Dissertations / Theses on the topic 'Axial loads'
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1
Knappett, Jonathan Adam. "Piled foundations in liquefiable soils : accounting for axial loads." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595853.
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Lund, Julie. "Buckling of cylindrical members with respect to axial loads." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produktutvikling og materialer, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26324.
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Managing technology and taking advantage of the opportunities to further development is essential to ensure increased hydrocarbon recovery and barrier security for upstream energy companies. Interwell is a well intervention company operating globally, with main competence in plug and straddle solutions with related setting, pulling and measurement tools. In many of Interwell’s product lines, cylindrical members and pipes are being exposed to axial compressive loads in both static and dynamic conditions. The purpose of this study was to increase the knowledge on how to facilitate full utilization of the limited design space available for Down Hole Equipment by minimizing the gap between the numerical and the experimental results and to find global safety factors. This study introduces options to supplement the safe design of axially loaded members, focusing mainly on the Setting Chamber Mandrel, a cylindrical member in the Hydrostatic Setting Unit. The Setting Chamber mandrel has to resist compression caused by increasing well pressure while running in hole. The prominence of the failure mode depends on several factors including member slenderness, section slenderness, strength, influence of connections and restrains, geometric imperfections and residual stresses.The members in this study have been characterized into three general types depending on their proneness to buckling; short, intermediate and long. The dividing lines between short, intermediate and long members shall not be considered as accurately defined; furthermore the maximum load-carrying capacity of a member in each category is based upon different types of mechanical failure scenarios. The Setting Chamber Mandrel is classified as intermediate and will fail by both yielding and buckling; i.e. inelastic buckling behavior. Failure of intermediate members could be progressive and unpredictable, and it is common practice to use large safety factors when predicting the buckling strength. A safe design approach has been suggested for predicting the critical load and critical stresses of intermediate members by comparing experimental results to existing literature.The experimental study consists of three experimental tests; TEST 1: length and diameter, TEST 2: temperature and TEST 3: well pressure. The results obtained from the experimental study were compared with NS-EN 1993-1-1:2005, FE-analyses and established linear buckling theory; Euler and J.B. Johnsons equations. Linear elastic eigenvalue buckling analysis and nonlinear static buckling analyses were performed with finite element software package Abaqus 6.12. In order to understand the buckling behavior of the Setting Chamber Mandrel elastic-plastic material properties was added to the nonlinear large deformation buckling analysis. The results from the analyses were used as a pre-study for the experimental testing and for post-buckling analysis to validate the results to establish the reliability and uncertainties of the numerical methods. Results indicate that NS-EN 1993-1-1:2005 and the nonlinear analysis techniques are suitable to accurately predict the critical buckling load of an axially loaded compression member. The results from the nonlinear static large deformation buckling analysis using elastic-plastic material properties show most agreement with the experimental studies.The partial safety factors in the global safety factor presented in this study are utilized based on anticipated conditions to ensure that build in functionality and constructional integrity of the Setting Chamber Mandrel will not affect the overall integrity of the Hydrostatic Setting Unit. The appropriate global safety factor for intermediate members with similar shape and boundary conditions as the Setting Chamber Mandrel is concluded to be 1.5 when calculating buckling strength with Interwell’s safe design procedure. In order to obtain a high degree of confidence in the design of axially loaded compression members it is recommended to follow the complete methodology provided in this study.
3
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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Rupp, John F. "MODELING OF STEEL-JACKETED REINFORCED CONCRETE UNDER AXIAL COMPRESSIVE LOADS." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330615432.
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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.
6
Yun, Xiaoyou 1965. "Geomechanical behaviour of biaxially loaded rock." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115913.
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The stress state at the boundary of any underground mine opening is that of plane stress. This planar state of stress can be simulated in laboratory by subjecting a cubic rock specimen to a biaxial loading condition. Thus, research on the behaviour of biaxially loaded rock is important for better understanding of the stability of mining fronts such as crown pillar skin, drift face or shaft floor.The objective of this research is to study the geomechanical behaviour of biaxially loaded rock. Three rock types were selected, namely limestone, granite and sandstone.
The laboratory work was conducted using a newly developed, 500-tonne biaxial loading frame, that is equipped with a servo-controlled load and displacement system. Recently patented in China, the new biaxial loading frame is spatially symmetric and equally rigid in both directions. Steel brush platens and solid platens with and without MoS2 were developed to help examine the end friction effect on biaxial strength. It is found that the biaxial strength can decrease up to 26.7% with the increase of cubic specimen size from 75 mm to 150 mm. The biaxial strength increases by 29.3% with the increase of loading rate from 1 MPa/s to 10 MPa/s, for granite. The biaxial strength of granite specimen decreases by nearly 6% when either solid platens with MoS 2 lubricant or brush platens are used. A comparison of the sigma 1-sigma2 failure envelopes reveals that the shape of the envelope and the location of the peak biaxial strength are dependent on the rock type.
Varying intensities of rock spalling generally initiate at the free faces of the specimen when sigma1 and sigma2 exceed sigma c/2. Ultimate failure occurs in the form of an out-of-plane shear failure, which splits the rock specimen into two or more wedges.
