Pile-supported T-walls, which are concrete floodwalls that are shaped like an inverted "T" and supported by batter piles, are commonly used by the United States Army Corps of Engineers (USACE) to protect low-lying portions of New Orleans and other areas. The design of a T-wall in southern Louisiana is complex, as the structure needs to resist both 1) large settlements caused by fill placed beneath and beside the T-wall before T-wall construction or by fill placed beside the T-wall after T-wall construction, and 2) large lateral flood loads that are imposed during a hurricane. As a result of these loading conditions, large bending moments can develop in the batter piles and these moments need to be accounted for as part of the T wall design. The goal of this research is to develop a more complete understanding of the pile bending moments in T wall systems, specifically for cross sections where large settlements may occur. As a first step towards this goal, Rensselaer Polytechnic Institute (RPI) performed a series of eight centrifuge tests to investigate and physically model the effects of settlement-induced bending moments on pile-supported T-walls. The centrifuge tests were evaluated and interpreted, and in order to better capture uncertainty, upper and lower bounds were estimated for the interpreted data. The centrifuge results offered some valuable insights on their own, but were ultimately used as the basis for validating and calibrating corresponding numerical models. The numerical models were developed following a rigorous modeling approach and using rational and reasonable assumptions based on widely-accepted and well-justified procedures. The numerical model results were in good agreement with the centrifuge results without the need for significant calibration or modifications. This good agreement indicates that similar numerical models can be developed to reliably analyze actual T-wall cross sections. Detailed recommendations were developed for using numerical models to analyze pile-supported T walls, and an example problem is presented herein that illustrates the application of this approach. These same techniques were then used to perform a parametric study to analyze the combined and separate effects of flood loading for a wide range of different T-wall cross sections. The range was selected in collaboration with the USACE in order to reasonably cover cross sections and conditions that 1) are typically encountered in practice, and 2) were expected to generate both upper and lower bound pile bending moments. In total, 3,648 cross sections were analyzed, and 29,184 sets of analysis results were generated since each cross section was analyzed for eight different loading conditions. Summary results are provided to show the influence of the loading conditions and parameters on T-wall response, including the influence of flood loading, new fill symmetry, pile fixity, number of piles, subsurface profile, pile batter, pile type, levee slope, T-wall elevation, and the presence of existing levee fill. In addition, the key results for all of the analyses are provided in the appendices and in an electronic database. Based on the parametric study results, a simplified analysis procedure was developed that can be used to calculated maximum pile bending moments for T walls installed directly on foundation soils due to settlements. In this procedure, the loads from new fill placed during or after T-wall construction are distributed onto the pile, and the pile response is analyzed using traditional p-y curves and a beam on elastic foundation formulation. This procedure shows good agreement with the numerical model results for a range of conditions. To demonstrate the application of the procedure, the same example problem that is analyzed numerically is reanalyzed using the simplified analysis procedure. Due to the complexity of the problem, it was not possible to modify this procedure or develop a similar procedure for T-walls installed on top of new or existing levees. Overall, this research demonstrates that numerical models can be used to calculate the bending moments that can develop in pile-supported T-walls due to settlements and flood loading, provides valuable insights into the behavior of T-walls and the influence of various parameters on T-wall response, presents a large database of T-wall analysis results, and recommends a simplified analysis procedure that can be used in some cases to calculate pile bending moments due to settlements. / Ph. D.

