment-curvature hysteretic model including varying axial loading effect is proposed. The theoretical predictions for the moment-curvature hysteresis relationship were found to compare well with the experimental results.
Finally, an example is given of inelastic dynamic response analysis of reinforced concrete frame using the proposed moment-curvature model which includes the effects of varying axial load on the yield moment, and loading and unloading stiffness of the structural members.
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Paggett, Jon W. "Neutron diffraction study of load response and residual stresses in WC-(Ni/Co) composites." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4109.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 25, 2006) Vita. Includes bibliographical references.
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Yang, Li. "Behaviour of masonry columns of geometric section subjected to eccentric axial load." Thesis, University of Manchester, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705160.
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Costa, d'Aguiar Sofia. "Numerical modelling of soil-pile axial load transfer mechanisms in granular soils." Châtenay-Malabry, Ecole centrale de Paris, 2008. http://www.theses.fr/2008ECAP1075.
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L’objectif du travail présenté dans cette thèse est l'analyse et modélisation numérique des mécanismes de transfert de charge axiale entre sol-pieu, dans les sols granulaires. En utilisant un modèle élastoplastique tridimensionnel d'élément finis, une attention particulière est prêtée à la modélisation du comportement de l’interface sol-structure. Ainsi, les outils numériques nécessaires ont été mis en place et les outils existants ont été améliorés afin que, l'analyse de l'interaction sol-pieu soit faisable. Deux nouveaux modèles de comportement 3D sont implémentés dans le code d'éléments finis GEFDYN: un modèle d'interface et, pour le sol, une formulation axisymétrique du modèle multimécanismes de l’ECP, déjà existant et également connus sous le nom de Hujeux. La performance des deux modèles de comportement est comparée avec des résultats expérimentaux: d'abord, en utilisant des essais directs de cisaillement sol-structure et ensuite des essais de charge statiques de pieux en modèle physiques de centrifugeuse. La formulation théorique et l'exécution numérique des modèles constitutifs se sont donc avérées adéquats pour l'analyse des mécanismes de transfert de charge de sol-pieux, pour différents états initiaux du sol, différentes rugosités de la surface sol-pieux et différentes géométries. Finalement, l'applicabilité des modèles proposés est également étudiée pour un cas d’étude réel d’essais de charge statique de pieux forés et à tarière continus, menés dans le site expérimental ISC2 à l’occasion de la 2nd International Conference on the Site Characterization. L’identification des paramètres du sol et la simulation des essais de charge in-situ a été réalisé avec succésThe purpose of the work presented in this thesis, which has a theoretical and numerical character, is the analysis and numerical modelling of soil-pile load transfer mechanisms, in granular soils, when the pile is subjected to axial vertical loads. In the three dimensional elastoplastic finite element model used, particular attention is paid to modelling soil-structure interface behavior. The necessary numerical tools were implemented and the existing ones enhanced so that, the analysis of the soil-pile interaction problem is feasible. Two newly implemented 3D constitutive laws, in the GEFDYN finite element code, are proposed: an interface model and, for soil, an axisymmetric formulation of the existing ECP multimechanism model, also known as Hujeux model. The performance of both constitutive models is compared with experimental results. First, using soil-structure direct shear tests and then, using results of static pile load tests of centrifuge physical models. The theoretical formulation and numerical implementation of the constitutive models proved to be adequate for the analysis of the soil-pile load transfer mechanisms for different soil initial states, soil-pile surface roughness conditions, and different geometries. Finally, the applicability of the proposed models, is also studied for a real case study of pile static load tests carried out in the ISC'2 experimental site, at the occasion of the 2nd International Conference on the Site Characterization. Soil’s laboratory characterization tests and in-situ pile static load tests on bored and CFA piles are simulated, and results successfully compared
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Lam, Sze Yue. "Effects of axial load, shielding and shape on negative skin friction on piles /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202006%20LAM.
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England, Melvin Gerrard. "A pile behaviour model." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311976.
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Gibb, John Michael. "Evaluation of resistance to permanent deformation in the design of bituminous paving mixtures." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318643.
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Müller, Matthias. "Predicting the ultimate axial load capacity of joints formed using V-band retainers." Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/12144/.
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V-band retainers are widely used in the automotive, aircraft and aerospace industries to connect a pair of circular flanges to provide a joint with good axial strength and torsional rigidity. V-band retainers are manufactured using a cold roll forming process. Despite their wide application, once assembled to a pair of flanges little is known about the interaction between flange and band. Moreover the failure mode of V-band retainers when applying an axial load is not fully understood. In this thesis the ultimate axial load capacity of V-band retainers is predicted using finite element and theoretical models and validated using experimental testing. It was shown that the ultimate axial load capacity was strongly dependent on the joint diameter, increasing between 114mm and 235mm, and decreasing beyond that. Moreover, the peak in ultimate axial load capacity was dependent on parameters such as the axial clamping load and coefficient of friction, and its position lay between 235mm and 450mm, as predicted by the finite element models. Other geometrical parameters such as flange and band thickness showed large impacts on the ultimate axial load capacity as well. A theoretical model was developed that allowed the ultimate axial load capacity to be calculated from a single formula for larger bands and using a simple algorithm for smaller bands. This model supported the findings that, depending on the band diameter, the ultimate axial load capacity had a peak, but predicted its position at approximately 181mm. This position at 181mm was validated by the experimental data. However, when compared to the tests, the finite element and theoretical models both over-predicted the ultimate axial load capacity. Both the finite element models and practical tests showed that for small V-bands axial failure is due to a combination of section deformation and ring expansion, whereas large V-bands fail due to ring expansion only. These two distinct types of behaviour were incorporated into the theoretical model. The hardness development throughout the cold roll forming process was predicted using finite element models. This was validated by hardness measurements, for which a new technique was generated, that directly linked plastic strain and hardness values.
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Sun, Miao. "Use of Material Tailoring to Improve Axial Load Capacity of Elliptical Composite Cylinders." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29693.