It is shown that both Mohr-Coulomb and Hoek-Brown criteria underestimate the biaxial strength of the rock. The Drucker-Prager failure criterion appears to provide poor correlation with experimental results. A new empirical biaxial rock failure criterion for intact rock is derived and another, accounting for rock mass characteristics through the Geological Strength Index (GSI), is then proposed.
7
Alday, John Hane. "The correlation of randomness with high tip losses in an axial flow fan stage." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-11242009-020017/.
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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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熊朝暉 and Zhaohui Xiong. "Reinforced concrete column behavior under cyclic loading." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31243836.
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Xiong, Zhaohui. "Reinforced concrete column behavior under cyclic loading /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23530121.
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Lee, Chung-Sheng. "Modeling of FRP-jacketed RC columns subject to combined axial and lateral loads." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3211782.
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Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed June 14, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 288-295).
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Fan, Jinsong. "Modeling of Lightly Confined Reinforced Concrete Columns Subjected to Lateral and Axial Loads." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515132459608892.
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Yang, Yu-Wen. "Behavior of three-span braced columns with equal and unequal spans." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07292009-090428/.
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Yucel, Mustafa Can. "Structural Identification, Damage Detection By Non-destructive Tests And Determining Axial Loads In Cables." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611278/index.pdf.
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Damage and condition identifi
cation of existing structures using non-destructive tests is a common challenge that has been worked on for a long time. In this study, two di&
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erent methods were developed to &
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nd existing force on cables as well as determine bending characteristics (EI coe&
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cients) of beam like structures (such as bridges). Comparing forces in symmetrically placed cables or against values obtained from design drawings would indicate structural imbalance as well as &
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nding EI coe&
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cients at a number of segments on a bridge girder might indicate weak regions that might possibly have undergone structural damage, having weak connections, lost composite action etc. With the help of the proposed algorithm, the sti&
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ness parameters of bridges can be assessed and the location of any damage that is in the magnitude which can a&
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ect displacement behavior of system can be located. The developed methods are demonstrated using the values analytically obtained from the created models and the e&
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ectiveness of the algorithm is criticized. Furthermore, several damage scenarios on a scaled lab beam was used to test the application using real experimental data
including tests on undamaged beam (for identi&
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cation) and tests on the damaged beam. Additional experiments were conducted on a cable stretched in the laboratory instrumented using a load cell to measure instantaneous axial load on the cable and compare these values against the values obtained from the developed tension measurement device. The results are compared and conclusions are derived.
15
Tsantrizos, Anthony. "Internal deformation and strain of human lumbar intervertebral discs subjected to multi-axial loads." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86056.
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Morphological and clinical signs of lumbar intervertebral disc disruption are pronounced in the posterior and postero-lateral inner annulus fibrosus. The regional intervertebral disc predisposition to disruption suggests that intradiscal stresses and strains may also be region specific and possibly initiate the disruption. Quantitative data describing intradiscal deformations have been limited to the mid-sagittal plane using techniques that compromise the intervertebral disc integrity. No experimental study has quantified intradiscal strain patterns. The initial objectives of the present work were to use experimental cadaveric methods and finite element techniques to develop and validate methods of measuring intradiscal deformations and strains along the complete mid-transversal plane using a fine wire grid.Subsequently, these methods were used to quantify intradiscal deformations and strains in healthy and degenerated intervertebral discs during sub-maximal loads. Eighteen healthy and degenerated intervertebral discs were subjected with wires placed within and beads glued along their mid-traversal plane surface, to compression, extension, flexion and lateral bending. Cramo-caudal radiographs at unloaded and loaded steps documented wire and bead positions. Intradiscal nucleus pulposus displacements, circumferential, radial and shear strains in the annulus fibrosus and transitional zone under load were compared among all anatomical regions and between healthy and degenerated intervertebral discs.
The methods develop to estimate intradiscal strains from intradiscal wire intersection displacements demonstrated a relative overall accuracy of 2.9% (i.e. percent error from theoretical estimations). Generally, intradiscal circumferential and radial strains decreased from the transitional zone to the annulus fibrosus and increased at the side of bending during all bending conditions. Circumferential and radial strain peaks were observed in the postero-lateral regions even in healthy intervertebral discs during extension and lateral bending. Shear strains were generally uniform within the healthy intervertebral disc. Degeneration significantly increased intradiscal circumferential, radial and shear strains during all bending conditions (particularly in the postero-lateral regions). The increased nucleus pulposus migration in degenerative intervertebral discs appeared to have caused the increases in circumferential and radial strains and to some extent perhaps increases in shears strains.
The inner postero-lateral annulus fibrosus is predisposed to excessive normal circumferential and radial strains early on which coincide with morphological changes observed in the same regions. This observation suggests a predisposition to failure likely due to an inability of resisting delaminating normal strains. Furthermore, the increased nucleus pulposus migration observed in degenerated intervertebral discs appears to shift the pivot point during bending movements more posterior, which consequently forces the postero-lateral regions to consistently experience higher circumferential and radial strains. These effects may contribute to the segmental instability observed in degenerated motion segments prior to intervertebral disc failure.
16
Bulusu, Prashant. "Rolling contact fatigue predictions based on elastic-plastic finite element stress analysis and multiaxial fatigue /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1437664.
