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1
Tarbadar, Rima. "Étude expérimentale en vraie grandeur et modélisation des pressions induites par le vent dans les combles : application à l'étanchéité des toitures à l'eau." Châtenay-Malabry, Ecole centrale de Paris, 1995. http://www.theses.fr/1995ECAP0414.
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La pénétration d'eau de pluie à travers une toiture à pentes constituée de petits éléments est principalement liée à la différence de pression externe et interne, générée par le vent sur le toit. Le champ de pression externe est accessible aux mesures, sur maquette en soufflerie atmosphérique. En revanche, le champ de pression interne ne peut pas être obtenue qu'en vraie grandeur. Une modélisation numérique de ce dernier a donc fait l'objet de cette thèse. Il s'agit plus précisement de calculer la pression instantanée en sous-face de la couverture, dotée ou non d'un écran qu'il soit souple ou rigide. L'estimation de la pression interne est délicate faute d'une bonne connaissance des caractéristiques de l'écoulement à travers des parois perméables. Une campagne de mesures en vraie grandeur a donc été menée pour caractériser la perméabilité à l'air de la toiture pour un revêtement donné (banc de mesures), ensuite pour étudier les effects de la vitesse et de la turbulence du vent et de l'intensité de la pluie sur cette perméabilité (soufflerie climatique). La pression interne issue du modèle sans écran reproduit bien celle mesurée. L'étude paramétrique du cas avec écran à montré la possibilité de réduire considérablement la pression différentielle. Une bonne connaissance des paramètres qui influencent le différentiel de pression permet de concevoir des toits à pentes, pour lesquels les problèmes de pénétration d'eau de pluie sont considérablement réduitsGenerally, the rain penetration through pitched lapped roofs is created by the difference of external and internal pressure, generated by the wind. In this thesis, a numerical model has been developped for prediction of internal pressure under the elements (the external pressure can be measured on a model in a boundary layer wind-tunnel). Two cases have been studied : roof without underlay, roof with flexible or stiff underlay. The dynamics of internal pressure is, in general, a complex problem. This is due to the poor knowledge on the leakage paths characteristics. Therefore, full-scale experimental studies have been carried out to characterize the roof wind permeability (test appartus) and to investigate the effects of windspeed, atmospheric turbulence and rain intensity on this permeability (climatic wind-tunnel). The analytical results were compared with full-scale results (roof without underlay case), and they matched closely. Parametric studies (underlay case) have shown that it is possible to reduce considerably the wind loads. Through a complete knowledge of the controlling parameters it will be possible to design and construct pitched lapped roofs, from which the problems of rain penetration is strongly reduced
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Lala, Rakotoson Serge Joseph. "Les interfaces géosynthétiques sous faible confinement au plan incliné." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10038.
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Devant les difficultes essentiellement administratives et sociales posees par l'ouverture de nouveaux sites de stockage de dechets, la tendance actuelle est a l'extension laterale ou verticale de centres existants, conduisant parfois a l'adoption de geometries de pente inhabituelles pour lesquelles la stabilite des systemes geosynthetiques d'etancheite en pente (sur talus ou en couverture) devient une question cruciale. La maitrise de la stabilite de tels systemes passe par une meilleure comprehension de leur fonctionnement. Dans ce but, l'etude de la caracterisation sur plan incline des interfaces geosynthetiques a ete menee, ainsi que celle du renforcement par inclusion de geosynthetique et l'analyse de la reponse d'un systeme geosynthetique d'etancheite en vraie grandeur. Cette etude se base principalement sur des essais de laboratoire realises sur un dispositif plan incline elabore dans le cadre de ce travail. La validite de la caracterisation sur plan incline des interfaces sable/geosynthetiques est confirmee par la repetabilite, la reproductibilite et la coherence des caracteristiques d'interface obtenues vis-a-vis des tendances generales observees en boite de cisaillement direct, relatives a l'influence du confinement. Le mecanisme d'ancrage constitue le principe de base du renforcement par inclusion de geosynthetique. Les essais de renforcement realises montrent particulierement une meilleure efficacite du renforcement par inclusion pour stabiliser le sol de couverture, par rapport au renforcement classique a la base du sol. L'analyse des donnees issues d'une experimentation en vraie grandeur sur un systeme geosynthetique d'etancheite illustre particulierement la difficulte de prediction du fonctionnement d'un systeme reel, due principalement aux incertitudes de la mise en place.
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Giraud, Hubert. "Renforcement des zones d'effondrement localisé : modélisations physique et numérique." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10199.
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Le renforcement des sols au moyen des geosynthetiques est en constante evolution. Cette technique, de part sa simplicite et son cout de mise en oeuvre modere, a deja atteint une certaine reconnaissance pour differentes applications telles que les murs de soutenement renforces (porteur ou non). Un programme de recherche (r. A. F. A. E. L. ) regroupant differents organismes (sncf, scetauroute, bidim geosynthetic s. A. , lrpc, lirigm) a ete mis en oeuvre pour developper une technique de renforcement par geosynthetiques sous les assises ferroviaires et autoroutieres dans les zones a risque. Des remblais experimentaux en vraie grandeur, sollicites par des effondrements localises, ont ete realises sur le site experimental d'eurre (drome) pour contribuer au developpement d'une methode de calcul appropriee a ce type de renforcement. Le dimensionnement des differentes structures experimentales, a pu se faire grace au developpement d'une formulation numerique originale en trois dimensions, d'un element de nappe textile par la methode des elements finis. Des etudes parametriques portant sur la nature du textile, du sol et des conditions d'ancrage sont presentees pour justifier des dispositions techniques retenues. La comparaison des resultats experimentaux et des calculs previsionnels, est tout a fait satisfaisante et montre les avantages et les limites d'une telle solution de renforcement.
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Grouhel, Marie-Christine. "Evolution de l'etat hygrothermique d'un toit experimental de tuiles de terre cuite durant son sechage." Paris 6, 1988. http://www.theses.fr/1988PA066273.
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La determination de l'evolution de l'etat hygrothermique d'un toit experimental de tuiles de terre cuite durant son sechage est effectuee a partir du modele mathematique de luikov et des equations des conditions aux limites de type fourier. On determine les coefficients thermophysiques et de transfert de masse de la terre cuite. Les coefficients de transferts de chaleur et de masse, dus a la convection en surface et en sous-face de la couverture, sont etudies en fonction des donnees meteorologiques. La resolution numerique du probleme de sechage suppose unidimensionnel est effectuee par une methode de differences finies
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Azim, Mohammad. "Contribution à la conception d'une station expérimentale pour l'étude du comportement des murs de soutènement." Paris 6, 1986. http://www.theses.fr/1986PA066337.
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Conception de cette structure par le laboratoire central des ponts et chaussées afin d'étudier expérimentalement le comportement de ce type d'ouvrage. Détermination des efforts internes dans le mur à l'aide de capteurs intégrés à la structure et étude du mécanisme de leur fonctionnement par des calculs aux éléments finis tridimensionnels, puis par photoélasticimétrie. On passe des mesures de déformation aux efforts internes dans la structure par des formules de régression linéaire qui résultent de l'analyse statistique d'un grand nombre de cas d'étalonnage sous sollicitations contrôlés. Détermination théorique des dimensions optimales à donner au remblai pour que les efforts dans le mur soient représentatifs d'un massif d'extension semi-infinie. L'étude est effectuée par un modèle numérique bidimensionnel aux éléments finis et également par des calculs bidimensionnels à l'aide d'un logiciel, utilisant également les éléments finis. Analyse des premiers essais réalisés à la station.
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Freuler, Richard Jeffrey. "An investigation of jet engine test cell aerodynamics by means of scale model test studies with comparisons to full-scale test results /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487758680159803.
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Gustafsson, Veronica. "Creep deformation of rockfill : Back analysis of a full scale test." Thesis, KTH, Jord- och bergmekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159189.
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With the purpose of studying the mechanical properties of uncompacted rockfill and the creep deformation behaviour of rockfill under a load as well as finding a suitable method for estimation of creep deformation behaviour, a full scale embankment loading experiment was performed. The results of this experiment were then evaluated. During the course of this study it became evident to the author that the deformations which were seen in the collected data from the experiment could be classified as creep deformations due to the linear decrease of the deformation against the logarithm of time and the study therefore came to focus on creep. One constitutive equation and one model for estimation of creep deformations were studied, and parameters were obtained through back analysis of experiment data as well as calculation of soil stresses. The creep model was based on a logarithmic approximation of the creep deformations and the creep equation was based on a power function. The creep model could also be simplified and evaluated as an equation and when a comparison was made between the equations and the measured results this showed that the logarithmic equation resulted in estimates closer to the measured deformations than what the power function did, therefore a logarithmic function is a better approximation to the deformations of the rockfill at Norvik than the power function. When the creep model was evaluated as intended, based on the soil stresses, the resulting creep estimates were less accurate, they was however still within the limits of what can be considered as admissible. The conclusion is that a logarithmic function describes the creep deformation of the rockfill at Norvik better than a power function and that the creep model by Kristensen is suitable for estimating the creep deformations. This since the creep model also provides a way of estimating deformations occurring under stress conditions other than the ones for which the creep test was performed.
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Edin, Erik, and Mattias Ström. "Comparing a full scale test with FDS, FireFOAM, McCaffrey & Eurocode." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-75616.