The use of inclined piles is an efficient way to handle horizontal forces in constructions. However, if the soil settles the structural bearing capacity of each pile is reduced because of induced bending moments in the pile. There are several reasons for a soil to settle, e.g. if an embankment is built on top of a clay settlements will occur. There is currently no validated method in Sweden to analyse horizontal loading from a settling soil. In the current report a non-linear 3D finite element model is validated by a previously conducted field test and the results are compared to three different beam-spring foundations. These consist of a standard model where a subsoil reaction formulation is used, a model where the soil is considered as a distributed load, and a model with a wedge type of failure. Furthermore, a parametric study is conducted for a cohesionless material where the weight and friction angle of the soil material is varied. The standard soil reaction model yields an induced bending moment almost three times larger than the one obtained from the field test and the two other calculation methods. The latter beam-spring models should therefore be considered in practical design. These findings imply that inclined piles can be used in a far greater extent than previously expected, hence decreasing the cost for the project. / Användning av lutande pålar är ett väldigt effektivt sätt att ta hand om horisontalkrafter i konstruktioner. Om marken omkring pålen sätter sig orsakas ett böjmoment i pålen som sänker den strukturella bärförmågan av pålen. För närvarande finns ingen validerad metod i Sverige för att beräkna storleken av den horisontella kraften som orsakas av sättningarna. I den här studien har en ickelinjär 3D-FEM modell validerats mot ett tidigare utfört fullskaleförsök, dessa resultat har därefter jämförts mot tre olika 2D-diskretiseringar. Den första modellen som beskrivs är den som idag används vid påldimensioneringar. De två andra modellerna är baserade på en annan brottmekanism i påltoppen där jorden istället för en fjädermodell utgörs av en utbredd last med två olika formuleringar. Vidare har en parametrisk studie utförts med en friktionsjord där vikten och friktionsvinkeln på jordmaterial varierats. Den nuvarande 2D-diskretiseringen ger ett böjmoment i pålen som är närmare tre gånger större än det i fältförsöket uppmätta och de två föreslagna beräkningsmodellerna. Ett böjmoment så stort att pålens kapacitet teoretiskt blir obefintlig enligt nuvarande beräkningsmodell.

[pt] A constante expansão ocupacional de terrenos resulta na eventual construção sobre camadas de argila mole, o que requer a utilização de fundações em estacas e, com isso, maior conhecimento sobre o material do subsolo e a interação entre as estruturas. Em um projeto de fundações, a consideração das cargas transversais atuantes na superfície nem sempre é suficiente, é necessário adicionar as solicitações também impostas ao longo do seu comprimento. Este trabalho relata o caso de um edifício em Ubatuba/SP, que entrou em colapso devido a solicitações laterais no fuste das estacas próximas ao fundo do terreno, local com maior espessura de argila mole. Este movimento foi analisado por meio de quatro métodos convencionais (Tschebotarioff, De Beer e Wallays, Stewart e Goh), além do método numérico utilizando o software Plaxis em modelagens 2D e 3D. Os métodos convencionais apresentaram momentos fletores bastante divergentes entre si, porém todos apresentaram resultados cuja ordem de grandeza foi muito maior que os obtidos por meio da análise numérica. A modelagem bidimensional mostrou que o espaçamento entre estacas no eixo fora do plano é um fator com bastante influência e interfere nos valores resultantes do modelo 2D, outra constatação foi a redução de até 50 por cento dos momentos fletores atuantes quando considerado o efeito de grupo. Os resultados da modelagem 3D mostraram-se concordantes com os da modelagem 2D, chegando a apresentar uma divergência de 2 por cento entre os resultados. Em termos gerais, foi confirmada a maior solicitação nas estacas mais próximas ao limite posterior do terreno, onde se encontra a camada mais espessa de argila, o que gerou momentos maiores do que aqueles gerados pela carga transversal da superestrutura. / [en] The constant expansion of land occupation leads to the eventual construction over soft clay layers, requiring the use of foundation piles and thus, greater understanding of the subsurface material and the interaction between the structures, especially in regards to the induced loads and displacements. Naturally, the loads from the overhead structure are transmitted to the foundation, causing it to suffer from the action of axial and transverse loads. In a foundation design, the consideration of transverse loads acting on the surface is not always sufficient, making it necessary to include the loads imposed along its length as well. This study depicts the case of a building in Ubatuba/SP that collapsed due to lateral stresses along the middle section of the piles, located close to the farthest site boundary where a thicker layer of soft clay can be found. This movement was analysed using four conventional methods (Tschebotarioff, De Beer and Wallays, Stewart and Goh), as well as a numerical method for 2D and 3D modelling on the Plaxis software. The conventional methods presented diverging results relative to each other, of which. However, all four methods produced results with orders of magnitude much greater than those obtained through numerical analysis. The bidimensional model showed that the spacing between piles in the out-of-plane axis is a factor of great influence and interferes in the simplifications of the 2D model. Another finding was a reduction of up to 50 percent of the acting bending moments when considering the group effect. The results from the 3D model were in agreement with those from the 2D model, exhibiting only a 2 percent difference. In general, a greater load on the piles closest to the farthest limit of the site was confirmed, located on the thickest clay layer that generated bending moments greater than those generated from the transverse load of the structure.