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Thesis (M.S.)--University of Nevada, Reno, 2006."August, 2006." Includes bibliographical references (leaves 38-45). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
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Willis, C. R. "Design of unreinforced masonry walls for out-of-plane loading /." Title page, abstract and table of contents only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phw7342.pdf.
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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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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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Rocca, Silvia. "Experimental and analytical evaluation of FRP-confined large size reinforced concrete columns." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Rocca_09007dcc803bfaf5.pdf.
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Thesis (Ph. D.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 12, 2008) Includes bibliographical references.
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Wolfe, David R. "Delamination buckling, postbuckling, and growth in axially loaded beam-plates." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/80114.
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The purpose of this study is to develop a simple one-dimensional model to analyze axially loaded beam-plates containing cracks which extend through the thickness of the beam-plates. Although the material analyzed is isotropic, these cracks will be referred to as delaminations. Buckling, postbuckling, and growth of delaminations in these beam-plates will be analyzed. A finite element method in which all of the terms of the stiffness matrices are obtained by exact integration is employed to determine the linear buckling load and postbuckling solution. The energy release rate is then determined using the postbuckling solution. Curves are provided to show the effect of delamination length and location on buckling loads, energy release rates, and strengths of the beam-plates. The problem of buckling and postbuckling of beams with multiple delaminations is also considered. A method of calculating the energy release rate for beams with multiple delaminations using numerical differentiation is introduced.Master of Science
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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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Hussein, Amgad Ahmed. "Behaviour of high-strength concrete under biaxial loading conditions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0008/MQ34188.pdf.
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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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Xu, Xiangtao. "Investigation of the end bearing performance of displacement piles in sand." University of Western Australia. School of Civil and Resource Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0086.
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[Truncated abstract] The axial performance of piles in sand remains an area of great uncertainty in geotechnical engineering. Over the years, database studies have shown that the existing method for offshore piles (e.g. API 2000) is unreliable. There is therefore a clear need for an improved predictive method, which incorporates the state-ofthe- art understanding of the underlying controlling mechanisms. This Thesis is dedicated to address the factors influencing the end bearing performance of displacement piles in siliceous sand with a view to proposing and justifying an improved design formulation. Firstly, a database of displacement pile load tests in sand with CPT data was compiled in collaboration with James Schneider (Schneider 2007). It features the widest database with also the latest available pile load test data (e.g. Euripides, Ras Tanajib, Drammen etc) in electronic form. Evaluation of the three new CPTbased methods (Fugro-05, ICP-05 & NGI-05) against this database has revealed a broadly similar predictive performance despite their end bearing formulations being remarkably different. This anomaly promoted the author to extend the database to include additional tests with base capacity measurements to form new base capacity databases for driven and jacked piles, which resulted in the UWA- 05 method for end bearing of displacement piles in sand. This method accounts for the pile effective area ratio, differentiates between driven and jacked piles, and employs a rational qc averaging technique. ... Field tests were performed in Shenton Park, Perth to supplement the database study and, in particular, to examine the effect of the incremental filling ratio (IFR). 10 open-ended and 2 closed-ended piles were tested in compression followed by tension. The test results provide strong support for the UWA-05 method for base capacity evaluation employing the CPT qc values and the effective area ratio. A series of jacked pile tests was carried out on the UWA beam centrifuge, to further explore the factors affecting pile base response. In total, four uniform and four layered centrifuge samples were prepared and tested at various stress levels and relative densities using three separate pile diameters. The resistance ratio (qb0.1/qc,avg) is found to be independent of the absolute pile diameter, effective stress and soil relative density. The tests in layered soil enabled quantification of the reduction in penetration resistance when a pile/cone approaches a weak layer and revealed the significant influence on base stiffness of underlying soft clay layers. The stiffness decay curves (G/GIN vs. w/D, where GIN is initial operational shear stiffness) measured in static load tests were found to vary with ratios of GIN/qc, while there was a unique relationship between G/GIN and qb/qc. A detailed parametric study was carried out (using the FE code PLAXIS) by idealising pile penetration using a spherical cavity expansion analogue in layered soil. The numerical predictions compare well with the centrifuge results and their generalization enabled guidelines to be established for end bearing in layered soil.
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Levy, Nina Hannah. "Modelling multi-directional behaviour of piles using energy principles." University of Western Australia. Dept. of Civil and Resource Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0211.
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The loads applied to pile foundations installed offshore vary greatly from those encountered onshore, with more substantial lateral and torsional loads. For combined axial and lateral loading the current design practice involves applying an axial load to a deep foundation and assessing the pile behaviour and then considering a lateral load separately. For the problem of an altering directions of lateral loads (e.g. due to changes in the wind directions acting on offshore wind turbines) a clear design procedure is not available. There is thus a need for a clearly established methodology to effectively introduce the interaction between the four different loading directions (two lateral, one axial and one torsional). In this thesis, a model is presented that introduces a series of Winkler elasto-plastic elements coupled between the different directions via local interaction yield surfaces along the pile. The energy based method that is used allows the soil-pile system to be defined explicitly using two equations: the energy potential and the dissipation potential. One of the most interesting applications of this model is to piles subjected to a change in lateral loading direction, where the loading history can significantly influence the pile behaviour. This effect was verified by a series of experimental tests, undertaken using the Geotechnical Centrifuge at UWA. The same theory was then applied to cyclic loading in two dimensions, leading to some very useful conclusions regarding shakedown behaviour. A theoretically based relationship was applied to the local yielding behaviour for a pile subjected to a combination of lateral and axial loading, allowing predictions to be made of the influence of load inclination on the pile behaviour. The ability of this model to represent interaction between four degrees of freedom allows a more realistic approach to be taken to this problem than that considered in current design practice.