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In the rapidly growing field of CFD-calculations (Computational Fluid Dynamics), companies and organizations are bringing forth new tools, tools that display an image of a given fire scenario. These tools are developed because they provide time efficiency as well as a sustainable economic approach. Another useful tool is analytical solutions, these analytical solutions serve the same purpose as CFD-modeling, providing results of a given scenario. The purpose of this thesis was to simulate a fire plume with two different CFDprograms and compare the gas temperature from each simulation with a full-scale test. Also, analytical solutions were used to perform the same comparisons. Four different calculation models were utilized to obtain results. The CFD-programs were FDS (Fire Dynamics Simulator) and FireFOAM. The analytical solutions were performed using McCaffrey´s plume equation and Eurocode solutions for localized fire temperatures. FDS is a very well documented program, due to this, problems that arose were easily fixed. The structure of FDS enables the user to maneuver the program easily. SmokeView was used to visualize the simulation. FireFOAM is written in C++ and is operated through the command prompt. The structure of the program was time-consuming to understand mainly because of two reasons, primarily because the authors lack of knowledge in coding in C++, and second because of the LINUX environment. Moreover, the process of working in FireFOAM was mostly through trial and error. On some occasions, issues arose that could be solved by communication with other CFD users at CFD-Online. When major problems occurred, regarding the code or other CFD issues, Johan Anderson at RISE Research Institutes of Sweden guided us through most of these problems and enabled us to move forward with the work. ParaView was used to visualize the simulation, and Excel was used to evaluate the temperature data from the FDS- and FireFOAM simulations. For the calculations in FDS and FireFOAM, a sensitivity analysis was performed to see which grid size presented best results in each program. A grid size of 5 cm, 10 cm, and 20 cm were applied in FDS, and in FireFOAM the grid dimensions were set to 5 cm and 10 cm. The results showed that 5 cm was the most appropriate grid size for both programs. It would have been more favorably to simulate with several different grid sizes, to further strengthen the grid analysis. Though, due to the time frame of the thesis, further simulations were not performed. Calculations were repeated for the same scenario only with a lower HRR (Heat release rate). An extensive sensitivity analysis was conducted for FDS in the form of two different simulations. One simulation where HRR was the same as the full-scale test but with twice the area of the burner. In the second simulation, the same area was used on the burner as the fullscale test, but with half the HRR. Results from the analytical solutions were easy to achieve; however, the model has some limitations regarding calculations within the flame region. The estimated gas temperature, using FDS, aligns well with the full-scale test. The temperatures analyzed from FireFOAM deviated in general through the flame region and reached unreasonable high temperatures close to the ceiling. Since the analytical solutions were based on different conditions compared to those applied in the full-scale test, it was expected that the results should deviate. However, McCaffrey plume equations can still be used to give an approximate picture of scenarios similar to that of the full-scale test, and the same applies to Eurocode solutions for localized fire temperatures. Analysis of the results shows that FDS can be used to simulate similar scenarios. FireFOAM simulates a gas temperature that is overestimated within the flame region. One of the reasons for this was due to the grid size since the sensitivity analysis III showed that a refined grid size resulted in more correct temperature value, the reason for not simulating with a more refined grid size was due to the restricted time frame of this thesis. FireFOAM is, at present, recommended for researchers who wish to use the code for specific purposes. Therefore, given the same premises, FireFOAM is not recommended for the standard fire safety analysis.
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Carrea, Francesco. "Shake-table test on a full-scale bridge reinforced concrete column." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/1756/.
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DEL, TORO RIVERA RAUL. "Comportement des noeuds d'ossature en beton arme sous sollicitations alternees." Marne-la-vallée, ENPC, 1988. http://www.theses.fr/1988ENPCA004.
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Etude des joints sous sollicitation sismique sur la base de trois essais sur corps d'epreuve de grande dimensionm en analysant les mecanismes des glissements constates des armatures principales dans la partie centrale du noeud, et le type de rupture a laquelle cela donne lieu; etude sur la base d'un essai de la possibilite d'utiliser un beton de fibres metalliques avec ferraillage transversal reduit
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Lau, Yip Hang. "Maximization of treatment capacity of a full-scale biological nitrogen removal plant through model simulation and full-scale stress test /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202005%20LAU.
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Dalley, Sam. "Wind tunnel measurements on a low rise building and comparison with full-scale." Thesis, University of Surrey, 1993. http://epubs.surrey.ac.uk/886/.
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Walsh, J. Matthew. "Full-scale lateral load test of a 3x5 pile group in sand /." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd955.pdf.
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Walsh, James Matthew. "Full-Scale Lateral Load Test of a 3x5 Pile Group in Sand." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/605.
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Although it is well established that spacing of piles within a pile group influences the lateral load resistance of that group, additional research is needed to better understand trends for large pile groups (greater than three rows) and for groups in sand. A 15-pile group in a 3x5 configuration situated in sand was laterally loaded and data were collected to derive p-multipliers. A single pile separate from the 15-pile group was loaded for comparison. Results were compared to those of a similar test in clays. The load resisted by the single pile was greater than the average load resisted by each pile in the pile group. While the loads resisted by the first row of piles (i.e. the only row deflected away from all other rows of piles) were approximately equal to that resisted by the single pile, following rows resisted increasingly less load up through the fourth row. The fifth row consistently resisted more than the fourth row. The pile group in sand resisted much higher loads than did the pile group in clay. Maximum bending moments appeared largest in first row piles. For all deflection levels, first row moments seemed slightly smaller than those measured in the single pile. Maximum bending moments for the second through fifth rows appeared consistently lower than those of the first row at the same deflection. First row moments achieved in the group in sand appeared larger than those achieved in the group in clay at the same deflections, while bending moments normalized by associated loads appeared nearly equal regardless of soil type. Group effects became more influential at higher deflections, manifest by lower stiffness per pile. The single pile test was modeled using LPILE Plus, version 4.0. Soil parameters in LPILE were adjusted until a good match between measured and computed responses was obtained. This refined soil profile was then used to model the 15-pile group in GROUP, version 4.0. User-defined p-multipliers were selected to match GROUP calculated results with actual measured results. For the first loading cycle, p-multipliers were found to be 1.0, 0.5, 0.35, 0.3, and 0.4 for the first through fifth rows, respectively. For the tenth loading, p-multipliers were found to be 1.0, 0.6, 0.4, 0.37, and 0.4 for the first through fifth rows, respectively. Design curves suggested by Rollins et al. (2005) appear appropriate for Rows 1 and 2 while curves specified by AASHTO (2000) appear appropriate for subsequent rows.
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Karikari-Boateng, Kwaku Ampea. "Accelerated testing of tidal turbine main bearing in a full scale nacelle test rig." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/31210.
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Tidal Energy is one of the growing renewable energy technologies that is aimed at tackling global energy challenges. The Horizontal Axis Tidal Turbine (HATT) is an in-stream Tidal Energy Converter (TEC) which extracts kinetic energy from tidal flows. These tidal turbines face many reliability challenges due to their complexity, harsh operating environment and low accessibility. One of the component contributing significantly to the reliability of a TEC is the bearing supporting the rotating shaft within the nacelle. The reliability assessment of this component is essential during the design process and before their eventual deployments. This work is describes shaft bearing reliability assessment procedures. In recent years, the Offshore Renewable Energy (ORE) Catapult’s National Renewable Energy Centre has developed a dedicated multi axis test facility for full scale testing of tidal turbine nacelles and components (i.e. Nautilus). This work presents a methodology for testing tidal turbine shaft bearings in a representative manner in the full scale nacelle test rig, Nautilus. Two aspects are considered, namely the damage assessment and the damage replication in an accelerated manner. The damage assessment process considers the global loading on the shaft bearing and a Rigid Dynamics (RD) model has been applied to identify the local bearing loads. Local loads are converted to stress enabling the identification of stress-life relationship and bearing damage. The damage replication process is aimed to evaluate the 20 year damage and the Acceleration by Phase-shift (AbP) method has been developed to accelerate the cumulative damage. The AbP method enables the assessment of performance characteristics of shaft bearings in a laboratory environment, reducing failure rates, validate performance in a cost effective manner by reduced testing times. Within this work, novel processes for shaft bearing reliability assessments and demonstration are suggested and it concludes with the presentation of a recommended test plan for carrying out accelerated tests on a full scale bearing.
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Christensen, Dustin Shaun. "Full Scale Static Lateral Load Test of a 9 Pile Group in Sand." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1267.pdf.
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Taylor, Amy Jean. "Full-scale-lateral-load test of a 1.2 m diameter drilled shaft in sand /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1263.pdf.
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McCall, Amy Jean Taylor. "Full-Scale-Lateral-Load Test of a 1.2 m Diameter Drilled Shaft in Sand." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/403.
