Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.İşbuğa, Volkan

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Now showing 1 - 4 of 4
  • Master Thesis
    Response of Vertically Loaded Energy Piles Under Earthquake Excitation
    (2023) İşbuğa, Volkan; İşbuğa, Volkan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Pile foundations are deep foundation systems that are used to transfer loads from superstructure to soil by either resisting surface friction or reaching a deeper and stiffer soil layer when geotechnical properties of the soil site are not sufficient to carry the loads transferred from superstructure. Energy piles fulfill the same function along with the ground heat exchanging via heat pump systems, thus satisfying the energy demand of a building for heating-cooling operations. This feature of energy piles draws attention as an innovative system supplying a renewable energy resource. However, heat exchanging operations of energy piles cause temperature variations on pile and the surrounding soil which may cause additional load and deformations. Moreover, temperature variations may affect the elasticity modulus of soils and shear strength of cohesive soils. In this study, earthquake response of an axially energy loaded pile was investigated considering the heating effect under 2020 Izmir earthquake motion using finite element method and compared to the those of identical regular piles. We performed analyses with different soil types, geometric properties, and temperature magnitudes under steady-state heating. Based on the analysis results, heating effect on pile head stiffness with respect to geometric properties were obtained. Two important conclusions have been made; (i) the most critical effect on heating depends on mechanical loading condition of pile and thermal expansion coefficient of soil, (ii) geometric properties may affect the temperature distribution resulting in an unforeseen change in pile head stiffness.
  • Master Thesis
    Modelling Vertically Loaded Pile Groups by Considering Pile-Soil Interactions
    (2023) İşbuğa, Volkan; İşbuğa, Volkan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The aim of the study presented in this thesis is to create a model that takes into account the interaction between piles for the analysis of pile groups embedded in a linear elastic medium. This research builds upon prior work by Vallabhan and Mustafa (1996) introduced a single pile model and the pile-soil-pile interaction model proposed by İşbuğa (2023). The model has undergone further development to encompass the entire spectrum of pile groups regardless of how many piles it has and what kind of layout it has. This comprehensive model addresses two distinct scenarios: one involving a free-head pile group and another featuring a pile group that has a rigid pile cap. In the context of a free-head pile group, single piles within the group show different displacements due to load and interactions. On the other hand, in the case of a rigid pile cap, the piles must have equal displacements because of the rigid nature of the pile cap. Two different algorithms have been developed for both of these scenarios, and these algorithms have been implemented using the Python programming language. The model has been used to analyze various pile groups, and the analysis results were compared with previous studies and finite element method solutions. In addition to comparing the results, the computation times of the models proposed by this study and those of the finite element method were also compared.
  • Master Thesis
    The Modified Vlasov Foundation on Nonlinear Soil Layers
    (01. Izmir Institute of Technology, 2021) Çerezci, Mehmet; İşbuğa, Volkan; İşbuğa, Volkan; İşbuğa, Volkan; 03.03. Department of Civil Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    In this thesis, a novel approach to account for the soil nonlinearity of nonhomogeneous soil deposits by employing the modified Vlasov foundation model is developed. A new algorithm that takes the modulus degradation curves at varying strain levels into account in an iterative manner is obtained by modifying the previously developed formulation. The presented model will provide researchers with the opportunity to employ the experimental test data directly for an operational strain level that may occur in many foundation engineering designs. This new model which takes the nonlinear soil behavior into account is first verified against the linear model given in the literature to ensure that the new model algorithm can capture the linear solution when the soil behavior is assumed to be linear. Later, the experimental data of modulus reduction curves reported in the literature for a specific type of dense and loose sands are used in multiple foundation deflection analyses. Example problems are considered for different cases which presented: (i) how the model captures nonlinear behavior and (ii) the significant effect of the nonlinear soil behavior on deflection, moment, and shear force. The model results are also compared with the finite element model result, assuming a bilinear stress-strain soil model. The results obtained from both models matched well, especially for the maximum deflection values that occurred in the example problems.
  • Master Thesis
    Impact of Urbanization on Hydrogeodynamic Systems: a Case Study: Bornova Region (i̇zmir, Turkey)
    (01. Izmir Institute of Technology, 2021) İşbuğa, Volkan; Öztürk, Bahadır; Baba, Alper; Baba, Alper; İşbuğa, Volkan; 03.03. Department of Civil Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    Urbanization is one of the most critical processes affecting land and water use. Understanding urbanization and its impact on ground systems gained prominence with global climate change and population increase. This study focuses on the new city center Bornova Plain, İzmir; Turkey, used as agricultural land until the 1950s. Later, the region was opened for settlement, and excessive urbanization decreased the hydraulic conductivity of the surface area of the plain with the constructed buildings, road pavements, and other surface coverings. Effects of the land use- land cover changes on the hydrodynamic system of Bornova Plain's aquifers were investigated in three parts. Firstly, GIS-based hydrological models with two different periods (2004 and 2020) scenarios were developed with ArcSWAT for this thesis. Using SWAT models, elements of the water budget equation were determined. With SWAT Models, Recharge/Precipitation, Streamflow/Precipitation, and Baseflow/Total flow ratios were found to decrease 52%, 26.09%, and 11.86%, respectively, and Surface Runoff/Total Flow, and ET/Precipitation ratios were found to increase 20.59%, and 15.09% with urbanization increment comparing 2004 and 2020. Secondly, soil's bearing capacity changes with groundwater level changes within a year were investigated using five observation wells. Conceptual models were created for each well. Maximum of 14.82% of bearing capacity change was observed in the wells. Thirdly, PLAXIS 3D models were created to understand the effect of the groundwater level changes on pile settlements for sandy and clayey soils in the region. Conceptual models created and maximum of 12.74% settlement difference was observed for different groundwater levels.