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Vedera, Kevin G. "An Experimental Methodology for Evaluating Power Losses of Rolling Element Bearings Subjected to Combined Radial and Axial Loads." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1522933829712819.
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Chen, Wen. "Uniaxial behaviour of suction caissons in soft deposits in deepwater." University of Western Australia. School of Civil and Resource Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0136.
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Suction caissons are a cost-effective alternative to traditional piles in deep to ultradeep waters. No design rule has been available on the axial capacity of suction caissons as part of the mooring system in soft sediments. In this research, a series of centrifuge tests were performed using instrumented model caissons, to investigate the axial capacity and radial stress changes around caissons during installation, consolidation and vertical pullout in normally consolidated, lightly overconsolidated and sensitive clays. Total pressure transducers instrumented on the caisson wall were calibrated for various conditions. The radial total stress acting on the external wall varied almost linearly during penetration and extraction of the caisson, with smaller gradients observed during post-consolidation pullout. Minimum difference was found in the penetration resistance and the radial total stress for caissons installed by jacking or by suction, suggesting that the mode of soil flow at the caisson tip is similar under these two types of installation. Observed soil heave showed that the soil particles at the caisson tip flow about evenly outside and inside the caisson during suction installation. Comparison was made between measurements and various theoretical predictions, on both the radial stress changes during caisson installation, and the radial effective stress after consolidation. Significant under-predictions on excess pore pressure changes, consolidation times and external shaft friction ratios were found for the NGI Method, based on the assumption that the caisson wall is accommodated entirely by inward motion of the clay during suction installation. Obvious over-predictions by the MTD approach were found in both stress changes and shaft capacity of the caissons. A simple form of cavity expansion method was found to give reasonable estimations of stress changes and post-consolidation external shaft friction. A model for predicting the penetration resistance of suction caissons in clay was evaluated. Upper and lower bound values of external shaft friction ratio during uplift loading after consolidation were derived. Uplift capacity of caissons under sustained loading and cyclic loading were investigated, revealing approximately 15 to 30% reduction of the capacity compared to that under monotonic loading. External shaft friction ratios and reverse end-bearing capacity factors were both found to be significantly lower than those under monotonic loading
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Garner, Michael Paul. "Loading Rate Effects on Axial Pile Capacity in Clays." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2016.pdf.
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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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Erdil, Baris. "Behavior Of Cfrp Confined Concrete Specimens Under Temperature Cycles And Sustained Loads." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614137/index.pdf.
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The application of carbon fiber reinforced polymers (CFRP) is one of the effective retrofitting and strengthening methods that is used worldwide and is starting to be used in Turkey as well because they have high strength and high modulus in the fiber direction, have very low coefficient of thermal expansion when compared to concrete and steel and are known not to corrode. Since FRPs are lightweight, their mass can be neglected when compared to concrete and steel.
However, before proposing this material as an alternative for strengthening and retrofitting applications their long-term behavior should be understood because they are applied on to concrete by several layers of epoxy-based adhesives, which can be affected by change in humidity, temperature and load. Therefore, behavior of CFRP-strengthened structures in varying temperature and humidity conditions must be investigated.
In this dissertation, behavior of CFRP confined cylindrical and prismatic concrete specimens having square cross-section were investigated under sustained compressive loads, dry and wet heating-cooling cycles, and outdoor exposures under direct sunlight, to determine the possible changes in their mechanical properties. Sustained loads were applied as the 40% and 50% of their confined axial load capacity. In addition to the sustained loads, specimens were subjected to 200 heating-cooling cycles between -10°C to 50°
C. In order to understand the change in behavior of CFRP confined concrete specimens better, they were divided in six groups. A single effect was investigated in each group. After aging tests mechanical properties of the specimens were recorded via monotonic uniaxial loading. It was observed that temperature cycles had little effect on behavior but sustained loads changed the shape of the axial stress-strain diagram and resulted in a dramatic decrease in ultimate strain. Based on the test results and also using the data of similar studies available in the literature, strength and strain models considering the exposures as independent parameters were established and finally axial stress-strain curve was tried to be predicted.
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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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Aules, Wisam Amer. "Behavior of Non-Ductile Slender Reinforced Concrete Columns Retrofit by CFRP Under Cyclic Loading." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4804.
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In the Middle East region and many countries in the world, older reinforced concrete (RC) columns are deemed to be weak in seismic resistance because of their low amount of reinforcement, low grades of concrete, and large spacing between the transverse reinforcement. The capacity of older RC columns that are also slender is further reduced due to the secondary moments. Appropriate retrofit techniques can improve the capacity and behavior of concrete members. In this study, externally bonded Carbon Fiber Reinforced Polymer (CFRP) retrofit technique was implemented to improve the behavior of RC columns tested under constant axial load and cyclic lateral load. The study included physical testing of five half-scale slender RC columns, with shear span to depth ratio of 7. Three specimens represented columns in a 2-story, and two specimens represented columns in a 4-story building. All specimens had identical cross sections, reinforcement detail, and concrete strength. Two specimens were control, two specimens were retrofit with CFRP in the lateral direction, and one specimen retrofit in the longitudinal and lateral directions. A computer model was created to predict the lateral load-displacement relations. The experimental results show improvement in the retrofit specimens in strength, ductility, and energy dissipation. The effect of retrofitting technique applied to two full-scale prototype RC buildings, a 2-story and a 4-story building located in two cities in Iraq, Baghdad, and Erbil, was determined using SAP2000.