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The soil-structure interaction models associated with laterally loaded deep foundations have typically been based on load tests involving relatively small diameter foundations. The lateral soil resistance for larger diameter foundations has been assumed to increase linearly with diameter; however, few, if any load tests have been performed to confirm this relationship. To better understand the lateral resistance of large diameter deep foundations in sand, a series of full scale, cyclic, lateral load tests were performed on two 1.2 m diameter drilled shafts and a 0.324 m diameter steel pipe pile in sand. Although the tests involve two different foundation types, the upper 2.4 m of the profile, which provides the majority of the lateral resistance, consists of sand compacted around both foundation types. Therefore, these test results make it possible to evaluate the effect of foundation diameter on lateral soil resistance. The drilled shafts were first loaded in one direction by reacting against a fifteen-pile group. Subsequently a load test was performed in the opposite direction by reacting against a 9-pile group. The soil profile below the 2.4 m-thick layer of compacted sand consisted of interbedded layers of sand and fine-grained soil. For the drilled shaft load tests, pile head deflection and applied load were measured by string potentiometers and load cells, respectively. Tilt was also measured as a function of depth with an inclinometer which was then used to calculate deflection and bending moment as a function of depth. For the pipe pile, deflection and applied load were also measured; however, bending moment was computed based on strain gauges readings along the length of the pile. The lateral response of the drilled shafts and pipe pile were modeled using the computer programs LPILE (Reese et al., 2000), SWM6.0 (Ashour et al., 2002), and FB-MultiPier Version 4.06 (Hoit et al., 2000). Comparisons were made between the measured and computed load-deflection curves as well as bending moment versus depth curves. Soil parameters in the computer programs were iteratively adjusted until a good match between measured and computed response of the 0.324 m pipe pile was obtained. This refined soil profile was then used to model the drilled shaft response. User-defined p-multipliers were selected to match the measured results with the calculated results. On average very good agreement was obtained between measured and computed response without resorting to p-multipliers greater than 1.0. These results suggest that a linear increase in lateral resistance with foundation diameter is appropriate. LPILE typically produced the best agreement with measured response although the other programs usually gave reasonable results as well. Cyclic loading generally reduced the lateral resistance of the drilled shafts and pile foundation by about 20%.
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Kevan, Luke Ian. "Full-Scale Testing of Blast-Induced Liquefaction Downdrag on Driven Piles in Sand." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6966.
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Deep foundations such as driven piles are often used to bypass liquefiable layers of soil and bear on more competent strata. When liquefaction occurs, the skin friction around the deep foundation goes to zero in the liquefiable layer. As the pore pressures dissipate, the soil settles. As the soil settles, negative skin friction develops owing to the downward movement of the soil surrounding the pile. To investigate the magnitude of the skin friction along the shaft three driven piles, an H-pile, a closed end pipe pile, and a concrete square pile, were instrumented and used to measure soil induced load at a site near Turrell, Arkansas following blast-induced liquefaction. Measurements were made of the load in the pile, the settlement of the ground and the settlement of piles in each case. Estimates of side friction and end-bearing resistance were obtained from Pile Driving Analyzer (PDA) measurements during driving and embedded O-cell type testing. The H-pile was driven to a depth of 94 feet, the pipe pile 74 feet, and the concrete square pile 72 feet below the ground surface to investigate the influence of pile depth in response to liquefaction. All three piles penetrated the liquefied layer and tipped out in denser sand. The soil surrounding the piles settled 2.5 inches for the H-pile, 2.8 inches for the pipe pile and 3.3 inches for the concrete square pile. The piles themselves settled 0.28 inches for the H-pile, 0.32 inches for the pipe pile, and 0.28 inches for the concrete square pile. During reconsolidation, the skin friction of the liquefied layer was 43% for the H-pile, 41% for the pipe pile, and 49% for the concrete square pile. Due to the magnitude of load felt in the piles from these tests the assumption of 50% skin friction developing in the liquefied zone is reasonable. Reduced side friction in the liquefied zone led to full mobilization of skin friction in the non-liquefied soil, and partial mobilization of end bearing capacity. The neutral plane, defined as the depth where the settlement of the soil equals the settlement of the pile, was outside of the liquefied zone in each scenario. The neutral plane method that uses mobilized end bearing measured during blasting to calculate settlement of the pile post liquefaction proved to be accurate for these three piles.
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Conlee, Carolyn T. Gallagher Patricia M. "Dynamic properties of colloidal silica soils using centrifuge model tests and a full-scale field test /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3248.
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Otaki, Takeshi. "SIZE EFFECTS IN SHEAR FAILURE OF REINFORCED CONCRETE BRIDGE COLUMNS - FULL SCALE TEST AND ANALYTICAL EVALUATION." Kyoto University, 2001. http://hdl.handle.net/2433/150668.
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Kirkov, Kirko Dimitar. "Tearing resistance for fillet welds in ships exposed to grounding : a full scale test & cost implications." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11671.
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Kjellstrand, Robert. "Hydraulic Behaviour in an Activated Sludge Tank : From Tracer Test through Hydraulic Modelling to Full-Scale Implementation." Licentiate thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3390.
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Hydraulic behaviour in a large denitrifying activated sludge tank, located at the Rya Wastewater treatment plant (WWTP) in Göteborg Sweden, was investigated and optimized by using fullscale tracer test and hydraulic modelling. The Rya WWTP is a high loaded plant with a small footprint. Expansion of the site is limited due to several restrictions. An efficient use of already existing facilities is therefore of great importance in order to meet the demands of decreased effluent limits, set by authorities. The presence of a short circuiting stream was identified with full-scale tracer tests and the hydraulic situation was successfully quantified using the Martin model, a compartment model based on curve fitting to the residence time distribution curve (RTD-curve) from the full-scale tracer test. Computational fluid dynamics (CFD) 3D modelling was used for virtual prototyping of different corrective measures near the inlet to break the previously identified short circuiting stream. From an operational point of view, inlet baffles were chosen as the preferable alternative. After implementation, improved tank hydraulics, were verified with another full-scale tracer test. At a normal flow (3.6 m3/s), the space time in the tank was found to be 16 minutes. In the original tank 30 % of the water had a residence time of less than 8 minutes, 49 % of the water had a residence time between 8 and 24 minutes and 21 % of the water had a residence time of more than 24 minutes. After implementation of corrective measures, the tank with baffles had 6 % of the water with a residence time of less than 8 minutes. 77 % of the water had a residence time between 8 and 24 minutes and 17 % of the water had a residence time of more than 24 minutes. Also, the mixing characteristics in the tank achieved a more plug-flow like character. Full-scale tracer tests are very informative when investigating hydraulic situations in activated sludge tanks. Mathematical modelling using black box approach can help to quantifying the hydraulics in a tank. For example can use of the Martin model help to quantify short circuiting streams and dead volumes. CFD modelling is a useful and informative tool for analyzing problematic hydraulics at wastewater treatment plants and for the design of theoretical corrective measures. Being a useful tool for virtual prototyping, this type of modelling also deserves to have a more central role when designing large reactors and other hydraulic systems.I. Short Circuiting in a Denitryfying Activated Sludge Tank.
R. Kjellstrand, A. Mattsson, C. Niklasson and M.J. Taherzadeh.
Water Science & Technology, Vol. 52, No. 10-11, pp 79-87, IWA Publishing 2005. II. Improved Hydraulic Behaviour in a Denitrifying Activated Sludge Tank.
R. Kjellstrand, A. Mattsson.
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Hollenbaugh, Joseph Erick. "Full-Scale Testing of Blast-Induced Liquefaction Downdrag on Auger-Cast Piles in Sand." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5494.
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Deep foundations like auger-cast piles and drilled shafts frequently extend through liquefiable sand layers and bear on non-liquefiable layers at depth. When liquefaction occurs, the skin friction on the shaft decreases to zero, and then increases again as the pore water pressure dissipates and the layer begins to settle, or compact. As the effective stress increases and the liquefiable layer settles, along with the overlaying layers, negative skin from the soil acts on the shaft. To investigate the loss of skin friction and the development of negative skin friction, soil-induced load was measured in three instrumented, full-scale auger-cast piles after blast-induced liquefaction at a site near Christchurch, New Zealand. The test piles were installed to depths of 8.5 m, 12 m, and 14 m to investigate the influence of pile depth on response to liquefaction. The 8.5 m pile terminated within the liquefied layer while the 12 m and 14 m piles penetrated the liquefied sand and were supported on denser sands. Following the first blast, where no load was applied to the piles, liquefaction developed throughout a 9-m thick layer. As the liquefied sand reconsolidated, the sand settled about 30 mm (0.3% volumetric strain) while pile settlements were limited to a range of 14 to 21 mm (0.54 to 0.84 in). Because the ground settled relative to the piles, negative skin friction developed with a magnitude equal to about 50% of the positive skin friction measured in a static pile load test. Following the second blast, where significant load was applied to the piles, liquefaction developed throughout a 6-m thick layer. During reconsolidation, the liquefied sand settled a maximum of 80 mm (1.1% volumetric strain) while pile settlements ranged from 71 to 104 mm (2.8 to 4.1 in). The reduced side friction in the liquefied sand led to full mobilization of side friction and end-bearing resistance for all test piles below the liquefied layer and significant pile settlement. Because the piles generally settled relative to the surrounding ground, positive skin friction developed as the liquefied sand reconsolidated. Once again, skin friction during reconsolidation of the liquefied sand was equal to about 50% of the positive skin friction obtained from a static load test before liquefaction.
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Bratlie, Andreas, and Christian Bergstrøm Hillestad. "Impact on Duplex Steel Pipes with Precipitated Sigma-phase : Modeling a Full-scale Impact Test on Pipe Fittings." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18722.
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Duplex stainless steel (DSS) is a common material in offshore pipe fittings. A manufacturing defect has altered the behavior of the components through an erroneous heat treatment, which has led to precipitation of 𝜎-phase. A report showing a strong correlation between precipitated 𝜎-phase and the reduction in impact toughness, initiated a great interest in the offshore industry for further studies of the effect of precipitated 𝜎-phase in DSS pipe fittings. In this thesis a numerical approach to simulate the behavior of duplex stainless steel with precipitated 𝜎-phase has been performed. The simulations have been done using the Gurson material model, which is implemented in the user defined material model in the SIMLab Metal Model. In addition the material model has been combined with a brittle fracture criterion. The results deviate from the observations done in the laboratory. The reasons for the deviations were found to be quite complex, but effects from mesh sensitivity and incorrect material optimization was found. The influence of the Gurson model is limited for the specimens acting in a brittle manner. It is therefore considered unnecessary to apply this material model for these problems.