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This study focuses on the improvement of the axial buckling capacity of elliptical composite cylinders through the use of a circumferentially-varying lamination sequence. The concept of varying the lamination sequence around the circumference is considered as a viable approach for off-setting the disadvantages of having the cylinder radius of curvature vary with circumferential position, the source of the reduced buckling capacity when compared to a circular cylinder with the same circumference. Post-buckling collapse behavior and material failure characteristics are also of interest. Two approaches to implementing a circumferential variation of lamination are examined. For the first approach the lamination sequence is varied in a stepwise fashion around the circumference. Specifically, each quadrant of the cylinder circumference is divided into three equal-length regions denoted as the crown, middle, and side regions. Eight different cylinders designs, whereby each region is constructed of either a quasi-isotropic or an axially-stiff laminate of equal thickness, are studied. Results are compared to the baseline case of an elliptical cylinder constructed entirely of a quasi-isotropic laminate. Since the thickness of the quasi-isotropic and axially-stiff laminates are the same, all cylinders weight the same and thus comparisons are meaningful. Improvements upwards of 18% in axial buckling capacity can be achieved with one particular stepwise design. The second approach considers laminations that vary circumferentially in a continuous fashion to mitigate the effects of the continuously-varying radius of curvature. The methodology for determining how to tailor the lamination sequence circumferentially is based on the analytical predictions of a simple buckling analysis for simply-supported circular cylinders. With this approach, axial buckling load improvements upwards of 30% are realized. Of all the cylinders considered, very few do not exhibit material failure upon collapse in the post-buckled state. Of those that do not, there is little, if any, improvement in bucking capacity. Results for the pre-buckling, buckling, post-buckling, and material failure are obtained from the finite-element code ABAQUS using both static and dynamic analyses. Studies with the code demonstrate that the results obtained are converged.Ph. D.
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Jamaluddin, Norwati. "Behaviour of elliptical concrete-filled steel tube (CFT) columns under axial compression load." Thesis, University of Leeds, 2011. http://etheses.whiterose.ac.uk/11322/.
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This thesis describes a research of the behaviour of the elliptical CFT columns under axial loading. The most substantial part of this research is experimental works conducted on twenty-seven specimens including the hollow stub columns as references. Parameters such as slenderness ratio, uni-axial compressive strength of concrete infill and the aspect ratio were considered to investigate their influence on the behaviour on these columns. The results presented are the first member buckling tests on elliptical CFT columns. Keys results from the tests have been presented and discussed. Parallel with the experimental works, numerical analyses were carried out and verified with the experimental results. Parametric studies were performed following the validation of the numerical models. As there is no design guidance seems to be available in any standard, thus this research provides a review of the existing design standards of Eurocode 4 (EC4) and American Specifications (AISC). The design expressions from these current design provisions for circular, square and rectangular concrete- filled tubes design strengths were used to predict the capacities of elliptical eFT columns. The influences of concrete enhancement, steel reduction due to biaxial effects and column slenderness were all incorporated in design rules of EC4. Based on the experimental, numerical findings the evaluations were made on the design rules of the codes. This investigation was aimed at providing reliable design guidelines for practising engineers to employ the elliptical concrete-infill columns in the construction industry.
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Skvorchevsky, A. Y. "ELS capacity control system for axial-piston pumps." Thesis, Національний технічний університет "Харківський політехнічний інститут", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/46920.
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Wang, Tianjiao. "Feasibility for spinal muscles creating pure axial compressive load or follower load in the lumbar spine in 3-D postures." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1790.
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Previous in-vivo studies showed that compressive force acting on the spine may exceed 2600 N. However, the ligamentous lumbar spine becomes unstable when subjected to compressive loads less than 100 N. It is generally accepted that the ligamentous spine itself is unstable but can be stabilized by muscle forces (MFs) in vivo. Nevertheless, normal spinal muscle contraction patterns remain unknown.
In recent in vitro studies, when the direction of the applied load was controlled along the spinal curvature so that the internal spinal load became perfect compressive follower loads (CFLs) at all lumbar levels, the ligamentous lumbar spine was found to withstand large compressive load (up to 1200 N) without buckling while maintaining its flexibility in neutral or flexed postures. The results of in-vivo animal studies also have shown that shear stress has a more detrimental effect on the rate of disc degeneration compared to compressive stress. These results suggest CFLs in the lumbar spine would be a normal spinal load whereas the transverse (or shear) load abnormal. An initial test of this postulation would be to investigate whether the spinal muscles can create perfect internal CFLs in the lumbar spine in all 3-D postures. In addition, small intrinsic muscles (SIMs) are crucial for better control of the direction of the internal spinal load along the spinal axis was also proposed.
A finite element (FE) model together with an optimization model were used for this study. Both models consist of the trunk, sacrolumbar spine and 244 spinal muscles. Different from other studies, 54 SIMs were also included in the models. The FE model was validated by comparing the ROM of the spine with the literature data. Minimization of the summation of the spinal loads and moments was used as the cost function for the optimization model. The geometrical data obtained from the FE model was used as the input for the optimization model; it was then used to calculate the MFs required for creating the CFLs at all lumbar spine levels. The MFs determined in the optimization model were then imported back to the FE model as input loads to check the stability of the spine under this loading condition. Five different postures were studied: neutral, flexion 40°, extension 5°, lateral bending 30° and axial rotation 10°.
Many optimization solutions for spinal muscle force combinations creating pure CFLs in the lumbar spine were found available in each posture. However, FE analyses showed that only muscle forces and patterns solved at FLPs along the curve in the vicinity of the baseline curve stabilized the lumbar spine. Stability was determined by small displacement of the trunk (less or equal to 5mm) due to small deformation of the lumbar spine. The magnitudes of joint reaction forces (JRFs) predicted from the optimization model were comparable to those reported in the literature. When the SIMs were removed, optimization solutions were still feasible in all five postures, but JRFs and trunk displacement were increased. This suggests the need of SIM inclusion in future spine biomechanics studies and clinically, damages to the SIMs may have a high risk of future spinal problems, such as spinal instability, early disc degeneration, deformity and/or early failure of spinal fixation devices.
The results from this study supported the hypothesis that the perfect CFLs at all lumbar levels could be the normal physiological load under which the lumbar spinal column could support large load without buckling while allowing flexibility. SIMs played an important role in creating CFLs as by including SIMs in the models, the JRFs at all lumbar spine levels were lowered and the stability of the spine was increased.
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Albarazi, Rayan. "Evaluation of Roadway Embankment Under Repetitive Axial Loading Using Finite Element Analysis." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81916.
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Bernat, Masó Ernest. "Analysis of unreinforced and TRM-strengthened brick masonry walls subjected to eccentric axial load." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/145389.
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A significant number of buildings are supported by load-bearing masonry walls. The preservation of these worldwide used structures is a sustainable alternative. However, there is little research about the structural response of these particular elements if compared with others like concrete or steels framed structures. Hence, a further study of the load-bearing masonry walls is necessary as a starting point for the preservation activities.
