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Undrained behavior of plate anchors subjected to general loadingYang, Ming 14 January 2010 (has links)
This study presents a method for predicting the undrained behavior of plate anchors, including out-of-plane loading of simple plates and performance of suction embedded plate anchors (SEPLA). Three dimensional finite element models are used to investigate the behavior of square and rectangular plate anchors under normal loading with eccentricity in any direction. Upper bound analyses are performed for parallel loading and torsion loading. A simple model is then fit to the FE and upper bound solutions to determine required fitting parameters for both square and rectangular plates. The simple models can, in turn, be used both to predict anchor capacity and as yield surfaces for conducting plastic limit analyses, a method capable of predicting post yield anchor trajectory. The model predictions are shown in reasonable good agreement with the experimental results. For SEPLA, a theoretical model of plastic limit analysis is developed to predict the trajectory during the “keying” process and the ultimate capacity after the “keying” is complete. The predicted results are consistent with relevant known solutions.
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Undrained behavior of plate anchors subjected to general loadingYang, Ming 14 January 2010 (has links)
This study presents a method for predicting the undrained behavior of plate anchors, including out-of-plane loading of simple plates and performance of suction embedded plate anchors (SEPLA). Three dimensional finite element models are used to investigate the behavior of square and rectangular plate anchors under normal loading with eccentricity in any direction. Upper bound analyses are performed for parallel loading and torsion loading. A simple model is then fit to the FE and upper bound solutions to determine required fitting parameters for both square and rectangular plates. The simple models can, in turn, be used both to predict anchor capacity and as yield surfaces for conducting plastic limit analyses, a method capable of predicting post yield anchor trajectory. The model predictions are shown in reasonable good agreement with the experimental results. For SEPLA, a theoretical model of plastic limit analysis is developed to predict the trajectory during the “keying” process and the ultimate capacity after the “keying” is complete. The predicted results are consistent with relevant known solutions.
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Finite Element Analysis Of Laboratory Model Experiments On Behavior Of Shallow Foundations Under General LoadingOktay, Emre Hasan 01 February 2012 (has links) (PDF)
In this study, a series of laboratory model experiments carried on shallow foundations is intended to be simulated through numerical modeling. The laboratory model tests were conducted by Fukui et al. (2005), over square shaped, shallow surfacial foundations located over air-dried Toyoura sand. Tests included centered vertical and combined loading cases on sand with 60% and 80% relative densities. Plastic limit loads obtained from numerical analyses and available analytical solutions in literature are compared to the laboratory test results and the differences are discussed.
Employment of Mohr - Coulomb yield criterion and linear elasticity, resulting in linear elastic perfectly plastic constitutive law, is one of the most common practices in modeling geotechnical problems. Accuracy of this approach for the modeled experiments is judged by comparison of analyses results with experimental findings and solutions in literature. Finite element method is utilized for modeling purposes, with Mohr-Coulomb yield criterion and linear elastic behavior. Abaqus 6-10.2 is selected as the analysis software, and two and three dimensional models are used in the analyses. Analyses, the results of which are compared with experimental findings, aim employment of associated flow rule. Additional analyses are conducted with varying dilation angles in order to examine the influence of unassociated flow rule on eccentric and concentric loading results.
Differences between the results of numerical analyses and experimental observations varied between 2% and 34%. Main reason of the difference is attributed to employed soil behavior modeling approach in analyses and the eccentric placement of model weight in monotonic horizontal loading experiments. In the case when this eccentric placement is accounted for in numerical models, it is seen that the difference diminished to vary between 8% and 18%, and order of the difference was similar for similar experiment cases. Therefore, based on this condition, it is seen that results of the modeled experiments are consistent, while in general they are somewhat higher than the results obtained from analyses and solutions in literature. Difference between the results of analyses and average of selected solutions in literature in both cases is at most 9%.
Finite element method employing Mohr-Coulomb failure criterion could provide results in close agreement with solutions in literature that inherently assume Mohr-Coulomb failure criterion as well. However, the same accuracy could not be obtained for experiments due to uncertainties involved in the material properties as well as the insufficiencies of the model to represent the behavior precisely. Finite element method has the potential to consider more advanced material models. Nonetheless, employment of Mohr-Coulomb failure criterion provides results with sufficient accuracy for most cases.
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