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Dupray, Sebastien. "Integrity of rock blocks for armouring of hydraulic works : towards full-scale test to predict mass distribution changes." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420579.
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Draier, Benny. "Test vector generation and compaction for easily testable PLAs." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63970.
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Cummings, W. Mark. "Smoke Movement Analysis (Smoke Transport Within a Corridor)." Digital WPI, 2004. https://digitalcommons.wpi.edu/etd-theses/1088.
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"A series of full-scale fire tests were performed, using a fire compartment and an adjoining long (30+ m) corridor, as part of an effort to quantify the dynamics associated with smoke transport within a corridor. The tests were performed at the U.S. Coast Guard Research and Development Center’s Fire and Safety Test Detachment in Mobile, Alabama on board the Test Vessel Mayo Lykes. The resulting empirical data was analyzed in an effort to develop a method that could be used to estimate the movement of smoke within a corridor. The objective is to potentially incorporate this method into a smoke movement analysis “tool†that could, in turn, be used in conjunction with a fire safety analysis methodology previously developed by the U.S. Coast Guard; the Ship fire Safety Engineering Methodology (SFSEM). The goal is to develop a smoke movement analysis “module†that can be utilized in conjunction with the SFSEM when conducting an overall fire safety analysis of a ship. Of particular interest is the speed at which the smoke propagates along the length of the corridor. The focus of a smoke movement module would be life safety. A conservative assumption is made that if smoke is present in sufficient quantities to fill a corridor, then the corridor is to be considered untenable and not available as a means of egress. No attempt is made to address toxicity or density issues associated with smoke. This analysis developed correlations for the corridor smoke velocity, both as a function of the heat release rate of the associated fire and the upper layer temperatures within the fire compartment. Problems associated with the data collection and the narrow range of fire sizes used had a detrimental impact on the confidence level in the correlation based on heat release rate. The data do appear to confirm the results of previous efforts that indicated a weak relationship between the heat release rate and smoke velocity, on the order of the one-third to one-fourth power. The temperature data tended to be less problematic. This correlation shows promise for potential use with both the SFSEM and other existing computer models/routines. However, unlike previous studies of this relationship, the results of these data suggest that the velocity-temperature relationship is linear and not a square-root function. The test data were compared to predictive results using the CORRIDOR routine within FPETOOL. In general, the CORRIDOR results provided a reasonable good correlation to the tests data. Both the wave depth and temperature loss within the wave, as a function of distance, were consistently over-predicted. The velocity results were mixed, but were generally within 20 percent of the test data. The results of this study show promise, with respect to developing a correlation that can be used a method for predicting smoke movement in a corridor. However, due to the questionable nature of some of the data estimates, coupled with both a lack of sufficient number of tests and a limited range of fire sizes used, additional test data will be required to further validate the accuracy and refine the correlation(s) suggested by this work."
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Nuttayasakul, Nuthaporn. "Experimental and Analytical Studies of the Behavior of Cold-Formed Steel Roof Truss Elements." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29765.
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Cold-formed steel roof truss systems that use complex stiffener patterns in existing hat shape members for both top and bottom chord elements are a growing trend in the North American steel framing industry. When designing cold-formed steel sections, a structural engineer typically tries to improve the local buckling behavior of the cold-formed steel elements. The complex hat shape has proved to limit the negative influence of local buckling, however, distortional buckling can be the controlling mode of failure in the design of chord members with intermediate unbraced lengths. The chord member may be subjected to both bending and compression because of the continuity of the top and bottom chords. These members are not typically braced between panel points in a truss.
Current 2001 North American Specifications (NAS 2001) do not provide an explicit check for distortional buckling. This dissertation focuses on the behavior of complex hat shape members commonly used for both the top and bottom chord elements of a cold-formed steel truss. The results of flexural tests of complex hat shape members are described. In addition, stub column tests of nested C-sections used as web members and full scale cold-formed steel roof truss tests are reported.
Numerical analyses using finite strip and finite element procedures were developed for the complex hat shape chord member in bending to compare with experimental results. Both elastic buckling and inelastic postbuckling finite element analyses were performed. A parametric study was also conducted to investigate the factors that affect the ultimate strength behavior of a particular complex hat shape.
The experimental results and numerical analyses confirmed that modifications to the 2001 North American Specification are necessary to better predict the flexural strength of complex hat shape members, especially those members subjected to distortional buckling. Either finite strip or finite element analysis can be used to better predict the flexural strength of complex hat shape members. Better understanding of the flexural behavior of these complex hat shapes is necessary to obtain efficient, safe design of a truss system. The results of these analyses will be presented in the dissertation.Ph. D.
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Haggerty, Daniel. "A Comparison of Predicted Brace Loads in Temporary Retaining Structures and Observed Brace Loads in Two Full Scale Test Sections." ScholarWorks@UNO, 2003. http://scholarworks.uno.edu/td/51.
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This thesis presents analyses of the results of a geotechnical instrumentation program performed by Eustis Engineering Company for the U.S. Army Corps of Engineers (USACE) during the construction of two covered canals in New Orleans, Louisiana. At each site, a cast-in-place concrete culvert was constructed within a sheeted and braced excavation. Information provided by Eustis Engineering Company to the USACE is presented describing the existing soil conditions, the construction schedule, the geotechnical testing apparatus and instrumentation, and the data produced from the geotechnical instrumentation program. In this thesis, several theoretical approaches available for estimating the strut loads in braced excavations were examined and used to predict the strut loads at the two construction sites. These theoretical approaches included Coulomb pressures diagrams, Terzaghi pressure diagrams, and soil-structure interaction. The results of the theoretical strut load prediction methods are presented and compared with the results of the geotechnical instrumentation program data.
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Wang, Shujiao. "Exploring the washback of a large-scale high-stakes Chinese test, the Hanyu Shuiping Kaoshi, on learner factors." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119765.
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Washback research has tended to focus on whether washback exists and whether there is intended washback brought about by examinations in English as a second/foreign language (ESL/EFL contexts). This study, on the other hand, investigated how learner factors, such as learning strategies and beliefs, related to the washback of a large-scale high-stakes Chinese second language proficiency test, the Hanyu Shuiping Kaoshi (HSK). Using a mixed-methods research (MMR) approach, quantitative data were collected from Chinese as a second/foreign/heritage language (CSL) learner survey responses (n = 60) and qualitative data were elicited from 8 interviews and HSK related documents. Findings revealed that, an increasing number of people wanted to learn Chinese and take the HSK because they were interested not only in the Chinese language and culture, but also hoped to study, work or travel in China. They felt that becoming HSK-certified, helped them feel more motivated to learn Chinese and increased job opportunities. Thus, there were significant washback effects of the HSK on learning Chinese. Similar to previous research on washback, however, this study showed that the HSK had positive impact on some learners but negative effects on others. The finding showed statistically significant differences between regular Chinese learning (e.g., CSL courses, distance learning, or self-learning) and HSK test-specific learning among the four skills - speaking, listening, reading and writing. Significant predictors for the change in learning strategies between regular and test-specific learning were nationality, language proficiency, HSK performance and motivation. Finally, although it is claimed that the validity and reliability of the HSK content are high, this study points to some aspects that could be improved, such as including more subjective question forms and emphasizing the output (speaking and writing) measurements. This study has implications for HSK test developers, CSL teachers and CSL learners.Les recherches sur le washback, qu'on définit comme l'impact des examens déterminants sur l'enseignement et l'apprentissage, tentent de se questionner sur l'existence du washback en général ainsi que sa présence prévue par des épreuves d'anglais comme langue seconde ou étrangère. Cependant, cette étude s'est plutôt penchée sur la manière dont le profil de l'apprenant, soit ses stratégies d'apprentissage ainsi que ses croyances, influe sur le washback (l'effet en retour) d'une épreuve rigoureuse de langue chinoise à grande échelle appelée le Hanyu Shuiping Kaoshi (HSK). À l'aide d'une approche de méthodes mixtes de recherche, nous avons recensé des données quantitatives issues d'un sondage auprès des apprenants du chinois comme langue seconde/étrangère/maternelle. Pour ce qui est des données qualitatives, elles ont été tirées de huit entrevues et de plusieurs documents faisant référence au HSK. Les résultats ont révélé que le nombre d'apprenants du chinois ne cesse d'accroître et qu'ils ont choisi de faire le HSK parce qu'ils avaient l'intention d'étudier, de travailler ou de voyager en Chine, en plus de leur vif intérêt pour la langue et la culture chinoises. Ces étudiants se sont rendu compte que le fait de réussir le HSK les a aidés à gagner davantage de motivation à apprendre le chinois et à élargir leur champ de débouchés. Ainsi, l'impact du HSK s'avérait significatif sur l'apprentissage de la langue chinoise. Bien que cette étude soit analogue à des recherches antérieures sur le washback, elle a démontré que l'impact du HSK s'avérait positif chez certains apprenants, mais négatif chez d'autres. D'un point de vue statistique, les conclusions de la présente recherche ont souligné des différences significatives entre les cours réguliers du chinois et ceux basés sur le HSK en ce qui concerne quatre compétences : l'oral, l'écoute, la lecture et l'écriture. Parmi les principaux facteurs jouant un rôle sur la variété des stratégies d'apprentissage, on retrouvait la nationalité, la maîtrise de la langue, la performance du HSK et la motivation. Finalement, même si la validité et la fiabilité du contenu du HSK apparaissent élevées, cette étude révèle certains aspects qui pourraient être améliorés, soit l'ajout de structures interrogatives subjectives et l'emphase sur les outils d'évaluation du sortant, c'est-à-dire l'expression orale et l'écriture. Cette recherche constitue donc une référence incontournable pour les concepteurs du HSK, pour les enseignants et pour les apprenants du chinois langue seconde.