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Fridh, Jens. "Experimental Investigation of Performance, Flow Interactions and Rotor Forcing in Axial Partial Admission Turbines." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-53699.
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The thesis comprises a collection of four papers with preceding summary and supplementary appendices. The core investigation solely is of experimental nature although reference and comparisons with numerical models will be addressed. The first admission stage in an industrial steam turbine is referred to as the control stage if partial admission is applied. In order to achieve high part load efficiency and a high control stage output it is routinely applied in industrial steam turbines used in combined heat and power plants which frequently operate at part load. The inlet flow is individually throttled into separate annular arcs leading to the first stator row. Furthermore, partial admission is sometimes used in small-scale turbine stages to avoid short vanes/blades in order to reduce the impact from the tip leakage and endwall losses. There are three main aspects regarding partial admission turbines that need to be addressed. Firstly, there are specific aerodynamic losses: pumping-, emptying- and filling losses attributed to the partial admission stage. Secondly, if it is a multistage turbine, the downstream stages experience non-periodic flow around the periphery and circumferential pressure gradients and flow angle variations that produce additional mixing losses. Thirdly, the aeromechanical condition is different compared to full admission turbines and the forcing on downstream components is also circumferentially non-periodic with transient load changes. Although general explanations for partial admission losses exist in open literature, details and loss mechanisms have not been addressed in the same extent as for other sources of losses in full admission turbines. Generally applicable loss correlations are still lacking. High cycle fatigue due to unforeseen excitation frequencies or due to under estimated force magnitudes, or a combination of both causes control stage breakdowns. The main objectives of this thesis are to experimentally explore and determine performance and losses for a wide range of partial admission configurations. And, to perform a forced response analysis from experimental data for the axial test turbine presented herein in order to establish the forced response environment and identify particularities important for the design of control stages. Performance measurements concerning the efficiency trends and principal circumferential and axial pressure distortions demonstrate the applicability of the partial admission setup employed in the test turbine. Findings reveal that the reaction degree around the circumference varies considerably and large flow angle deviations downstream of the first rotor are present, not only in conjunction to the sector ends but stretching far into the admission sector. Furthermore, it is found that the flow capacity coefficient increases with reduced admission degree and the filling process locally generates large rotor incidence variation associated with high loss. Moreover, the off design conditions and efficiency deficit of downstream stages are evaluated and shown to be important when considering the overall turbine efficiency. By going from one to two arcs at 52.4% admission nearly a 10% reduction in the second stage partial admission loss, at design operating point was deduced from measurements. Ensemble averaged results from rotating unsteady pressure measurements indicate roughly a doubling of the normalized relative dynamic pressure at rotor emptying compared to an undisturbed part of the admission jet for 76.2% admission. Forced response analysis reveals that a large number of low engine order force impulses are added or highly amplified due to partial admission because of the blockage, pumping, loading and unloading processes. For the test turbine investigated herein it is entirely a combination of number of rotor blades and low engine order excitations that cause forced response vibrations. One possible design approach in order to change the force spectrum is to alter the relationship between admitted and non-admitted arc lengths.Denna sammanläggningsavhandling består av fyra artiklar och föregås av en sammanfattning med kompletterande bilagor. Kärnan av undersökningen är experimentell även om referenser och jämförelser med numeriska modeller förekommer där så bedöms lämpligt. Det första steget i en industriell ångturbin kallas reglersteg om partialpådrag tillämpas. Det används rutinmässigt i kraftvärmeanläggningar som ofta körs vid dellaster för att åstadkomma en hög dellastverkningsgrad och hög stegeffekt. Inloppsflödet delas in separata och individuellt strypreglerade pådragsbågar som leder till det första munstycksgittret. Ibland används partialpådrag i små turbiner för att undvika korta blad och på så sätt minska takläckage och ändväggsförlusternas inflytande på den totala förlusten. Det finns i huvudsak tre aerodynamiska/aeromekaniska egenheter som bör beaktas. Först det första är det speciella aerodynamiska förluster associerade till partialpådrag eller reglersteget: ventilations-, tömnings och fyllningsförluster. För det andra, om det är en flerstegsturbin påverkas också nedströms steg negativt av det asymmetriska flödet runt omkretsen som innefattar stora tryckvariationer och flödesvinkelvariationer. För det tredje är den aeromekaniska situationen speciell jämfört med ett fullpådraget steg. För partialpådrag existerar dynamiska krafter med snabba laständringar vid in och utpassering i pådragsbågen. Även om det existerar generella förklaringar i den öppna litteraturen angående förluster så har inte förlustmekanismerna utretts i samma omfattning jämfört med fullpådrag. Ingen generell förlustkorrelation finns. Utmattning på grund oförutsedda excitationsfrekvenser, underskattade kraftamplituder eller en kombination av båda orsakar reglerstegshaveri för ångturbinintressenter. De