The load-bearing masonry walls are usually subjected to a vertical eccentric loading condition, which is related with their complex structural response. This response is characterised by the second-order bending effects due to the eccentricity of the load, the non-linear compressive response of the masonry and its almost negligible tensile strength. Thus, strengthening these walls, in order to increase their load-bearing capacity, is an interesting upgrading alternative to enhance their life-cycle.
In this thesis, an experimental campaign has been carried out. It consisted of hundreds of characterisation tests to obtain the mechanical properties of the component materials which have been used to build twenty-nine full-scale walls. Twenty of these walls were unreinforced and the other nine were TRM (Textile Reinforced Mortar) strengthened. All of them have been tested under eccentric compressive loading conditions. The analysis of the strengthened walls has allowed studying the influence of the strengthening mortar type on the load-bearing capacity. The effects using anchors or embedding different types of fibre grids have been also analysed.
A bidimensional (2D) simplified micro-model has been implemented to analyse these structural cases. This numerical tool has been validated using the data from the experimental campaign. Finally, analytical methodologies have been proposed to calculate the load-bearing capacity of unreinforced and TRM-strengthened brick masonry walls. Similarly, two current standards, Eurocode-6 and ACI-530 have been applied to the analysed cases and their results have been compared with the experimental ones.
The results show that the TRM provides a load-bearing capacity increase over 100% and homogenises the structural response, which becomes stiffer. Regarding the simulations, the proposed numerical model provides accurate results, which are better for the cases with larger slenderness or larger eccentricity of the applied load. Finally, the proposed analytical methods provide acceptable results, which are more accurate than the ones obtained by applying the formulations included in the analysed standards.Un nombre significant d'edificis estan suportats per murs de càrrega d'obra de fàbrica. La preservació d’aquestes estructures que s’utilitzen arreu del món is una alternativa sostenible. No obstant això, hi ha molt poca recerca en relació a la resposta estructural d’aquests elements particulars si es compara amb altres com les estructures porticades d’acer o formigó. Per tant, és necessari un major estudi dels murs de càrrega d’obra de fàbrica com a punt de partida de les actuacions de preservació. Normalment, els murs de càrrega estan subjectes a patrons de càrrega vertical excèntrica, cosa que està relacionada amb la seva resposta estructural complexa. Aquesta resposta es caracteritza pels efectes de flexió de segon ordre degut a l’excentricitat de la càrrega, per la resposta no linear a compressió de l’obra de fàbrica i per la seva, pràcticament negligible, resistència a tracció. Per tant, el reforç d’aquests murs, per tal d’augmentar-ne la seva capacitat resistent is una alternativa de millora interessant per allargar la seva vida útil. En aquesta tesi s’ha dut a terme una campanya experimental. Aquesta ha consistit en centenars d’assaigs de caracterització de les propietats mecàniques dels materials components utilitzats per construir vint-i-nou murs. Nou d’aquests es van reforçar amb Textile Reinforced Mortar, TRM, i els altres vint van ser assajats sense reforç. Tots van ser sotmesos a compressió excèntrica. L’estudi dels murs reforçats ha permès analitzar la influència del tipus de morter de reforç, l’efecte de disposar ancoratges o la dependència de la capacitat resistent en el tipus de malla de fibra utilitzada. S’ha implementat un micromodel simplificat bidimensional (2D) per analitzar els casos estructurals proposats. Aquesta eina numèrica ha estat validada utilitzant les dades de la campanya experimental. Finalment, s’han proposat mètodes analítics per calcular la capacitat portant dels murs sense reforç i dels reforçats amb TRM. De forma semblant, s’han aplicat dos normes actuals, l’Eurocodi-6 i l’ACI-530, als casos d’estudi per tal de comparar-ne els resultats amb els experimentals. Els resultats mostren que el TRM aporta un augment de la capacitat resistent de més del 100% i homogeneïtza la resposta estructural que esdevé més rígida. En relació a les simulacions, el model numèric proposat obté resultats acurats, els quals són millors pels casos de major esveltesa o més excentricitat de la càrrega. Per acabar, els mètodes analítics que es proposen aporten resultats acceptables, els quals s’ajusten millor als experimentals que els obtinguts aplicant les formulacions de les normatives.
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Doruk, Koray. "Fiber Reinforced Polymer Confined Rc Circular Columns Subjected To Axial Load And Bending Moment." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607474/index.pdf.
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Fiber reinforced polymers (FRPs) have gained increasing popularity in upgrades of reinforced structural elements due to high strength to weight ratio and ease of application. In this study, the effectiveness of the carbon reinforced polymer wrapping (CFRP) on ductility and strength of circular reinforced concrete columns, made of low strength concrete, is presented. Four circular reinforced columns with similar dimensions, longitudinal and confining steel reinforcement were tested under combined axial load and bending moment. Three specimens were strengthened with CFRP and the results were compared with the control specimen. The main parameter of the experimental study was selected as the level of eccentricity. First of all, the strain profiles of FRPs in the circumferential direction were observed and the confining stress distributions were examined. Then, an axial stress-strain model for FRP confined concrete with a transition from softening to hardening response for different confinement ratios is proposed. The proposed model was verified by comparing the model estimations with the test results obtained from this study and results reported by other researches. In addition, a parametric study was presented to obtain a simple equation to estimate curvature ductility of FRP confined circular columns.
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Su, Bin. "RELIABILITY-BASED OPTIMIZATION OF ANISOTROPIC CYLINDERS WITH RESPONSE SURFACE APPROXIMATION OF AXIAL BUCKLING LOAD." MSSTATE, 2001. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11122001-003524/.
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The reliability analysis and reliability-based optimization of laminated circular cylinders under axial buckling instability are studied. Structural reliability is measured in terms of Hasofer-Lind reliability index. The response surface models are used in both the calculation of the reliability index and the reliability-based optimization. In reliability analysis, both deterministic and probabilistic sensitivity factors are investigated; the results show that the reliability index is most sensitive to the applied load and Young's modulus of the material. Two cases are considered in the optimization study. In the first case, the cylinder weight is minimized subject to a reliability constraint whereas in the second case, cylinder reliability is maximized subject to a weight constraint. In addition, two different optimization techniques are studied. In the first technique, a global response surface model of the buckling response based on 3000 Monte Carlo simulations is used for the design optimization whereas in the second technique, multiple local regression models, with each based on approximately 20 simulations, are used in sequential search of an optimum design. An optimum design is found. The results based on sequential application of multiple local regression models are close to those from global optimization while the former is much more efficient in terms of computational cost.
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Boylan, Matthew Aaron. "Web Crippling Strength of Sigma-Shaped Cold-Formed Steel Studs Subjected to Axial Load." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-06262006-131040/.