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Klinck, Amanda. "An Experimental Investigation of the Fire Characteristics of the University of Waterloo Burn House Structure." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/774.
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This thesis reports on the procedure, results and analysis of four full scale fire tests that were performed at the University of Waterloo's Live Fire Research Facility. The purpose of these tests was to investigate the thermal characteristics of one room of the Burn House structure. Comparisons were made of Burn House experimental data to previous residential fire studies undertaken by researchers from the University of Waterloo. This analysis showed similarities in growth rate characteristics, illustrating that fire behaviour in the Burn House is typical of residential structure fire behaviour. The Burn House experimental data was also compared to predictions from a fire model, CFAST. Recommendations were made for future work in relation to further investigation of the fire characteristics of the Burn House.
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Thorbjörnson, Lind Thomas. "Rockfalls from rock cuts beside Swedish railroads : A full scale fieldtest, to investigate rockfalls and how rock bounces." Thesis, KTH, Jord- och bergmekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185583.
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Rockfalls is a major problem around the world, if they occur in populated areas, they can cause major damage to infrastructure, injure or kill people. For this reason, it is important to be able to predict where the risk of rockfalls and how to prevent and protect populated areas from them. However, it is no easy task to predict rockfalls. Although if an area with potential area for rockfall is localized it may seem easy to construct protective meshing or bolting potential blocks down. But in many cases this is not easy to do due to practical issues or economic reasons, for example in rock cuts on older railways in Sweden. Fall heights from rock cuts like that are not particularly high but the risk of damage to the trains and infrastructure in the track area is high, however, it is unknown how extensive the damage may be. Trafikverket, the Swedish authority responsible for Sweden's roads and railways, has for some years investigated a new method for classifying and minimize the risk of rockfalls from rock cuts next to the railways. This study include aims to include the potential maximum distance of a block from the rockfall can travel to the existing method. This master's work is part of the investigation and will include full scale field test where the rockfalls are examined by filming them and then evaluate the “bounce coefficient”, coefficient of restitution, from the individual rockfalls using photogrammetric methods. During the field study, a geotechnical testing equipment, DCP test rig, to be evaluated for its ability of an easy way in the field to produce an estimated value on the coefficient of restitution. During the evaluation, two rockfall simulating software be used to investigate how well the results from them match the true blocks movements.Stenras är ett stort problem runtom i världen, om de inträffar i bebyggda områden kan de leda till stora skador på infrastruktur, skador eller dödsfall. Av den anledningen är det viktigt att kunna förutse vart det finns risk för stenras och hur man kan förebygga dem och skydda bebyggda områden från dem. Dock är det ingen lätt uppgift att förutse stenras. Även om det finns ett potentiellt område för stenras kan det tyckas lätt att placera ut skyddsnät eller bulta fast potentiella block. Men i många fall är detta inte praktiskt, eller ekonomiskt, till exempel i bergsskärningar på äldre järnvägar i Sverige. Fallhöjderna här är inte speciellt höga men risken för skador på tåg och infrastruktur i spårområdet är hög, dock är det okänt hur omfattande skadorna kan bli. Trafikverket, den svenska myndigheten som ansvarar för Sveriges vägar och järnvägar, har under flera år utrett en ny metod för att klassificera och minimera riskerna för stenras från bergskärningar bredvid järnvägar. Denna utredning syftar bland annat till att till att väga in det potentiella maximalt avstånd ett block från stenras kan färdas i den befintliga modellen. Det här mastersarbetet är en del i den utredningen och kommer att innefatta ett fullskaligt fältförsök där stenras undersöks genom att de filmas och sedan utvärderas studskoefficienten, coefficient of restitution, från de enskilda rasen i stereo. Under fältstudien kommer en geoteknisk testutrustning, DCP test rigg, att utvärderas för sin förmåga att lätt i fält få fram ett uppskattat värde på studskoefficienten. Under utvärderingen kommer två stenrassimuleringsprogram att användas för att undersöka hur väl de stämmer med de verkliga blockens rörelser.
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Snyder, Jeffrey L. "Full-Scale Lateral-Load Tests of a 3x5 Pile Group in Soft Clays and Silts." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd364.pdf.
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Saghebfar, Milad. "Performance of geotextile-reinforced bases for paved roads." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/18278.
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Doctor of PhilosophyDepartment of Civil Engineering
Mustaque Hossain
Geotextiles have been widely promoted for pavement structure over the past 30 years. However, there is a lack of well-instrumented, full-scale experiments to investigate the effect of geotextile reinforcement on the pavement design. In this study, full–scale accelerated tests were conducted on eight lanes of pavement test sections. Six out of these eight sections had granular bases reinforced with different types of woven geotextiles. The reinforced base sections and the control sections (with unreinforced base) were paved with Superpave hot-mix asphalt. Base and subgrade materials were the same for all sections while the test sections had different asphalt and base layer thicknesses. Each section was instrumented with two pressure cells on top of the subgrade, six strain gages on the geotextile body, six H-bar strain gages at the bottom of the asphalt layer, two thermocouples and one Time Domain Reflectometer (TDR) sensor. The sections were loaded to 250,000 to 500,000 repetitions of an 80-kN single axle load of the accelerated pavement testing machine. The mechanistic response of each section was monitored and analyzed at selected number of wheel passes. Results indicate that properly selected and designed geotextile-reinforced bases improve pavement performance in term of rutting and reduced pressure at the top of the subgrade. Finite element (FE) models were developed and verified using results from the full-scale accelerated pavement tests. The calibrated model was used to investigate the effects of geotextile properties on the pavement responses. FE analysis shows that benefits of reinforcement are more evident when stiffer geotextile is used.
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Petty, David A. "Full-Scale Testing of 40 Year Old Prestressed AASHTO Girders That Have Been Retrofitted in Shear by Externally Applied Carbon Fiber Reinforced Polymer Wraps." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/629.
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The Utah Department of Transportation (UDOT) is interested in the application of rehabilitation techniques to strengthen their AASTHO prestressed bridge girders for shear. Utah's bridges are exposed to deterioration from rain, snow, and the introduction of salt for ice removable. This requires innovative rehabilitation techniques to address the deteriorations of their highway bridges, especially the ends of bridge girders where water and salt are more common due to construction joints. Carbon Fiber Reinforced Polymers (CFRP) are becoming more prevalent as a tool in highway bridge rehabilitation. This research investigates the application of various CFRP systems that can be used as shear reinforcement for prestressed concrete girders. The experimental program involved full-scale destructive testing of six 40-year-old, AASHTO prestressed I-girders that were salvaged from the 45th South/I-215 bridge in Salt Lake City, Utah. The testing involved retrofitting five of the girders with various configurations of CFRP fabric. Based on the initial tests, the most effective configuration was then applied to another set of I-shaped concrete girders for verifications. After the experimental testing, two analytical models developed for predicting the additional shear contribution of the CFRP reinforcement were compared with the measured results from the experimental program. After testing and comparisons, a CFRP reinforcement configuration and theoretical model was selected as a reliable and effective method for application of external shear reinforcement of AASHTO prestressed I-shaped girders.
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Stillings, Tyler W. "Load Distribution and Ultimate Strength of an Adjacent Precast, Prestressed Concrete Box Girder Bridge." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1335463075.
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Deshmukh, Atul Ramesh. "Product Evaluation and Process Improvement Guidelines for the Personal Protective Equipment Manufacturers based on Human Factors, NIOSH Guidelines and System Safety Principles." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/26391.
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To analyze the system development, manufacturing practices and system evaluation procedures of representative PPES manufacturers, two companies (i.e., one â smallâ , referred to here as â simple manufacturer (SM)â , and one â largeâ , referred here as â complex manufacturer (CM)â â in terms of workforce, market presence, and capital) that develop first responder PPES, which voluntarily agreed to participate in the research were chosen. The complex PPES is an Air-Pak, a self contained breathing apparatus (SCBA) used by first responders for artificial breathing in life-threatening scenarios and the simple PPES is the Fire-Eye device, a thermal sensor that attaches to the visor of the firefighter in order to convey the visual warning of the ambient thermal environment. In order to differentiate the two distinct methodological approaches, the dissertation has been split into two different parts. The first methodology is a â case studyâ type of empirical investigation which follows a triangulation approach utilizing surveys, structured interviews, process and system observations, and examination of archival records. The second type of methodology is an experimental empirical research one, which involves laboratory-scale and full-scale real-life fire scenarios to conduct product evaluation.
The research goals of the case study research were to identify the problems faced by the manufacturers of PPES and to formulate guidelines with regards to manufacturing, compliance, design and development processes, etc., for the PPES manufacturers. The investigation sought answer to the following key questions: a) How do PPES manufacturers currently approach the systems design and development process and what best practices in manufacturing and quality control have they adopted? b) What human factors and ergonomic measures are adopted by these companies while designing their products and what human testing is conducted by companies? c)What safety measures are considered by the safety designer while designing the product?
The recommendations also include modifications to the product design process taking into account the market trends in the product design processes, involvement of ergonomics and safety aspects.