huvudsakliga målsättningarna med denna studie är att experimentellt utforska och bestämma prestanda och förluster för ett stort antal partialpådragskonfigurationer. Samt att genomföra en vibrationsanalys (relaterat till aerodynamiska kraftimpulser) utifrån mätdata från provturbinen avhandlad häri. Detta för att kartlägga de aeromekaniska förutsättningarna och om möjligt identifiera egenheter viktiga för konstruktion av reglersteg. Prestandamätningar rörande verkningsgradstrender och generella strömningsvariationer runt omkretsen bekräftar resultat från den öppna litteraturen och därmed demonstrerar dugligheten av den partialpådragskonfiguration som används i luftprovturbinen. Dessutom visar resultaten bland annat att reaktionsgraden varierar kraftigt runt omkretsen med stora variationer i rotorns utloppsvinkel inte enbart i anslutning till sektorändar utan långt in i pådragssektorn. Flödeskapacitetskoefficienten eller turbinkonstanten ökar med minskat pådrag och fyllningsprocessen genererar stora variationer i rotorns inloppsvinkel förknippade med höga förluster. Det är viktigt att beakta dellastförutsättningarna och verkningsgradsminskningen för nedströms steg. Genom att använda två pådragsbågar istället för en för ett givet pådrag av 52,4% minskar partialpådragsförlusterna för nedströmssteget med nästan 10 % vid designpunkten, härlett från mätningar. Samlade medelvärden från roterande instationära mätningar visar på en fördubbling av det relativa dynamiska trycket vid rotortömning jämfört med en opåverkad del av pådragsbågen. Vibrationsanalys (relaterat till aerodynamiska kraftimpulser) av mätdata avslöjar att partialpådrag orsakar en stor mängd kraftimpulser med låga varvtalsmultiplar, främst från ventilationen och påavlastningsprocesserna. För provturbinen så är det helt och hållet kombinationer mellan antalet rotorblad och dessa kraftimpulser som orsakar strömningspåverkade vibrationer. Ett möjligt tillvägagångssätt konstruktionsmässigt för att ändra kraftspektrumet är att ändra längförhållandet mellan pådragen och blockerad del.
QC 20120109
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Schäffner, Maximilian Frederic [Verfasser], Tobias [Akademischer Betreuer] Melz, and Uwe [Akademischer Betreuer] Klingauf. "Quantification and evaluation of uncertainty in active buckling control of a beam-column subject to dynamic axial loads / Maximilian Frederic Schäffner ; Tobias Melz, Uwe Klingauf." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1186258616/34.
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Hoffmann, Daniel E. "Ex Vivo Biomechanical Evaluation of the Canine Cranial Cruciate Ligament Deficient Stifle with Varying Angles of Stifle Joint Flexion and Axial Loads After Tibial Tuberosity Advancement." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243981690.
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Salim, Md Wadud. "Deformation and degradation aspects of ballast and constitutive modelling under cyclic loading." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050215.114659/index.html.
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Carvalho, Jessica Pires de. "Avaliação da estabilidade inicial de implantes instalados em modelos ósseos suínos padronizados em posicionamentos ao nível ou infraósseos." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/58/58132/tde-26092016-145807/.
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A estabilidade primária é decorrente da adaptação mecânica imediata entre o osso e o implante após a sua inserção. O sucesso desta adaptação depende de fatores como a densidade e qualidade ósseas, tamanho, diâmetro, forma e rugosidade da superfície do implante. As cargas oclusais aplicadas sobre o implante podem afetar o osso circundante. Esse estudo teve como objetivo avaliar, comparativamente, a estabilidade inicial de implantes ósseo inseridos em cilindros de osso suíno padronizados, em diferentes posicionamentos ósseos, com e sem a aplicação de carga, por meio de análises de imagens tridimensionais (microtomografia computadorizada) e análises mecânicas (Frequência de ressonância, Torque de inserção e Ensaio de arrancamento). Os cilindros ósseos foram preparados a partir de osso suíno e separados em 2 grupos conforme a área doadora: Grupo A: cilindros removidos da cabeça do fêmur (alta densidade óssea) e Grupo B: cilindros removidos do côndilo mandibular (baixa densidade óssea). Previamente aos procedimentos experimentais, os cilindros ósseos foram certificados através de análises de imagens 2D (radiografia digital), para garantir a uniformidade intra-grupos e distinção entre os grupos dos espécimes. Após a certificação, foram feitas microtomografias computadorizadas dos cilindros ósseos para análise tridimensional de imagens prévia à instalação dos implantes, avaliando os seguintes parâmetros: porcentagem de volume ósseo (BV/TV), separação trabecular (TbSp), razão entre a medida da área superficial do osso e o seu volume ósseo (BS/BV) e porcentagem de porosidade total (POTOT). Depois disso, foram selecionados 60 implantes, que foram divididos em 4 grupos, cada um com 15 implantes: G1 (cilindros ósseos de alta densidade com implante situados ao nível ósseo), G2 (cilindros ósseos de alta densidade com implante 2 mm infraósseo), G3 (cilindros ósseos de baixa densidade com implante ao nível ósseo) e G4 (cilindros de baixa densidade com implante 2 mm infraósseo). A instalação dos implantes seguiu o protocolo recomendado pelo fabricante e durante o procedimento foi realizada a medida do torque de inserção. Após a instalação dos implantes, os cilindros ósseos foram submetidos à nova análise tridimensional (com avaliação dos mesmos parâmetros anteriores, nas áreas intra-roscas e adjacente à estas, acrescidos da medida da área de contato ossoimplante (BIC). Foi então realizada a avaliação do Coeficiente de Estabilidade (ISQ), utilizando a análise de frequência de ressonância (Osstell®). Após essa avaliação, 5 implantes de cada grupo foram submetidos ao ensaio de arrancamento. Os 10 implantes de cada grupo restantes foram conectados a pilares protéticos