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Load-bearing light steel framing (LSF) systems have gained good acceptance to the low to mid-rise construction market in the U.S. in recent years. This construction market covers a wide range of building usage, including apartment and office buildings, hotels, and schools. For years, standard C-shaped metal studs have been the only option for designers and contractors when selecting a cross-section for load bearing studs. As design loads for the studs get larger with heavier floor systems or at lower levels of mid-rise buildings, designers have been required to either use multiple (built-up) C-shaped studs or switch to structural steel members. An alternative to the standard shapes, although seldom found in the U.S., is the sigma-shaped section, but this shape is primarily used as a roof purlin in Europe. The Steel Network, Inc. of Raleigh, North Carolina recognized the potential of this section for use within a LSF system and developed the SigmaStud?. A testing program was developed for the SigmaStud? and testing was conducted at North Carolina State University?s Constructed Facilities Laboratory (CFL). Presented are the results of a series of tests to evaluate the web crippling behavior of a new sigma-shaped metal stud when subjected to lateral load in addition to axial load. Also presented is an analytical study that results in proposed modifications to the AISI web crippling equation to account for sigma-shaped sections with or without axial load.
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Jadid, Mansour Nasser. "The application of neural network techniques to the analysis of reinforced concrete beam-column joints subjected to axial load and bi-axial bending." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/14160.
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The application of neural networks in the form of parameter predictions to the behaviour and strength of beam-column joints under axial load and biaxial bending has been studied. Computation algorithms in the form of numerical analysis were performed on the beam-column joints to simulate the existing experimental data. A systematic approach was provided by implementing neural networks in the form of prediction by backpropagation algorithms. The objective of this study was to demonstrate a concept and methodology, rather than to build a full-scale knowledge-based system model, by incorporating most of the fundamental aspects of a neural network to solve the complex non-linear mapping of a beam-column joint. In general, it should be possible to identify certain parameters and allow the neural network to develop the model, thus accounting for the observed behaviour without relying on a particular algorithm but depending entirely on the manipulation of numerical data. The aim of this study was to view available experimental data on beam-column joint parameters from different angles and establish a concept and methodology that would provide rapid and economic benefits to experimental research. The focus of this study is to reconstruct previous experimental work by evaluating several parameters and establish valid mathematical relationships based on neural networks which are in agreement with relationships based on the experimental results. The computational methodology considered for the analysis of the beam-column joints has been formulated by adopting three stages to establish a procedure to implement the concept and methodology proposed. The procedure is demonstrated by the evaluation of the ultimate flexural strength of the reinforced concrete members, the moment-curvature relationship and the shear strength of the beam-column joint.
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Ryan, Keri Lynn Chopra Anil K. "Estimating the seismic response of base-isolated buildings including torsion, rocking, and axial-load effects /." Berkeley : Earthquake Engineering Research Center, University of California, 2005. http://nisee.berkeley.edu/elibrary/.
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Previously published as first author's thesis (Ph. D. in Engineering--University of California, Berkeley, 2004)."June 2005." Includes bibliographical references. Also available as an electronic document from the Earthquake Engineering Online Archive Earthquake: http://nisee.berkeley.edu/elibrary.
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Juneja, Lokesh Kumar. "Multiaxial fatigue damage model for random amplitude loading histories." Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/41522.
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In spite of many multiaxial fatigue life prediction methods proposed over decades of
research, no universally accepted approach yet exists. A multiaxial fatigue damage
model developed for approximately proportional random amplitude loading is proposed
in this study. A normal strain based analysis incorporating the multiaxial state
of stress is conducted along a critical orientation assuming a constant strain ratio.
The dominant deformation direction is chosen to be the critical orientation which
is selected with the help of a principal strain histogram generated from the given
multiaxial loading history. The uniaxial cyclic stress-strain curve is modified for the
biaxial state of stress present along the critical orientation for the plane stress conditions.
Modified versions of Morrow's and of Smith, Watson, and Topper's (SWT)
mean-stress models are used to incorporate mean stresses. A maximum shear strain
based analysis is, in addition, conducted to check for the shear dominant fatigue
crack growth possibility along the critical direction. The most damaging maximum
shear strain is chosen after analyzing the in-plane and the two out-of-plane shear
strains.
The minimum of the two life values obtained from SWT model and the shear
strain model is compared with the life estimated by the proposed model with the
modified Morrow's mean stress model. The former is essentially the life predicted by
Socie. The results of the proposed model, as reduced to the uniaxial case, are also
compared with the experimental data obtained by conducting one-channel random
amplitude loading history experiments.
Master of Science
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Han, Yi. "Axial load tests and analysis for open-ended steel tubular piles driven into weathered rock." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0006/MQ46582.pdf.
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Al-Rahmani, Ahmed Hamid Abdulrahman. "Shear-flexure-axial load interaction in rectangular concrete bridge piers with or without FRP wrapping." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/18967.
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Doctor of PhilosophyDepartment of Civil Engineering
Hayder Rasheed
Recent applications in reinforced concrete columns, including strengthening and extreme loading events, necessitate the development of specialized nonlinear analysis methods to predict the confined interaction domain of axial force, shear, and bending moment in square and slightly rectangular concrete columns. Fiber-reinforced polymer (FRP) materials are commonly used in strengthening applications due to their superior properties such as high strength-to-weight ratio, high energy absorption and excellent corrosion resistance. FRP wrapping of concrete columns is done to enhance the ultimate strength due to the confinement effect, which is normally induced by steel ties. The existence of the two confinement systems changes the nature of the problem. Existing research focused on a single confinement system. Also, very limited research on rectangular sections was found in the literature. In this research, a model to estimate the combined behavior of the two systems in rectangular columns is proposed. The calculation of the effective lateral pressure is based on Lam and Teng model and Mander model for FRP wraps and steel ties, respectively. The proposed model introduces load eccentricity as a parameter that affects the compression zone size, and in turn the level of confinement engagement. Full confinement corresponds to zero eccentricity, while unconfined behavior corresponds to infinite eccentricity. The model then generates curves for eccentricities within these boundaries. The numerical approach developed has then been extended to account for shear interaction using the simplified modified compression field theory adopted by AASHTO LRFD Bridge Design Specifications 2014. Comparisons were then performed against experimental data and Response-2000, an analytical analysis tool based on AASHTO 1999 in order to validate the interaction domain generated. Finally, the developed models were implemented in the confined analysis software “KDOT Column Expert” to add FRP confinement effect and shear interaction.