The research goals for the experimental part of this dissertation were to identify appropriate evaluation methods and conduct the PPES evaluation in simulated fire environments. The Fire-Eye device primarily functions in hot environments and warns the firefighters of the ambient temperature. Therefore, the laboratory-scale evaluation was conducted using test methods such as the Static Oven, Fire Equipment Evaluator, and Radiant Panel, methods which represent controlled environment test conditions. The Fire-Eye device was also evaluated in realistic fire environment created in an ISO burn room by conducting several tests using different types of fuels such as Heptane, Natural Gas, and Living-room set-up (i.e., furniture as fuel). The Fire-Eye device was tested for repeatability and reproducibility of its performance in both of the experimental settings. Statistical data analysis was conducted to determine any differences in performance of the Fire-Eye device among each laboratory-scale methods as well as to compare the performance of the device between laboratory-scale and full-scale fire environments in identical heat locations. The results suggest that a dual approach (laboratory-scale and full-scale fire environment) for evaluating the performance of PPES is more effective than is testing the device in either one of the methods.Ph. D.
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Schwicht, Daniel Ethan. "Large-Scale Strength Testing of High-Speed Railway Bridge Embankments: Effects of Cement Treatment and Skew Under Passive Loading." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7346.
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To investigate the passive force-displacement relationships provided by a transitional zoned backfill consisting of cement treated aggregate (CTA) and compacted gravel, a series of full-scale lateral abutment load tests were performed. The transitional zoned backfill was designed to minimize differential settlement adjacent to bridge abutments for the California High Speed Rail project. Tests were performed with a 2-D or plane strain backfill geometry to simulate a wide abutment. To investigate the effect of skew angle on the passive force, lateral abutment load tests were also performed with a simulated abutment with skew angles of 30º and 45º. The peak passive force developed was about 2.5 times higher than that predicted with the California HSR design method for granular backfill material with a comparable backwall height and width. The displacement required to develop the peak passive force decreased with skew angle and was somewhat less than for conventional granular backfills. Peak passive force developed with displacements of 3 to 1.8% of the wall height, H in comparison to 3 to 5% of H for conventional granular backfills.The skew angle had less effect on the peak passive force for the transitional backfill than for conventional granular backfills. For example, the passive force reduction factor, Rskew, was only 0.83 and 0.51 for the 30º and 45º skew abutments in comparison to 0.51 and 0.37 for conventional granular backfills. Field measurements suggest that the CTA backfill largely moves with the abutment and does not experience significant heave while shear failure and heaving largely occurs in the granular backfill behind the CTA backfill zone.
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Ruffley, Daniel J. "A Finite Element Approach for Modeling Bolted Top-and-Seat Angle Components and Moment Connections." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1304448809.
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Yuan, Hao. "Optimization of Rib-To-Deck Welds for Steel Orthotropic Bridge Decks." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/35935.
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Orthotropic steel deck has been widely used over the decades especially on long-span bridges due to its light weight and fast construction. However fatigue cracking problems on the welds have been observed in many countries. Rib-to-deck welds need special care since they are directly under wheel loads, which cause large local stress variations and stress reversals.
Currently the only requirement by AASHTO bridge code is that the rib-to-deck welds need to be fabricated as one-sided partial penetration welds with minimum penetration of 80% into the rib wall thickness. However considering the thin rib plate thickness, it is very difficult to achieve this penetration without a â melt-throughâ or â blow-throughâ defect. Large cost has been caused for the repair. However recent research has found that the fatigue performance of the rib-to-deck weld is not directly related to its penetration. Other factors contribute to the fatigue performance as well. Therefore, alternative requirements which are more cost-effective and rational are desired.
The objective of this research is to provide recommendations to the design and fabrication of rib-to-deck welds by investigating their fatigue performance with different weld dimensions, penetrations, and welding processes. Fatigue tests were performed to 95 full-scale single-rib deck segments in 8 specimen series fabricated with different welding processes and root gap openness. Specimens were tested under cyclic loads till failure. Three failure modes were observed on both weld toes and the weld root. Test results showed that the fatigue performance was more affected by other factors such as failure mode, R-ratio and root gap openness, rather than the weld penetration. The failure cycles were recorded for the following S-N curve analysis.
Finite element analysis was performed to determine the stress state on the fatigue cracking locations. Special considerations were made for the application of hot-spot stress methodology, which post-processes the FEA results to calculate the stress values at cracking locations with the structural configuration taken into account. The hot-spot stress range values were derived and adjusted accounting for the fabrication and test error. Hot-spot S-N curves were established for each specimen series.
Statistical analyses were performed to study in depth the effect of weld dimensions and test scenarios. Multiple linear regression (MLR) was performed to investigate the effects of different weld dimensions; and multi-way analysis of covariance (Multi-way ANCOVA) for the effects of specimen series, failure mode, R-ratio and weld root gap. It was found that the weld toe size was more relevant to the fatigue performance, other than the weld penetration. The failure mode and R-ratio were very influential on the fatigue performance. Recommendations to the weld geometry were proposed based on the MLR model fitting. S-N data were re-categorized based on ANCOVA results and the lower-bound S-N curve was established. AASHTO C curve was recommended for the deck design.
Master of Science
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Ghasabeh, Mehran. "Bond Of Lap-spliced Bars In Self-compacting Concrete." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615530/index.pdf.
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Self-compacting concrete is an innovative construction materialits priority to normal vibrated concrete is that there is not any vibration requirement. Bond strength of reinforcement is one of the key factors that ensures the usefulness of any reinforced concrete structure. In this study, 6 full-scale concrete beams spliced at the mid-span were tested under two-point symmetrical loading. Test variables were bottom cover, side cover, free spacing between longitudinal reinforcement, lap-splice length and presence of transverse reinforcements within the lap-splice region. Specimen SC_22_44_88_800 had cover dimensions close to the code limits and had 36db lap splice length. This specimen showed flexural failure. Specimen SC_44_44_44_710 had 32db lap splice and cover dimensions greater than code minimums. This specimen showed yielding primarily. With the increasing loading, however, bond failure occurred with side splitting. ACI 408 descriptive equation for normal vibrated concrete predicted bar stresses of the unconfined specimens produced with self-compacting concrete acceptably well. The predicted values were lower than the measured values to be on the safe side. The error varied between 3.4% and 6.5%. All predictions of the ACI408 descriptive equation was higher than the measured bar stresses of the confined specimens produced with SCC. All the calculated values were unsafe. The error varied between 10.6% and 34.5%. Specimen SC_44_22_22_530_T4 with 24db lap splice length had side cover and spacing between bars 63.3% and 56.7% less than the ACI 318 limits. The calculated bar stress was 21.6% higher than the measured value. The main reason of the deviation was inadequate cover dimensions. In specimen SC_44_22_22_530_T6, number transverse reinforcement was increased to 6 stirrups to overcome the small cover and spacing problem. However, increased number of stirrups inside a small side and face cover caused weak plane and measured bar stress decreased.
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Li, Kai. "Collapse Experiments and Assessment of Masonry Wall Buildings." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503265342241364.
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Kristiansson, Anders. "Evaluation of a concrete plug : From the Dome Plug Experiment DOMPLU at Äspö HRL." Thesis, KTH, Betongbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147503.
Full textAbstract:
In SKB’s Äspö Hard Rock Laboratory (HRL) a full scale test of a concrete plug,part of a sealing structure for the depository of spent nuclear fuel, has been carriedout. The aim of this thesis is to evaluate the behavior of the concrete plug and howit corresponds to assumptions made during the design. The concrete plug is domeshaped, un-reinforced and casted in situ with low-pH concrete. It will be exposed tohigh water and swelling pressures and designed for a life span of 100 years. Duringthe first years it shall also prevent water leakage from the inside of the depositiontunnel. Before the pressure is applied, the concrete plug is assumed to de-bond fromthe rock due to autogenous and cooling shrinkage. The gap between the concrete androck is then grouted during cooling and the concrete plug will hence be prestressedwhen the cooling is stopped. The concrete plug is analyzed with the measurement data from the full scale testwith comparisons to results from finite element simulations. The performed measurementsinclude form pressure, internal strain and temperature, concrete plugdisplacements in the tunnel alignment, displacements relative to the rock and ambienttemperatures. Two assumptions have been made during the evaluation; fullbond to the rock or no bond to the rock. The results are also compared to twosimilar experiment that were previously performed. The results indicate that the concrete did de-bond from the rock before grouting tosome extent. It is plausible that a selective de-bonding was obtained. Due to highwater leakage, were cables for the measurement equipment are drawn out from theconcrete plug, the concrete plug was not exposed to the planed maximum pressureload. Results indicate that a water pressure is acting on the concrete plug frominside the rock slot which was not assumed during the design.I SKB:s Äspölaboratoriet har ett fullskaleförsök på en betongplugg, del av ett pluggsystemför förvaret av kärnavfall, utförts. Syftet med denna uppsats var attutvärdera betongpluggens beteende under fullskaleförsöket och hur det förhållersig till gjorda antaganden under dess utformning. Betongpluggen är kupolformad,oarmerad och platsgjuten med låg-pH-betong. Höga vatten- och svälltryck kommerverka på betongpluggen som är utformad för en livstid på 100 år. Under deförsta åren ska den även motverka läckage från insidan av deponeringstunneln. Innantrycklasten läggs på är det antaget att betongpluggen släpper från berget till följd avautogen krympning och kylning. Utrymmet mellan betongen och berget injekterasoch betongpluggen kommer således vara förspänd efter att kylningen upphört. Betongpluggen är analyserad med mätdata från fullskaleförsöket som jämförts medresultat från finita element analyser. Mätningarna inkluderar formtryck, inre töjningaroch temperaturer, deformationer i tunnelriktningen, deformationer relativt bergetoch lufttemperatur utanför betongpluggen. Två antaganden har gjorts under utvärderingen;att betongen är fast i berget eller att den är fri från berget. Resultaten jämförsäven med två liknande fullskaleförsök som utförts tidigare. Resultaten tyder på att betongpluggen till viss del släppt från berget innan injekteringen.Det är troligt att den släppt på vissa ställen och på andra inte. På grundav för högt vattenläckage där de ingjutna mätinstrumentens kabelgenomföring utförts,kunde inte betongpluggen belastas till det maximala tryck som var planerat.Resultaten tyder på att ett vattentryck verkar på betongpluggen mellan berget ochbetongen vilket inte var antaget under konstruktionen.
