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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Performance analysis software for reinforced concrete beam-columns under various load and displacement patterns

Rohleder, Schyler January 1900 (has links)
Master of Science / Department of Civil Engineering / Asad Esmaeily / Performance-based building design is a necessity in geographic locations where buildings are susceptible to large earthquakes and high winds. This design method requires an analysis of the performance of the structural system with loadings and deflections caused by earthquakes and wind. Current design codes include the load intensity in analysis procedures, but do not consider the effect of load pattern in the performance analysis of reinforced concrete columns. Because a thorough analysis must take into consideration load pattern and load intensity, computer software is ideal to analyze these systems. A computer program was originally developed by Esmaeily (USC_RC), and was revised later to be renamed (KSU_RC) in order to make the analysis of concrete column performance accurate, yet simple for design purposes. This analytical tool used analytical methods and material models, verified against experimental data, to accurately predict the performance of reinforced concrete columns under various loading conditions, including any pattern in lateral direction and independently variable axial load. However, the program was limited to circular, rectangular, hollow circular and rectangular sections and uniaxial lateral curvature and displacement. The next generation of the program, KSU RC 2.0, was developed to overcome the aforesaid limitations.
2

Verschiebungsmuster in Böschungen während Aushubvorgängen / Displacement patterns in slopes during excavation processes

Nitzsche, Kornelia 06 December 2016 (has links) (PDF)
After the excavation of a cut slope ongoing deformations on the slope surface can often be measured. These deformations can be induced due to various processes and can also be used as an indicator of slope stability. If the reasons for the deformations are known, selective stabilization methods can help to decelerate, or stop, the movements. The potential for the recognition of displacement patterns in excavated slopes is studied in this dissertation. In the laboratory, the analysis of displacement patterns due to various processes is difficult as identical initial test conditions can hardly be reproduced. Furthermore, measurements of displacements can only be conducted to a limited degree. Therefore, numerical calculations using the finite element method were applied to simulate excavation processes and analyse the displacements. In addition, a suitable mathematical model has to be used to represent the stress-strain behaviour during the unloading process. Three different advanced constitutive soil models were chosen to calculate an excavation process of an idealized slope assuming drained conditions: - elasto-plastic Modified-Cam-Clay model - rate-independent hypoplastic model according to Masin - rate-dependent visco-hypoplastic model according to Niemunis Before conducting the excavation simulation, the soil parameters of the constitutive models were calibrated by means of numerical element tests, depicting the stress paths of conventional laboratory tests. Within the literature, those conventional laboratory tests are recommended for the determination of parameters for the constitutive models. A parameter set for the visco-hypoplastic model was chosen from literature. The parameters were adapted for the remaining models. Thus, all three models predicted approximately the same stress-strain behaviour during conventional laboratory tests. Despite the correlations during the element tests, the constitutive models predicted different displacements during the calculation of the excavation of an idealized slope under drained conditions. Thereupon, load-controlled triaxial compression tests were conducted reproducing the characteristic stress paths during an excavation process. At the same time, numerical calculations were carried out to reproduce the triaxial compression tests, and the measured and calculated displacement behaviour was compared. Different processes such as pure unloading due to excavation, excavation in overconsolidated soil, excavation coupled with consolidation, excavation coupled with previous ground water lowering and consolidation as well as the influence of creep effects were considered in the analysis of the displacement patterns during an excavation. It can be stated that the evaluation of displacements and changes in displacements in a single point on the slope surface cannot provide sufficient information about a certain physical process. Only the combination of displacement paths at different survey points will lead to a reliable conclusion. Thus, representative displacement patterns for different processes are recognizable during and after the excavation, which can be used for the identification. During the numerical simulation of an in-situ model test, where a slope was brought to failure by excavation, the calculated displacements were analysed for identifiable displacement patterns. It can be stated that despite different slope systems, consistencies were found within characteristic survey points. These points can be used to identify patterns within the displacement contours.
3