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Osorio, Gomez Laura Isabel. "Behavior of synthetic fiber-reinforced concrete circular columns under cyclic flexure and constant axial load." Mémoire, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1435.
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La ductilité et la capacité à dissiper de l'énergie sont deux qualités très importantes pour les éléments structuraux des structures situées dans les régions sismiques comme l'est du Canada. Soulignons que Montréal occupe la deuxieme place en ce qui a trait au risque sismique au Canada. De plus, la réduction des coûts de maintenance des infrastructures est un sujet d'intérêt pour les propriétaries alors que ces derniers doivent en tout temps garantir la sécurité des usagers. Or, le béton renforcé avec des fibres synthétiques semble être un matériau qui remplit ces caractéristiques. Pourtant, son utilisation est actuellement limitée aux éléments non structuraux ou structuraux mais non principaux. Afin de généraliser l'utilisation du béton fibre dans le domaine structural, il faut continuer à produire et à analyser des données expérimentales qui permettront de valider et d'améliorer les prescriptions de design et les modèles analytiques actuels pour la conception des éléments en béton armé avec des fibres dans les zones sismiques. Dans ce contexte, six poteaux circulaires à grande-échelle ont été testés sous une charge axiale constante (25% de Agf'c) et en flexion cyclique. Trois poteaux ont été confectionnés en béton normal (BN) et les trois autres en béton renforcé avec des fibres synthétiques (BRFS). La résistance à la compression du béton spécifiée à 28 jours pour les spécimens était de 30 MPa. Le volume de fibres synthétiques en polypropylène-polyéthylène utilisé a été de 1%. Les trois poteaux en BN étaient renforcés par une armature transversale constituée d'une spirale ayant un pas de 42, 75 et 100 mm respectivement. Ces trois spécimens ont été comparés avec des spécimens similaires en BRFS. Les résultats montrent que la présence des fibres synthétiques dans la matrice de béton améliore le comportement ductile et la capacité a dissiper de l'énergie des spécimens. Il a été observé que cette amélioration n'est pas directement proportionnelle à la quantité d'armature transversale. Toutefois, l'utilisation du béton fibre semble rendre possible une réduction de l'armature transversale tout en conservant un aussi bon sinon un meilleur comportement.
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Leo, Riccardo. "The axial response of offshore piles in sand from large scale tests." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
This thesis focuses on deep foundations used in offshore environment, in particular for offshore wind turbines. Piles are necessary when the bearing capacity of the shallow soil layers is not enough to ensure stability. Piles can work on both axial and lateral response. In the thesis only axially loaded piles will be considered. The analysis of the axial behavior of piles should be considered in terms of ultimate capacity as well as the load transfer mechanism between the pile and the soil.
The technical aim of this thesis concerns the understanding of the load transfer curves, their extrapolation and the exploration of load distribution along the pile during a given load. To achieve this, a thorough study of literature on current design methods is carried out and two instrumented piles will be analysed in order to understand how the load is distributed along the pile shaft and how experimental load transfer curves can be extrapolated.
The more general aim of this work is to optimize design procedures and try to reduce the cost related piles and their installation in offshore environment, since it is quite known to be higher than onshore fields, as it will be explained in the first chapter of this thesis.
A geotechnical software IGtH Pile developed by the Institute of geotechnical Engineering (IGtH), Leibniz Universität Hannover will be used in the evaluation of the ultimate capacity and the results will be compared with a Matlab code developed at the IWES research institute.
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Chau, Siu-lee. "Effects of confinement and small axial load on flexural ductility of high-strength reinforced concrete beams." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31997661.
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Wilmshurst, S. R. "The ultimate load behaviour of multiplanar KK-joints subjected to symmetrical and anti-symmetrical axial loading." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636661.
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This thesis presents the results of a numerical study into the behaviour of CHS steel KK-joints, subjected to symmetrical and anti-symmetrical axial loading, using the Finite Element Method. The objectives were to generate Finite Element data to expand the databases of KK-joints subjected to these two modes of loading and to further understanding of the ultimate load behaviours of these joints over the extended geometrical parameter ranges. This was done in order to aid the future design of multiplanar joints. A valid and accurate Finite Element model was developed and calibrated against existing experimental data. Factors that could influence the static strength, other than the geometry, were considered during the verification of the model. These included the modelling of the weld geometry, boundary conditions, loading modes, and material properties. Parametric studies were then performed to further understand the behaviour of KK-joints under the two loading modes. In total, the results of over 70 symmetrically loaded KK-joints and 35 anti-symmetrically loaded KK-joints are reported. Databases of multiplanar joints under axial loading were compiled using these and the valid test results of other researchers. Also presented are new equations to determine the failure types of symmetrically loaded KK-joints, and equations to differentiate between chord and brace failure modes. An investigation of the database of Mouty and Rondal (1990), was undertaken using Finite Element models and the failure mode equations, to establish the causes of low joint capacities and brace member failures. Using the databases, assessments were made to determine the accuracy of existing prediction equations, which resulted in their modification. Due to the complexity of the ensuing equations, simpler, yet just as effective, empirical prediction equations are proposed for symmetrically and anti-symmetrically loaded KK-joints.
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Chau, Siu-lee, and 周小梨. "Effects of confinement and small axial load on flexural ductility of high-strength reinforced concrete beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31997661.
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ENCISO, ROXANA OLARTE. "BEHAVIOR OF SLENDER HIGH STRENGTH CONCRETE COLUMNS SUBJECTED TO AXIAL LOAD AND BENDING ABOUT ONE AXIS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16425@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste trabalho apresenta um estudo experimental do comportamento de pilares esbeltos de alta resistência submetidos à flexão composta reta. Foram ensaiados oito pilares divididos em duas séries, sendo uma série com concreto de 40 MPa e a outra com concreto de 80 MPa aos vinte e oito dias. Todos os pilares tinham seção transversal de 15x25 cm e altura de 300 cm. Em cada série, a variável foi a taxa de armadura longitudinal que assumiu quatro valores diferentes. O objetivo foi verificar os valores da excentricidade de segunda ordem que devem ser considerados no dimensionamento de pilares esbeltos de concreto de alta resistência. Os resultados dos ensaios foram comparados com os resultados teóricos obtidos pelos modelos da curvatura aproximada e da rigidez aproximada que constam na NBR6118:2003. Essa comparação mostrou uma boa concordância entre os resultados experimentais e teóricos.