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Corneille, Sébastien. "Étude du comportement mécanique des colonnes ballastées chargées par des semelles rigides." Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL036N/document.
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Les inclusions souples, telles que les colonnes ballastées, sont constituées de matériaux granulaires purement frottants et réalisées à partir de différentes méthodes, afin d’entraîner des améliorations des performances du sol (réduction des tassements, augmentation de la capacité portante, etc.). Dès leur origine, fin des années 1950, ces colonnes ont été employées en maillages réguliers sous des ouvrages de grandes dimensions (remblais, réservoirs, dallages…) apportant des surcharges uniformément réparties. Depuis plusieurs années, les colonnes sont souvent mises en œuvre de manière isolée ou en groupe d’éléments limités (2 à 6 unités) et coiffées par une semelle rigide. Il est donc important de prévoir le comportement mécanique de ces inclusions sous des semelles rigides compte tenu de leur application à de nombreuses structures (logements, bâtiments industriels…). L’objectif principal du travail présenté ici est : (1) d’analyser et de quantifier l’amélioration du sol obtenue par la mise en place des colonnes ballastées, dans un sol argileux, sous semelles rigides et (2) de développer une méthodologie numérique permettant de valider les résultats d’essais en grandeur réelle. Pour atteindre ces objectifs, une importante campagne d’essais en grandeur réelle a été élaborée puis mise en œuvre. Il s’agit d’une campagne de sondages de pénétration statique réalisés avant et après la mise en place des colonnes (isolées ou en groupe de 3 de 1,8 m d’entre-axe), ainsi que d’essais de chargement comparatifs en grandeur réelle pendant 77 jours, de semelles (1,2 x 1,2 x 0,5 m) sur une colonne ballastée et sur le sol naturel, et de semelles (2,3 x 2,5 x 0,5 m) sur trois colonnes et sur le sol naturel. Une importante instrumentation du sol et des colonnes (inclinomètres, sondes de pression interstitielle, capteurs de pression totale verticale) a été mise en place avant la réalisation des colonnes afin de déterminer l’amélioration du sol et le comportement à la rupture de ces inclusions. Puis, les résultats expérimentaux (déplacements horizontaux et verticaux, et contraintes totales verticales) ont été confrontés aux résultats de modélisations numériques en 2 (PLAXIS 2D V8) et 3D (FLAC 3D). Ont notamment été étudiés en 2D les outils numériques permettant de simuler le processus de mise en œuvre d’une colonne par refoulement latéral du solFlexible inclusions, such as stone columns, are made up of purely frictional granular material and are constructed using a variety of methods, in order to improve the soil (settlement reduction, increase in bearing capacity…). At their beginning, end of the 1950’s, stone columns were placed in a regular mesh under great structures (embankments, tanks, slabs…) bringing uniformly distributed loads. Since several years, these columns are often constructed as isolated elements or in groups of a certain number (generally 2 to 6) on top of which is placed a rigid footing. It is thus important to predict the stone column’s mechanical behavior under rigid footings knowing that they can be used under a broad variety of structures (accomodation, industrial buildings…). The main purpose of the work presented in this thesis is to: (1) analyse and quantify the soil’s improvement thanks to the construction of stone columns, in a clayey soil, under rigid footings and (2) to develop a numerical methodology allowing us to validate full scale experimental results. In order to achieve this, an important full scale load test campaign was first conceived and then set up. Cone penetration tests were carried out before and after stone column construction (in isolated elements or in groups of three columns located at the corners of a 1,8 m faced triangle). Another part of this campaign deals with comparative full scale load tests carried out during 77 days: two rigid footings of 1.2 x 1.2 x 0.5 m, one on the natural soil and one placed on top of a stone column, and two rigid footings of 2.3 x 2.5 x 0.5 m, one on the natural soil and the other one placed on three stone columns. An important soil and column monitoring (inclinometers, pore pressure cells, total vertical load pressure cells) was set up before column construction in order to measure the soil’s improvement and the column’s failure behavior. The the experimental results (lateral and vertical displacements, and total vertical pressures) were compared to numerical ones in 2 (PLAXIS 2D V8) and 3D (FLAC 3D). In 2D, part of the work was focused on simulating the installation process of a stone column by lateral displacement of the soil
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Bustamante, Guillermo. "Influence of Pile Shape on Resistance to Lateral Loading." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5630.
Full textAbstract:
The lateral resistance of pile foundations has typically been based on the resistance of circular pipe piles. In addition, most instrumented lateral load tests and cases history have involved circular piles. However, piles used in engineering practice may also be non-circular cross-section piles such as square and H piles. Some researchers have theorized that the lateral resistance of square piles will be higher than that of circular piles (Reese and Van Impe, 2001; Briaud et al, 1983; Smith, 1987) for various reasons, but there is not test data to support this claims. To provide basic comparative performance data, lateral load tests were performed on piles with circular, square and H sections. To facilitate comparisons, all the tests piles were approximately 12 inches in width or diameter and were made of steel. The square and circular pipe sections had comparable moments of inertia; however, the H pile was loaded about the weak axis, as is often the case of piles supporting integral abutments, and had a much lower moment of inertia. The granular fill around the pile was compacted to approximately 95% of the standard Proctor maximum density and would be typical of fill for a bridge abutment. Lateral load was applied with a free-head condition at a height of 1 ft above the ground surface. To define the load-deflection response, load was applied incrementally to produce deflection increments of about 0.25 inches up to a maximum deflection of about 3 inches. Although the square and pipe pile sections had nearly the same moment of inertia, the square pile provided lateral resistance that was 20 to 30% higher for a given deflection. The lateral resistance of the H pile was smaller than the other two pile shapes but higher than what it is expected based on the moment of inertia. Back analysis with the computer program LPILE indicates that the pile shape was influencing the lateral resistance. Increasing the effective width to account for the shape effect as suggested by Reese and Van Impe (2001) was insufficient to account for the increased resistance. To provide agreement with the measured response, p-multipliers of 1.2 and 1.35 were required for the square pile and H piles, respectively. The analyses suggest that the increased resistance for the square and H pile sections was a result of increases in both the side shear and normal stress components of resistance. Using the back-calculated p-multipliers provided very good agreement between the measured and computed load-deflection curves and the bending moment versus depth curves.
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Russell, Dalin Newell. "The Influence of Pile Shape and Pile Sleeves on Lateral Load Resistance." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6232.
Full textAbstract:
The lateral resistance of pile foundations is typically based on the performance of round piles even though other pile types are used. Due to lack of data there is a certain level of uncertainty when designing pile foundations other than round piles for lateral loading. Theoretical analyses have suggested that square sections will have more lateral resistance due to the increased side shear resistance, no test results have been available to substantiate the contention. Full-scale lateral load tests involving pile shapes such as circular, circular wrapped with high density polyethylene sheeting, square, H, and circular with a corrugated metal sleeve have been performed considering the influence of soil-pile interaction on lateral load resistance. The load test results, which can be summarized as a p-y curve, show higher soil resistance from the H and square sections after accounting for differences in the moment of inertia for the different pile sections. The increased soil resistance can generally be accounted for using a p-multiplier approach with a value of approximately 1.25 for square or 1.2 for H piles relative to circular piles. It has been determined that high density polyethylene sheeting provides little if any reduction in the lateral resistance when wrapped around a circular pile. Circular piles with a corrugated metal sleeve respond to lateral loading with higher values of lateral resistance than independent circular piles in the same soil.
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Kaabia, Bassem. "Méthodes avancées d'évaluation des charges de vent sur les structures de concentrateurs solaires." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11315.
Full textAbstract:
L’énergie solaire photovoltaïque concentré (CPV) est une solution de remplacement prometteuse aux structures solaires conventionnelles. Ce type de structure modulable doit être optimisé afin d’être compétitif par rapport aux autres types de production d’énergie. Les forces de vent demeurent la première préoccupation dans la conception de la structure porteuse en acier d’un tel système. L’objectif principal de cette recherche est d’assembler des outils numériques et analytiques afin de prédire les caractéristiques de sa réponse dynamique sous charges de vent turbulent. La maîtrise de cette étape est essentielle afin d’étudier d’une façon plus générique des solutions d’optimisation de la structure support par rapport à sa réponse dynamique sous charges de vent. Pour ce faire, la méthodologie principale de cette étude est composée en trois parties : (i) étude expérimentale à grandeur nature de la réponse globale sous les conditions réelles du vent ; (ii) développement des modèles d’analyse numérique dans lesquels les caractéristiques de structures réelles et des
modèles de forces aérodynamiques adéquates sont prises en compte ; (iii) application des outils développés dans une étude paramétrique pour évaluer plusieurs solutions à partir de cas d’étude dans le contexte d’une conception préliminaire.