Verschiebungsmuster in Böschungen während Aushubvorgängen

Nitzsche, Kornelia 06 December 2016 (has links)
After the excavation of a cut slope ongoing deformations on the slope surface can often be measured. These deformations can be induced due to various processes and can also be used as an indicator of slope stability. If the reasons for the deformations are known, selective stabilization methods can help to decelerate, or stop, the movements. The potential for the recognition of displacement patterns in excavated slopes is studied in this dissertation. In the laboratory, the analysis of displacement patterns due to various processes is difficult as identical initial test conditions can hardly be reproduced. Furthermore, measurements of displacements can only be conducted to a limited degree. Therefore, numerical calculations using the finite element method were applied to simulate excavation processes and analyse the displacements. In addition, a suitable mathematical model has to be used to represent the stress-strain behaviour during the unloading process. Three different advanced constitutive soil models were chosen to calculate an excavation process of an idealized slope assuming drained conditions: - elasto-plastic Modified-Cam-Clay model - rate-independent hypoplastic model according to Masin - rate-dependent visco-hypoplastic model according to Niemunis Before conducting the excavation simulation, the soil parameters of the constitutive models were calibrated by means of numerical element tests, depicting the stress paths of conventional laboratory tests. Within the literature, those conventional laboratory tests are recommended for the determination of parameters for the constitutive models. A parameter set for the visco-hypoplastic model was chosen from literature. The parameters were adapted for the remaining models. Thus, all three models predicted approximately the same stress-strain behaviour during conventional laboratory tests. Despite the correlations during the element tests, the constitutive models predicted different displacements during the calculation of the excavation of an idealized slope under drained conditions. Thereupon, load-controlled triaxial compression tests were conducted reproducing the characteristic stress paths during an excavation process. At the same time, numerical calculations were carried out to reproduce the triaxial compression tests, and the measured and calculated displacement behaviour was compared. Different processes such as pure unloading due to excavation, excavation in overconsolidated soil, excavation coupled with consolidation, excavation coupled with previous ground water lowering and consolidation as well as the influence of creep effects were considered in the analysis of the displacement patterns during an excavation. It can be stated that the evaluation of displacements and changes in displacements in a single point on the slope surface cannot provide sufficient information about a certain physical process. Only the combination of displacement paths at different survey points will lead to a reliable conclusion. Thus, representative displacement patterns for different processes are recognizable during and after the excavation, which can be used for the identification. During the numerical simulation of an in-situ model test, where a slope was brought to failure by excavation, the calculated displacements were analysed for identifiable displacement patterns. It can be stated that despite different slope systems, consistencies were found within characteristic survey points. These points can be used to identify patterns within the displacement contours.
4

Padrões de deslocamento de bovinos em pastos de capim-quicuio sob lotação intermitente / Displacement patterns of cattle grazing on kikuyu grass under rotational stocking