This work presents an experimental study of the behavior of slender high strength concrete columns under uniaxial eccentric compression loads. Eight columns were tested, divided into two series, one series with concrete of 40 MPa and the other with concrete of 80 MPa at twenty eight days. All columns had a cross-section of 15x25 cm and height of 300 cm. In each series, the variable was the longitudinal reinforcement ratio which assumed four different values. The objective was to verify the values of the eccentricity of second order that should be taken into account in the design of slender high strength concrete columns. The experimental results were compared with theoretical results obtained by the models of the approximated curvature and approximated stiffnes methods prescribed in the NBR6118:2003 code. This comparison showed a good agreement between the experimental and theoretical results.
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Damaraju, Avinash Sharma. "Investigation on the Stability of Noncompact and Slender Concrete Filled Tubes Subjected to Axial Loads." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin151179557053975.
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Lau, J. C. K. "The strength of masonry walls and columns of geometric cross section subjected to axial load and bending." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705159.
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Schudt, Joseph Anthony. "Identification and response of a nonlinear clamped-clamped beam with an axial tensile load: theory and experiment /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487854314870891.
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Forni, Fabio. "Investigating the axial response of pile foundations for offshore wind turbines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
I crescenti problemi legati ai cambiamenti climatici rendono l'impiego delle energie rinnovabili sempre più interessante.
In questa ottica, in Germania si sta pianificando di aumentare la produzione di energia pulita attraverso lo sfruttamento dell’energia eolica. Nuovi impianti di turbine eoliche sono previsti nel Mare del Nord in acque medio profonde (25-45m) dove la parte immersa della struttura della turbina eolica (chiamata sottostruttura) è spesso costituita da una struttura jacket (traliccio) o tripod (a treppiedi). Questo tipo di sottostrutture trasmettono principalmente carichi assiali alle fondazioni (in genere fondazioni su palo), e il carico a trazione è la forza che maggiormente ne influenza il dimensionamento.
Molte compagnie energetiche tedesche sono interessate a migliorare l’efficienza e i costi dei loro impianti eolici e, per questo, incaricano università ed istituti di ricerca (come il Fraunhofer IWES) per indagarne gli aspetti, come ad esempio il comportamento delle fondazioni offshore.
All’autore di questa tesi è stata data l’opportunità di studiare e lavorare al Fraunhofer IWES e perciò questa tesi tratterà del compramento di pali caricati assialmente e staticamente pensati per sottostrutture jacket o tripod per turbine eoliche.
Nello studio effettuato per questa tesi, i dati seprimentali, ottenuti da una campagna sperimentale condotta (in larga scala 1:10 1:5) su pali infissi in terreno sabbioso, sono confrontati attraverso l’impiego delle load-transfer curves (funzioni che descrivono il comportamento d’interfaccia palosuolo) usando sia un’approccio classico (fornito dal metodo di calcolo API Main Text) sia approcci più recenti (dati dai metodi di calcolo CPT).
Uno script Matlab creato appositamente dall’autore di questa tesi riesce ad implementare 11 diversi tipi di load-transfer curves. Il lavoro di tesi si conclude con un esempio pratico in grado di fornire un’idea di come questo script può essere usato nella progettazione.
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Passini, Larissa de Brum. "Instalação e capacidade de carga axial de estacas modelo fluidizadas em solos arenosos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131011.
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O objetivo desta tese foi verificar a viabilidade de utilização de jatos de água verticais circulares, únicos e contínuos, provenientes da ponteira de uma estaca torpedo, para auxiliar sua instalação por peso próprio no leito marinho, através da fluidização do solo. Foram realizados ensaios de laboratório, em modelo reduzido, utilizando hastes para simular estacas torpedo (sem aletas) seguindo a lei de semelhança pelo número de Froude. Os ensaios de instalação por peso próprio, com e sem fluidização, ocorreram sem altura de queda, com a estaca modelo em contato com a superfície do leito. Trabalhou-se com três diâmetros de estacas, seis massas, quatros vazões e areia fina saturada compactada em duas densidades relativas iniciais (média e densa). Os ensaios de arrancamento, em leito arenoso fluidizado e não fluidizado, foram realizados imediatamente, 4, 24 e 48 horas após a instalação dos modelos. A metodologia de instalação proposta mostrou-se viável, quando o jateamento é aplicado desde a superfície em solo arenoso. As profundidades instaladas atingidas por fluidização (L/de > 50) foram consideravelmente superiores às profundidades cravadas por apenas peso próprio (L/de < 5). A geometria da zona perturbada durante a instalação por fluidização dos modelos, permaneceu constante e paralela ao fuste, com geometria de aproximadamente 2de em relação ao modelo, independentemente da vazão aplicada e da densidade relativa inicial do solo. A partir das leis de análise dimensional, uma expressão para a profundidade instalada das estacas modelo foi proposta, mostrando que a mesma é função do peso e da geometria do modelo, das propriedades físicas do solo e do fluido, e de sua vazão. Quanto maior a massa do modelo e a vazão aplicada e menor a densidade relativa, maior a profundidade atingida e maior a velocidade inicial de instalação. Constatou-se que a capacidade de carga axial dos modelos depende da densidade relativa, do diâmetro do modelo e do método de instalação (com e sem fluidização). Independentemente da densidade relativa inicial, o solo fluidizado convergiu para a mesma densidade relativa final, próxima as suas condições no estado crítico. As estacas em solo fluidizado apresentaram ganho resistência com o tempo (efeito de setup), com capacidade de carga inferior às estacas cravadas em solo não fluidizado.The aim of this thesis was to investigate the feasibility of using circular vertical water jets, single and continuous, from the tip of a torpedo pile, to assist its installation by own weight on the seabed, through soil fluidization. Laboratory model tests were carried out, using tubes to simulate torpedo piles (without wings) following the law of similarity defined by the Froude number. The installation tests by the pile own weight, with and without fluidization, occurred without drop height, with the piles in contact with the surface of the bed. Three diameters of model piles and six masses, four flow rates and saturated sand at two initial relative densities (medium and dense) have been used in this set of experiments. Pullout tests in fluidized and nonfluidized soils were performed immediately, 4, 24 and 48 hours after the installation of the models. The proposed installation methodology proved to be feasible when the fluidization is applied from the surface in sandy soils. The installation depths achieved by fluidization (L/de > 50) were significantly higher than the depths reached by pile own weight (L/de < 5). The geometry of the perturbed zone during model installation by fluidization remained constant and parallel to the shaft in a geometry of about 2de of the pile model, regardless of the applied flow rate and the initial relative density of the soil. Following the laws of dimensional analysis, an expression for the embedment of fluidized piles is derived, showing that the penetration depth is a function of pile weight and geometry, fluidized water jet flow rate and velocity, as well as the soil and fluid properties. Increasing the model mass and fluidized flow rate and decreasing the relative density leads to an increase in the depth reached and the initial speed of installation. The axial load capacity of the models depends on the soil relative density, piles diameter and installation method (with and without fluidization). Regardless the initial relative density, the fluidized soil converged to the same final relative density, near its conditions of critical state. Piles installed in fluidized soil presented gain of axial capacity over time (setup effect) with lower resistance than piles driven in nonfluidized soil.