<div>Underground structures must be able to support static overburden loads, as well as to accommodate additional deformations imposed by seismic motions. Progress has been made in the last few years in understanding the soil-structure interaction mechanisms and the stress and displacement transfer from the ground to the structure during a seismic event. It seems well established that, for most tunnels, the most critical demand to the structure is caused by shear waves traveling perpendicular to the tunnel axis. Those waves cause distortions of the cross section (ovaling for a circular tunnel, and racking for a rectangular tunnel) that result in axial forces (thrusts) and bending moments. While all this has been well-studied for structures placed in linear-elastic ground, there is little information regarding the behavior of buried structures placed in nonlinear ground, especially under undrained conditions, i.e., when excess pore pressures generate and accumulate during the earthquake.</div><div><br></div><div><div>Two-dimensional dynamic numerical analyses are conducted to assess the seismic response of deep circular tunnels located far from the seismic source, under drained or undrained loading conditions. It is assumed that the liner remains elastic and that plane strain conditions apply. </div><div> A new cyclic nonlinear elastoplastic constitutive model is developed and verified, to simulate the nonlinear behavior and excess pore pressures accumulation with cycles of loading in the ground. The results of the numerical analyses show negligible effect of input frequencies on the normalized distortions of a tunnel for input frequencies smaller than 5 Hz (the distortions of the tunnel are normalized with respect to those of the free field); that is, for ratios between the wavelength of the seismic input and the tunnel opening larger than about eight to ten. The results also show that undrained conditions, compared with drained conditions, tend to reduce deformations for flexible liners and increase them for stiffer tunnels, when no accumulation of pore pressures with cycles of loading is assumed. However, when pore pressures increase with the number of cycles, the differences in distortions between drained and undrained loading are reduced, i.e., the normalized distortions increase for flexible and decrease for stiff tunnels, compared to those with drained conditions. </div></div><div><br></div><div><div>Undrained loading produces larger thrust in the liner than drained loading for stiff tunnels with flexibility ratio F ≤ 2.0.</div><div>For more flexible tunnels with F > 2.0, the behavior is the opposite, i.e., smaller axial forces are obtained for undrained loading than for drained loading. Including excess pore pressure accumulation does not introduce significant changes in the axial forces of the liner, irrespective of the flexibility of the tunnel, compared to those obtained from undrained loading without pore pressure accumulation.</div><div>The drainage loading condition (drained or undrained) or the magnitude of the free-field excess pore pressures during undrained loading do not affect the normalized bending moments for flexible tunnels, with F ≥ 2. For stiffer tunnels, with F < 2, the normalized bending moments increase from drained to undrained loading, and with the free field excess pore pressures.</div></div><div><br></div><div><div>It is found that the tunnel’s response is determined by the load on the liner, or by the distortions of the cross section, depending on the flexibility ratio. For stiff structures, with F ≤ 2.0, important axial forces and bending moments are produced in the structure, with larger magnitudes for the undrained case; while the distortions of the cross section are very small. When the tunnel becomes more flexible, the loading on the liner decreases, but the distortions of the cross section start to be important. For flexible structures with initial F ≥ 10 (for the cases investigated), the performance is largely determined by the distortions of the cross section, while the axial forces and bending moments are almost negligible. Such distortions are drastically affected by the drainage loading condition and by the magnitude of pore pressures in the free field. </div></div><div><br></div>