adequados, os quais receberam uma aplicação de forças axial (G1, G2, G3 e G4, 5 implantes de cada grupo) e lateral (G1, G2, G3 e G4, 5 implantes de cada grupo). Após aplicação das forças, os cilindros ósseos foram submetidos a nova análise tridimensional com avaliação dos mesmos parâmetros descritos, a nova análise de frequência de ressonância e ao ensaio de arrancamento. As variáveis foram testadas em relação à normalidade dos dados. Para todas as análises foi considerado um nível de significância de 5%. As análises estatísticas foram realizadas com base nos dados absolutos obtidos durante a análise tridimensional em cada situação de carga (antes do implante, pósimplante e pós-carga) e com a variação entre os valores das situações pós-implante e póscarga (variação carga - implante). A avaliação estatística do parâmetro de análise de frequência de ressonância não encontrou diferenças estatisticamente significantes para as comparações entre grupos G1 versus G3 e G2 versus G4 nas avaliações pós implante e pós carga. Em relação ao torque de inserção, houve diferenças estatisticamente significantes para as comparações entre grupos com implantes instalados no mesmo nível G1 versus G3 e G2 versus G4. Os maiores valores de torque de inserção obtidos foram registrados nos grupos de alta densidade. A análise estatística do ensaio de arrancamento mostrou diferenças estatisticamente significantes para as comparações: G1 versus G3 (inicial) e G1 versus G4 (inicial). Após a aplicação de carga oclusal, pode-se constatar diferenças estatisticamente significantes para as comparações: G1 versus G3 e G2 versus G4, após aplicação de carga lateral a análise mostrou diferença estatisticamente significante para a comparação G3 versus G4. Os resultados das análises tridimensionais mostraram diferenças estatisticamente significantes para os parâmetros TbSp e POTOT na avaliação da área óssea intra-rosca. A avaliação dos dados de variação após a aplicação de carga oclusal e lateral para o parâmetro TbSp, mostrou diferenças estatisticamente significantes para as comparações G2 versus G4. Em relação ao parâmetro POTOT, a aplicação de carga oclusal e lateral mostrou diferença estatisticamente significante para as análises: G1 versus G2 e G2 versus G4. Em relação ao parâmetro BSBV a análise dos valores absolutos, mostrou diferenças estatisticamente significantes para a área óssea intra-rosca dos grupos de baixa densidade. Já a análise dos valores de variação, a aplicação de carga oclusal mostrou diferenças estatisticamente significantes para os grupos G1 versus G3, G2 versus G4 e G3 versus G4, enquanto a aplicação de carga não axial resultou em diferenças estatisticamente significantes para os grupos G3 versus G4 e G2 versus G4. Já a análise estatística dos dados de variação do parâmetro BV/TV, mostrou diferença estatisticamente significante para todas as comparações na área óssea intra-rosca após aplicação de carga oclusal e lateral. A análise estatística do parâmetro BIC mostrou diferenças significantes para os grupos de baixa densidade (G3 e G4) nas comparações pós implante e pós carga. Em relação aos dados de variação, pode-se constatar diferença estatisticamente significante na aplicação de carga axial para G1 versus G2 e G2 versus G4, enquanto a aplicação de carga lateral mostrou diferença estatisticamente significante para as comparações G1 versus G3 e G2 versus G4. De acordo com os dados obtidos pode-se concluir que a densidade óssea tem relação com a estabilidade primária de implantes, que cargas não axias são prejudiciais para o tecido ósseo peri-implantar e que o posicionamento infraósseo pode promover melhor resposta do tecido ósseo, principalmente em regiões de baixa densidade óssea.With the increase of oral rehabilitation with implants, immediate load can be used to reduce the treatment time. It is important to perform correct treatment planning for immediate implant loading, using 3D image analysis. The subcrestal implant positioning is one of the possible factors that may impact the success of immediate loading implants. Objective: The aim of this study is to evaluate the initial stability of osseointegrated implants placed infra bone or at the bone level in standardized porcine bone cylinders, through image (microcomputerized tomography) and mechanical analysis (resonance frequency, insertion torque and pull out test). Sixty bone cylinders were prepared from fresh porcine bone and separated in 2 groups: Group A 30 cylinders removed from femur head (high bone density) and Group B - 30 cylinders removed from the mandibular condyle (low bone density). Before the experimental procedure, the bone cylinders were certificated through 2D images analysis (digital radiography) to calculated bone density. After this, the bone cylinders were evaluated through micro computed three-dimensional analysis before the implant insertion. The parameters were analyzed in 2 levels (L1-bone volume internal to the threads and L2 - immediately adjacent to the end of threads). The microtomographical parameters analyzed were: Bone volume/Total volume (BV/TV), Trabecular thickness (TbSp), Bone surface/Volume ratio (BS/BV) and Total porosity percent (POTOT). Then, 60 implants (Alvim, 3.5 mm x 10 mm, Neodent®, Curitiba) were inserted in bone cylinders (1 implant in each cylinder), according to manufacturers protocol, and insertion torque was recorded for each implant. After that, the bone cylinders were submitted a new micro computed tomography analysis that evaluated the same levels and parameters, and Bone Implant Contact (BIC) was also recorded. After that, 5 implants were submitted to pull out test while the others implants received axial and non- axial load. After that, a new microcomputerized tomography analysis evaluated the same levels and parameters previously described, and resonance frequency analysis and pullout test were performed in the bone cylinders. 3D analysis showed that pre- and post-implants intra-groups had statistically significant differences for TbSp and POTOT parameters, and for BSBV and BIC parameters there were observed statistically significant differences for low bone densities groups. The values of differences between post and before loading showed statistically significant differences between G2 and G4 for TbSp, POTOT, BSBV, BV/TV and BIC parameters. The RFA analysis showed highest values for G2 and G4. Concerning insertion torque, the highest mean values were found in high bone densities groups. The pullout strength test showed that the non- axial loads in the low bone density maybe lead to implant displacement throughout the implant insertion axis. Bone density has a direct relationship with implant primary stability. Non- axial loads are harmful to peri- implantar bone tissue and subcrestal placement of implants presented the best mechanical and tomographical results.