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De, Luca Antonio. "Behavior of Full-Scale Reinforced Concrete Members with External Confinement or Internal Composite Reinforcement under Pure Axial Load." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/348.
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The need to satisfy aerospace industry's demand not met by traditional materials motivated researchers and scientists to look for new solutions. The answer was found in developing new material systems by combining together two or more constituents. Composites, also known as fiber reinforced polymers (FRP) consisting of a reinforcing phase (fibers) embedded into a matrix (polymer), offered several advantages with respect to conventional materials. High specific modulus and strength together with other beneficial properties, corrosion resistance and transparency to electrical and magnetic fields above all, made FRP also suitable for use as construction materials in structural engineering. In the early years of the twenty-first century, the publication by the American Concrete Institute (ACI) of design guidelines for the use of FRP as internal reinforcement and for external strengthening of concrete members accelerated their implementation for structural engineering applications. To date, FRP have gained full acceptance as advanced materials for construction and their use is poised to become as routine as the use of conventional structural materials such as masonry, wood, steel, and concrete. However, new concrete columns internally reinforced with FRP bars and FRP confinement for existing prismatic reinforced concrete (RC) columns have currently important unsolved issues, some of which are addressed in this dissertation defense. The dissertation is articulated on three studies. The first study (Study 1) focuses on RC columns internally reinforced with glass FRP (GFRP) bars; the second (Study 2) on RC prismatic columns externally confined by means of FRP laminates using glass and glass/basalt fibers; and the third (Study 3) is a theoretical attempt to interpret and capture the mechanics of the external FRP confinement of square RC columns. Study 1 describes an experimental campaign on full-scale GFRP RC columns under pure axial load undertaken using specimens with a 24 by 24 in. (0.61 by 0.61 m) square cross section. The study was conducted to investigate whether the compressive behavior of longitudinal GFRP bars impacts the column performance, and to understand the contribution of GFRP ties to the confinement of the concrete core, and to prevent instability of the longitudinal reinforcement. The results showed that the GFRP RC specimens behaved similarly to the steel RC counterpart, while the spacing of the ties strongly influenced the failure mode. Study 2 presents a pilot research that includes laboratory testing of full-scale square and rectangular RC columns externally confined with glass and basalt-glass FRP laminates and subjected to pure axial load. Specimens that are representative of full-scale building columns were designed according to a dated ACI 318 code (i.e., prior to 1970) for gravity loads only. The study was conducted to investigate how the external confinement affects ultimate axial strength and deformation of a prismatic RC column. The results showed that the FRP confinement increases concrete axial strength, but it is more effective in enhancing concrete strain capacity. The discussion of the results includes a comparison with the values obtained using existing constitutive models. Study 3 proposes a new theoretical framework to interpret and capture the physics of the FRP confinement of square RC columns subjected to pure compressive loads. The geometrical, physical and mechanical parameters governing the problem are analyzed and discussed. A single-parameter methodology for predicting the axial stress - axial strain curve for FRP-confined square RC columns is described. Fundamentals, basic assumptions and limitations are discussed. A simple design example is also presented.
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Imbeau, Paul. "Response of Reinforced Concrete Columns Subjected to Impact Loading." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23067.
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Reinforced Concrete (RC) bridge piers, RC columns along exterior of buildings or those located in parking garages are designed to support large compressive axial loads but are vulnerable to transverse out-of-plane loadings, such as those arising from impacts or explosions. To address a lack of understanding regarding blast and impact response of RC members and the need for retrofit techniques to address deficiencies in existing structures, a multi-disciplinary team including various institutes of the National Research Council and the University of Ottawa has initiated work towards developing a fibre reinforced polymer composite protection system for RC columns subjected to extreme shocks. This thesis will focus on the impact program of the aforementioned project. An extensive literature review was conducted to gain a better understanding of: impact loading and associated dynamic effects; experimental testing of RC members subjected to impact; experimental testing of axially loaded members; and retrofit methods for the protection of RC under impact loading. Five half-scale RC columns were constructed and tested using a drop-weight impact machine and two additional specimens were tested under static loading. Deflections, strain distributions within the columns, impact loads and reaction loads were measured during the testing of the built RC members. Comparisons of experimental datum were established between members with differing levels of axial load and between a retrofitted and a non-retrofitted member. Single-degree-of-freedom analysis was used to obtain the predicted response of certain columns under impact loading allowing for comparisons with experimental data.
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Abreu, Celina Wanderley de. "Extensometria : estudo das deformações ao redor de três implantes cone morse, com posicionamento linear, sob carga axial /." São José dos Campos : [s.n.], 2009. http://hdl.handle.net/11449/97354.
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Orientador: Renato Sussumu NishiokaBanca: Renato Sussumu Nishioka
Banca: José Claudio Martins Segalla
Banca: Eduardo Shigueyuki Uemura
Resumo: O objetivo desse estudo foi avaliar a aplicação de carga e distribuição das microdeformações ao redor de implantes com conexão protética cone morse. Três implantes foram inseridos num bloco de poliuretano e pilares microunit foram instalados nos implantes com torque de 20 Ncm. Três coifas usinadas foram adaptadas nos pilares para configurar a supraestrutura protética (n=5) e comparar com as supra-estruturas obtidas com coifas plásticas. Quatro extensômetros foram colados na superfície superior do bloco. Uma carga vertical estática de 30 Kg foi aplicada em cinco pontos das supra-estruturas. Os registros obtidos dos extensômetros foram submetidos ao teste estatístico ANOVA e Tukey (α=5%). As medidas derivadas dessa simulação revelaram que durante a aplicação de carga: (1) existiu uma relação direta do local de aplicação e na distribuição da microdeformação ao redor dos implantes; (2) não existiu diferença na microdeformação entre coifas plásticas e usinadas.