Optimizing the operation and maintenance of wind turbines is crucial as the wind energy sector continues to expand. Predicting the mass imbalance of wind turbines, which can seriously damage the rotor blades, gearbox, and other components, is one of the key issues in this field. In this work, we propose a machine learning-based method for predicting the mass imbalance of wind turbines utilizing information from multiple sensors and monitoring systems. We collected data and trained the model from Adwen AD8 wind turbine model and evaluated on the real wind turbine SCADA data which is located at Fraunhofer IWES, Bremerhaven. The data included various parameters such as wind speed, blade root bending moments and rotor speed. We used this data to train and test machine learning classification models based on different algorithms, including extra-tree classifiers, support vector machines, and random forest. Our results showed that the machine learning models were able to predict the mass imbalance percentage of wind turbines with high accuracy. Particularly, the extra tree classifiers with blade root bending moments outperformed other research for multiclassification problem with an F1 score of 0.91 and an accuracy of 90%. Additionally, we examined the significance of various features in predicting the mass imbalance and observed that the rotor speed and blade root bending moments were the most crucial variables. Our research has significant effects for the wind energy sector since it offers a reliable and efficient way for predicting wind turbine mass imbalance. Wind farm operators can save maintenance costs, minimize downtime of wind turbines, and increase the lifespan of turbine components by identifying and eliminating mass imbalances. Also, further investigation will allow us to apply our method to different kinds of wind turbines, and it is simple to incorporate into current monitoring systems as it supports prediction without installing additional sensors. In conclusion, our study demonstrates the potential of machine learning for predicting the percentage of mass imbalance of wind turbines. We believe that our approach can significantly benefit the wind energy industry and contribute to the development of sustainable energy sources.

Master´s thesis is divided into two parts. In first part is author focusing on designing load-bearing structures that are made of reinforced concrete (floor slab, external wall, stairway). The assessments of those structures were made according to valid standard of ČSN EN 1992-1-1 and structural part of design documentation to those constructions were processed. In second, theoretical, part are different models of reinforced concrete slab in 3D (as part of whole construction) and in 2D created. The main task was to compare influence of different support´s stiffness in models on internal forces (bending moments) and on deflection of slab.

In this master’s thesis I study statical solution of new office building. The load – bearing elements are appraised according to ultimate limit state. Structural analysis contains of dimensioning ceiling plate with ribs, the most stressed support column and footing. There will be applied computer simulation to finding out values of internal forces. The solution is checked by simple method of replacement frames. The main purpose of this thesis consists of elaboration structural analysis, drawing up the technical report and creation design documents of load – bearing elements.

The final thesis is focused on the design of monolithic reinforced concrete ceiling slab and supporting vertical structures of typical floor of an administrative building. Calculation of internal forces is carried out in a computer software SCIA Engineer. Assessment is done according to Eurocode 2 (ČSN EN 1992-1-1).

In this diploma thesis „Static solution of hospital completion in Pisek“ I study statical solution of one new building of hospital. Statical solution includes the design and dimensioning of reinforced concrete floor structures and peripheral beams. The floor structure consists of point supported reinforced concrete slab. The floor slab is supported by columns and walls. The aim of the project is to desing and evaluate the ultimate limit state of reinforced concrete slab and beams. Also was created 3D computational model to analysis the construction, model was created in software Scia Engineer. To verify the resulting values of internal forces was used to the method of replacement frames. The thesis includes an analysis of internal forces in the structure, while based on different types of soil. Individual values are compared. Finally was made drawings of solved part of the building.

Diploma thesis is focused on the description of the parameters of nonlinear material models of concrete, which are implemented in a computational system LS-DYNA, interacting with performance of nonlinear test calculations in system LS-DYNA on selected problems, which are formed mainly by simulations of tests of mechanical and physical properties of concrete in uniaxial compressive and tensile on cylinders with applying different boundary conditions and by simulation of bending slab, with subsequent comparison of some results of test calculations with results of the experiment. The thesis includes creation of appropriate geometric models of selected problems, meshing of these geometric models, description of parameters and application of nonlinear material models of concrete on selected problems, application of loads and boundary conditions on selected problems and performance of nonlinear calculations in a computational system LS-DYNA. Evaluation of results is made on the basis of stress-strain diagrams and load-displacement diagrams based on nonlinear calculations taking into account strain rate effects and on the basis of hysteresis curves based on nonlinear calculations in case of application of cyclic loading on selected problems. Verification of nonlinear material models of concrete is made on the basis of comparison of some results of test calculations with results obtained from the experiment.