Cette thèse est présentée sous forme de deux articles qui ont été soumis dans des revues évaluées par des comités de lecture ainsi que d’un article soumis et présenté dans un congrès international qui démontrent les contributions de cette recherche pour améliorer les pratiques de calcul des charges de vent sur des structures de concentration solaire non conventionnelles. Ces articles sont présentés comme suit (a) Étude expérimentale à échelle réelle de la réponse d’un prototype de concentrateur solaire sous charges de vent. Ce premier article a permis la validation de calcul des coefficients de forces aérodynamiques statiques et la révision des hypothèses de l’application du code ASCE 7-10 pour prédire les forces maximales agissant sur la structure dans la direction du vent ; (b) l’analyse temporelle
de la réponse dynamique d’une structure de concentrateur solaire sous charges de
vent. Cette étude a montré que le modèle et la méthode d’analyse développés selon des hypothèses simplifiées permettaient de prédire correctement les caractéristiques statistiques de la réponse dynamique mesurée en cohérence avec la méthode spectrale stochastique ; (c) Étude des effets des configurations structurales et des paramètres de vent sur l’optimisation de structure solaires sous charges de vent. Cette étude paramétrique a mis en évidence l’importance de l’effet des paramètres structuraux et ceux définissant le vent sur l’optimisation de la conception structural pour ce type de structure. Des recommandations pour optimiser l’action dynamique dans une phase de conception préliminaire ont été proposées. Ce projet de recherche a démontré finalement l’importance d’étudier d’une façon juste et pratique la réponse dynamique sous charges de vent qui mène à résoudre des préoccupations d’optimisation liées à différents types de structures d’énergie solaire en adoptant des hypothèses pratiques pour les ingénieurs.Abstract : Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar structures. These solar traking structures need to be optimized to be competitive against other types of energy production. Wind action is the main concern in the design of the steel support structure of such movable system. The main purpose of this research is to assemble advanced numerical and analytical tools that allows realistic dynamic study of structures under wind loading. This help to study accurately optimized alternative in term of selecting structural and wind site conditions parameters. The methodology of the present study involves three main steps : (i) experimental full-scale study of the global response under real life wind conditions ; (ii) numerical modeling that captures the characteristics of the real structures and include the aerodynamic force models to conduct time-domain dynamic analyses ; (iii) preliminary design application that include the study of the effect of stuctural and wind parameters in optimizing the dynamic wind action and consequently the steel support structure. The thesis is presented as an ensemble of three articles written for refereed journals and a conference that showcase the contributions of the present study to thoroughly understand the wind load effect on these nonconventionnel structures. The articles presented are as follow (a) full-scale measurement of the response of a CPV tracker structure prototype under wind load. The results presented in this first article help design engineers to evaluate the use of the aerodynamic force coefficients for calculating wind load on similar structures and to apply properly the ASCE7-10 in evaluating the maximum design wind force using the equivalent static approach ; (b) time-domain analysis of solar concentrator structure under gust wind. This study showed that the developed time-domain model using simplified hypothesis could successfully predict the statistical parameters of the measured dynamic response in coherence with the stochastic spectral approach ; (c) effect of structure configurations and wind characteristics on the design of solar concentrator support structure under dynamic wind action. This parametric study highlighted the importance of selecting structural and wind parameters in order to minimize the dynamic action and the steel support structure. Recommendations for optimizing dynamic wind action in a preliminary design phase were proposed. The present research project has shown the need to study accurately wind response to solve optimization concerns related to different type of solar system structures. In addition, this study proposes simplified methods that are useful for practical engineers when there is the need to solve similar problems.
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Bagge, Niklas. "Structural assessment procedures for existing concrete bridges : Experiences from failure tests of the Kiruna Bridge." Doctoral thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63000.
Full textAbstract:
Assessing existing bridges is an important task in the sustainable management ofinfrastructure. In practice, structural bridge assessments are usually conducted usingtraditional and standardised methods, despite knowledge that these methods oftenprovide conservative estimates. In addition, more advanced methods are available, suchas nonlinear finite element (FE) analysis, that are used for research purposes and cansimulate the structural behaviour of bridges more accurately. Therefore, it would beuseful to develop practical and reliable procedures for refined assessments using theseadvanced techniques.Focusing on the ultimate load-carrying capacity of existing concrete bridges, this thesispresents a procedure for structural assessments. The fundamental idea is to improve theassessment successively, as necessary to predict bridges’ structural behaviour adequately.The procedure involves a multi-level assessment strategy with four levels of structuralanalysis, and an integrated framework for safety verification. At the initial level (Level 1)of the multi-level strategy, traditional standardised methods are used, no failures arecovered implicitly in the structural analysis and action effects are verified using localresistances calculated using analytical models. In the subsequent enhanced levels (Levels2 – 4), nonlinear FE analysis is used for stepwise integration of the verification of flexural,shear-related and anchorage failures into the structural analysis. The framework for safetyverifications includes partial safety factor (PSF), global resistance safety factor (GRSF) andfull probabilistic methods. Within each of these groups, verifications of desired safetymargins can be conducted with varying degrees of complexity.To demonstrate and evaluate the proposed structural assessment procedure, comparativestudies have been carried out, based on full-scale tests of a prestressed concrete bridge.This was the Kiruna Bridge, located in the northernmost city in Sweden, which was duefor demolition as part of a city transformation project, necessitated by large grounddeformations caused by the large nearby mine. Thus, it was available for destructiveexperimental investigation within the doctoral project presented in this thesis. The bridgehad five continuous spans, was 121.5 m long and consisted of three parallel girders with a connecting slab at the top. Both the girders and slab were tested to failure to investigatetheir structural behaviour and load-carrying capacity. Non-destructive and destructivetests were also applied to determine the residual prestress forces in the bridge girders andinvestigate the in situ applicability of methods developed for this purpose. The so-calledsaw-cut method and decompression-load method were used after refinement to enabletheir application to structures of such complexity. The variation of the experimentallydetermined residual prestress forces was remarkably high, depending on the sectioninvestigated. There were also high degrees of uncertainty in estimated values, and thusare only regarded as indications of the residual prestress force.Level 1 analysis of the multi-level assessment strategy consistently underestimatedcapacity, relative to the test results, and did not provide accurate predictions of the shearrelatedfailure observed in the test. With linear FE analysis and local resistance modelsdefined by the European standard, Eurocode 2, the load-carrying capacity wasunderestimated by 32 % for the bridge girder and 55 % for the bridge deck slab. At theenhanced level of structural analysis (Level 3), nonlinear FE analyses predicted thecapacities with less than 2 % deviation from the test results and correctly predicted thefailure mode. However, for existing bridges there are many uncertainties, for instance,the FE simulations were sensitive to the level of residual prestressing, boundaryconditions and assumed material parameters. To accurately take these aspects intoaccount, bridge-specific information is crucial.The complete structural assessment procedure, combining the multi-level strategy andsafety verification framework, was evaluated in a case study. Experiences from theprevious comparative studies were used in an assessment of the Kiruna Bridge followingthe Swedish assessment code. The initial assessment at Level 1 of the multi-level strategyand safety verification, using the PSF method, indicated that the shear capacity of one ofthe girders was critical. The most adverse load case (a combination of permanent loads,prestressing and variable traffic loads) was further investigated through enhancedstructural analyses implicitly accounting for flexural and shear-related failures (Level 3).Nonlinear FE analysis and safety evaluation using the PSF method, several variants of theGRSF method and the full probabilistic analysis for resistance indicated that the permittedaxle load for the critical classification vehicle could be 5.6 – 6.5 times higher than thelimit obtained from the initial assessment at Level 1. However, the study also indicatedthat the model uncertainty was not fully considered in these values. The modeluncertainty was shown to have strong effects on the safety verification and (thus)permissible axle loads. The case study also highlighted the need for a strategy forsuccessively improving structural analysis to improve understanding of bridges’ structuralbehaviour. The refined analysis indicated a complex failure mode, with yielding of thestirrups in the bridge girders and transverse flexural reinforcement in the bridge deck slab,but with a final shear failure of the slab. It would be impossible to capture suchcomplexity in a traditional standardised assessment, which (as mentioned) indicated thatthe shear capacity of the girder limited permissible axle loads. However, nonlinear FEanalyses are computationally demanding, and numerous modelling choices are required.Besides a strategy for rationally improving the analysis and helping analysts to focus oncritical aspects, detailed guidelines for nonlinear FE analysis should be applied to reduce the analyst-dependent variability of results and (thus) the model uncertainty. Clearly, toensure the validity of bridge assessment methods under in situ conditions, theirevaluations should include in situ tests. This thesis presents outcomes of such tests, therebyhighlighting important aspects for future improvements in the assessment of existingbridges.
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Nepovím, Radovan. "Konstrukce experimentálního zařízení pro studium mazání okolků kolejových vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230331.
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The diploma thesis deals with construction design and practical realisation of experimental apparatus for investigation of wheel flange track vehicle lubrication. Experimental apparatus in full-scale uses optical interferometry for investigation of lubrication behaviour in wheel flange contact. It is an innovative approach which has not been used for such experiments so far. The aim of the following measurement with this apparatus is to determine the minimal amount of ecological lubrication in wheel flange contact under certain conditions when there is no lubrication film interruption. The apparatus enables to measure real rail wear. This work contains the apparatus description for the study of wheel flange lubrication, wheel flange contact specifications, the description of its influence on wear and acoustic emission, and a detailed description of the experimental apparatus.