Abstract: The aim of this study was to evaluate the load transfer and strain distribution by an implant-supported fixed partial prosthesis. Three implants Morse Taper were inserted in a polyurethane block and abutments microunit were installed on the implants with a torque of 20 Ncm. Plastic cylinders and prefabricated cylinders were adapted on abutments to fabricate the framework (n=5). Four strain gauges were attached on the superior surface of the block and then each framework was tight on the abutments with a torque of 10 Ncm and vertical load of 30Kg was applied to five points on the framework. The data obtained in the strain gauge analysis were submitted to the statistical tests ANOVA and Tukey (α=5%). The measurements derived from this simulation revealed that: (1) there was a direct proportion between the strain distribution in the metal framework and stresses created in the supporting structure around the implants; (2) there was not a strain difference between plastic and prefabricated cylinders during the load transfer
Mestre
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Samarakkody, Dilrukshie. "Differential axial shortening in high rise buildings with concrete filled tube columns." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/96417/1/Dilrukshie%20Induprabha_Samarakkody%20Arachchilage_Thesis.pdf.
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This research developed and applied a comprehensive technique to evaluate the Differential Axial Shortenings (DASs) in composite high rise buildings. The findings of this research will help to reduce the adverse effects of DASs and facilitate safer designs of buildings. A method, based on the vibration characteristics of the building, to update the initial predictions during the service stage of the building has also been developed and applied.
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Wong, Sze-man, and 黃思敏. "Seismic performance of reinforced concrete wall structures under high axial load with particular application to low-to moderate seismicregions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B34739531.
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Garcia, Jean Rodrigo 1980. "Estudo do comportamento carga VS recalque de estacas raiz carregadas a compressão." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258763.
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Orientador: Paulo Jose Rocha de AlbuquerqueDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Nesta pesquisa analisa-se o comportamento da curva carga vs recalque de estaca isolada carregada à compressão, através do emprego de métodos de previsão. Foram ensaiadas duas estacas raiz, uma com 23m de comprimento e 31cm de diâmetro, e outra com 12m de comprimento e 41cm de diâmetro, no intuito de atribuir o comportamento da interação solo-estaca, a um ou outro fator característico do elemento de fundação. Para isso, foram realizadas provas de carga do tipo lenta. O subsolo local é composto por solo proveniente de diabásio, constituído basicamente de duas camadas, a primeira de argila silto-arenosa (O a 6,5m de profundidade) e a segunda de silte argilo-arenoso (6,5-23m de profundidade), ambas as camadas são predominantes da região de Campinas (SP) e de grande parte das regiões sul e sudeste do Brasil. A prova de carga foi instrumentada de maneira a se obter os dados do mecanismo de transferência de carga e de deslocamento em profundidade. Dessa forma, obteve-se o valor da carga de ruptura, bem como, da respectiva carga admissível (Qadm),através da completa solicitação por atrito lateral e por resistência de ponta, apresentados pela interação do sistema solo-estaca, ou convencionando-se uma ruptura em função de um recalque limite ou ainda de critérios de ruptura fisica, como o método da rigidez (Décourt), Chin e outros. De maneira geral, analisa-se, de maneira critica, os métodos de previsão de recalque e de curva carga vs recalque, comparando os resultados reais com os previstos, através dos métodos teóricos e empíricos para o recalque do elemento fundação quando submetido à carga admissível estimada (Qadm)e para a curva carga vs recalque. Dessa forma, pretende-se chegar a algum entendimento sobre a interação solo-estrutura e seu modelo de transferência de carga para o solo
Abstract: In this research, the behavior of the curve load versus settlement ofloaded isolated pile to the compression is analyzed, through forecast methods. Two root piles had been assayed, one with 23m oflength and 31 cm of diameter, and the other with length of 12 m and 41 cm of diameter, in order to attribute the behavior of the interaction ground-pile to one or another characteristic factor of the foundation elemento For this, load tests of the slow type had been carrried out. The local subsoil is composed of ground of diabásio, consisting basically of two layers: the first one of silt-sandy clay (6,5m - 23m of depth) and second silt clay-sandy (6,5 - 23m of depth), both layers are predominant in the region ofCampinas (SP) and in a great part ofthe southem and southeastem regions ofBrazil. The load test was instrumented to get the data of the mechanism of transference of load and displacement in depth. Thus, the value of the rupture load was obtained, as well as the respective permissible load (Qadm),through the complete request for lateral attrition and tip resistance, presented by the interaction of the ground-pile system or stipulating a rupture related to a stress limit or still of criteria of physical rupture, as the method of the rigidity (Décourt), Chin and others. In general, the methods of forecast of settlement and curve load versus stresses are analysed in a critical way, by comparing the real results with the foreseen ones, through theoretical by empirical methods for the settlement of the foundation element when. submitted to the esteemed permissible load (Qadm) and for the curve load versus settlement. Therefore, there is the intention to come to an agreement about the groundstructure interaction and its model of load transference to the ground
Mestrado
Geotecnia
Mestre em Engenharia Civil
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McFall, Bruce Daniel. "The Effects of Multi-Axial Loading on Adhesive Joints." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515074800550415.
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Allington, Christopher James. "Seismic Performance of Moment Resisting Frame Members Produced from Lightweight Aggregate Concrete." Thesis, University of Canterbury. Civil Engineering, 2003. http://hdl.handle.net/10092/1254.
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A total of 47 lightweight aggregate concrete columns were constructed from four different types of lightweight aggregate and provided with different quantities of transverse reinforcement. The specimens were tested under a monotonically increasing level of compressive axial load. The rate of load application was varied from pseudo-static to the rate of dynamic loading expected during a major seismic excitation. The results from the experimental testing of the column members were used to derive a theoretical stress-strain model to predict the behaviour of lightweight aggregate concrete members under imposed loads. The stress-strain model was derived to predict the response of both lightweight aggregate and conventional weight concretes with compressive strengths up to and including 100 MPa. The model was calibrate against the experimental results obtained in this study and previously tested lightweight aggregate and conventional weight concrete columns. A series of pseudo-cyclic moment-curvature analyse were undertaking using the derived stress-strain model, to predict the behaviour of the lightweight aggregate concrete members when subjected to axial load and flexure. The results were compared to the confinement requirements in the potential plastic hinge regions of column elements required by the New Zealand Concrete Structures Standard, NZS3101: 1995. It was determined that the confinement requirements of NZS3101: 1995 were could be used to accurately determine the required quantity of transverse reinforcement for lightweight aggregate concrete members with a concrete density greater than 1700 kg/m3. A total of four lightweight aggregate concrete beam column subassemblies were constructed and tested under reversed cyclic lateral loading. The results from the specimen indicate that cyclic behaviour of the lightweight aggregate concrete was similar to conventional weight concrete. However the bond capacity between the longitudinal reinforcement and the surrounding concrete was weaker than previously tested conventional weight concrete members.