Rocha, Cintia Hoffer da 19 September 2014 (has links)
Made available in DSpace on 2016-12-08T16:24:20Z (GMT). No. of bitstreams: 1 PGCA14MA150.pdf: 671118 bytes, checksum: 044e392b9e087c5b498a3cdbdfdf9d62 (MD5) Previous issue date: 2014-09-19 / The sustainable management of pastures is in evidence in academic circles, looking for a better association between animal performance and natural resources conservation. The aim of this work was to evaluate cattle pattern displament on kikuiu-grass submitted to different heights and the same level of defoliation of 50%. The experiment was carried out at CAV/UDESC during April and May 2013. The experimental design was a complete randomized block design with three replications and four treatments. The treatments were four pre-grazing heights: 25, 20, 15 and 10 centimeters associated which were associated with a level of defoliation of 50%. Animals stand longer on feeding stations in 20 and 25 cm swards during the initial stage of grazing without differences on the final phase of grazings down. At the early stage, on the lower pasture height (10 cm) the animals walked more and moved more quickly when compared to those managed at higher swards heights (5,25 e 4,0, respectively). There was no difference during the final stage of grazings process. The bite number in each feeding station had a linear reduction with the increase in sward height during the initial phase, being minor on the 25 cm height (27 bites.feeding station-1), with no differences at the final stage. Bite rate (bites. min-1) also presented a linear response by reducing according the increase in pasture height, from 42,02 to 35,18 bites.min-1 in pastures with 10 and 25 cm, respectively. During the initial phase of the grazing down the animals presented diferences in displacement patterns, suggesting that swards heights of 20 to 25 cm (in kikuygrass) present better conditions to foraging search. At the final phase, the animals did not present differences among treatments, suggesting that on using 50% of the grazing down is already over the limit when the objective is to minimize forage searching / O manejo sustentável das pastagens está ganhando cada vez mais espaço na pesquisa mundial, visando maior desempenho animal aliado à preservação dos recursos naturais. O objetivo deste trabalho foi avaliar os padrões de deslocamento de bovinos em pastos de capim-quicuio, submetidos a diferentes alturas de entrada e mesma severidade de desfolhação de 50%. O experimento foi realizado no setor de bovinocultura leiteira do CAV/UDESC, durante os meses de abril e maio de 2013. O delineamento experimental foi em blocos completos casualizados com três repetições e quatro tratamentos. Os tratamentos eram quatro alturas em pré-pastejo: 25, 20, 15 e 10 cm, associados com uma severidade de desfolhação de 50% destas alturas. O maior tempo de permanência dos animais nas estações alimentares foi encontrado nos pastos mais altos, com 20 e 25 cm de altura, na fase inicial de rebaixamento dos pastos, sem diferenças na fase final do rebaixamento. Os animais caminharam mais (P.min-1) e com maior rapidez (passos entre estações) nos pastos mais baixos (10 cm), durante a fase inicial de rebaixamento destes. Já na fase final não foram observadas alterações. O número de bocados em cada estação alimentar na fase inicial do rebaixamento apresentou uma redução linear com o aumento da altura, sendo menor na altura de 25 cm (27,02), permanecendo sem diferenças na fase final. A taxa de bocados (bocados. min-1) também apresentou uma resposta linear, reduzindo conforme o aumento na altura dos pastos, de 42,02 para 35,18 bocados.min-1, nos pastos com 10 e 25cm, respectivamente. Os animais na fase inicial de rebaixamento dos pastos apresentaram diferenças nos padrões de deslocamento, indicando que alturas de dossel de 20 e 25 cm (em pastos de capim-quicuiu) apresentam melhores condições ao processo de forrageamento. Já na fase final, os animais não apresentaram diferenças entre os tratamentos, sugerindo que utilizando a faixa de 50% de rebaixamento dos pastos os animais já encontram dificuldades no processo de busca por forragem, independente de metas de alturas em pré-pastejo
5

Household Displacement after Hurricane Harvey: Decisions, Destination Choice, and Displacement Patterns

Sauceda, Miranda 07 1900 (has links)
The thesis examines post-event displacement of households in the year following Hurricane Harvey. Using data gathered from a three-page mail survey conducted approximately 1-year after the storm, this study examines two primary research objectives. First this thesis aims to identify variables that predict displacement or non-displacement after the disaster. Second, this study explores patterns in the destination and duration of displaced households following Hurricane Harvey. Logistic regression analyses were used to examine the extent to which household composition characteristics and level of damage sustained during Hurricane Harvey predicted post-disaster displacement. Next, independent sample t-tests and descriptive statistical analyses were used to identify patterns in the destination of post-event relocations. Research findings indicate in the overall binary logistic regression model that after Hurricane Harvey, being White, level of home damage, wind damage, and number of days a member of the household returned home post-Harvey increased the likelihood of a household being displaced. Analysis of the survey responses also indicated that many households made multiple moves following Hurricane Harvey and specifically, displaced households were more likely to stay with a friend or relative. Additionally, this study found that with each additional relocation, the duration of stay at each destination increased while the distance from their pre-disaster home decreased. This thesis advances understanding of what predicts household displacement after a disaster and offers new insights into where people go during the short-term and beginning of the long-term recovery phases.

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