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Schneider, James A. "Analysis of piezocone data for displacement pile design." University of Western Australia. School of Civil and Resource Engineeringd%695 Electronic theses, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0207.
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Due to the similarity between the geometry and full displacement installation method of a cone penetrometer and displacement pile, the axial capacity of displacement piles is often assessed using data from a cone penetration test (CPT). As there are many more factors influencing pile axial capacity than affecting CPT cone resistance, there are a wide range of CPT-based empirical design methods in use. These methods have various levels of predictive success, which usually depends upon the soil conditions, pile geometry, pile installation method, and time between installations and loading. An improved understanding of the basis and reliability of respective design methods is essential to improve the quality of predictions in the absence of site specific load test data. This thesis explores the influence of soil state and drainage conditions on piezocone penetration test (CPTU) tip resistance (qc) and penetration pore pressures (u2). For cone penetration testing identified as 'drained', factors influencing the correlation between cone tip resistance and displacement pile shaft friction in sand are investigated through (i) a review of previous research and the performance of existing design methods; (ii) centrifuge studies of piles of differing widths with measurements of local lateral stress; (iii) field tension tests at different times between installation and loading for uninstrumented driven piles with different diameters and end conditions; and (iv) field tension tests at different times between installation and loading on closed ended strain gauged jacked segmented model piles with different installation sequences. CPTU qc and u2 are primarily controlled by soil state and drainage conditions, with effective stress strength parameters and soil stiffness also influencing the measurements. The primary mechanisms identified to control the correlation between cone tip resistance and shaft friction on displacement piles are identified as; (i) the initial increase in radial stress due to soil displaced during installation of a pile; (ii) different levels of soil displacement induced by open, closed, and partially plugged piles; (iii) reduction in radial stress behind the pile tip; (iv) additional reduction in radial stress with continued pile penetration (friction fatigue); (v) changes in radial stress during loading; (vi) constant volume interface friction angle between soil and steel; and (vii) changes in the effects of the above mentioned mechanisms with time between installation and loading. The relative effect of each of these factors is investigated in this thesis.
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Shamsai, Mohammad. "Prefabricated cage system for reinforcing concrete members." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1141744526.
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Sorensen, Taylor J. "Reducing Thermal Bridging and Understanding Second-Order Effects in Concrete Sandwich Wall Panels." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7642.
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Structural engineers have traditionally detailed structures with structural and fabrication efficiency in mind, but often based on a limited understanding of thermal efficiency. Some connection designs can create significant thermal bridging, leading to unnecessary heat transfer and even premature degradation through condensation. Thermal bridging occurs when heat transfer is given a path through a more conductive material like concrete or steel rather than insulation. Concrete sandwich wall panels (SWP) tend to be highly efficient at preventing heat transfer in the middle of panels, with greatest heat transfer occurring at connections. This project identified thermally efficient details for future SWP construction to reduce heat transfer, lessen environmental impact, and increase sustainability of SWP structures. It can be particularly difficult to avoid thermal bridging at corbel connections, so 12 corbel specimens were created and tested to provide alternative corbel design options for engineers. Nine details were successfully created and are presented. Corbel specimens were modeled using the Beam-Spring Method with good agreement. After validating the Beam-Spring Model, a parametric study investigated effectiveness of the PCI Second Order Analysis and the effect of length, panel stiffness, and wythe configuration on SWP behavior under axial and flexural loads.
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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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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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Zand, Behrad. "Modeling of composite laminates subjected to multiaxial loadings." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1189468229.
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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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