Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Numerical Modelling of Failure in 3d Quasi-Brittle Unreinforced Structural Components(Izmir Institute of Technology, 2022) Kaçmaz, Bekir; Özdemir, İzzetConcrete has been one of the most commonly used modern structural material with quasi-brittle response. Because of its wide usage, numerical prediction of crack path and failure of structural components made of concrete and reinforced concrete has a great importance. To achieve this goal, a wide range of techniques have been introduced by treating fracture differently. In addition, the development of successful element formulations in analysis of 3D structural components has also been an active research topic. Several formulations have been proposed as an alternative to the conventional Lagrangian elements in recent years. In this thesis, localizing implicit gradient damage model and an isogemetric tetrahedral element are combined to investigate failure of 3D quasi-brittle unreinforced structural components. 10 noded B´ezier tetrahedral element is implemented to commercial finite element software Abaqus through user defined element subroutine, UEL. The implementation is validated by using two benchmark problems with nearly incompressible linear elastic and elasto-plastic material behaviors. After validating the implemented element, the formulation is extended such that localizing implicit gradient damage model is embedded within the isogeometric element formulation. Resulting two field formulation is tested on 3D experimental studies that exhibit complex fracture propagation due to combined torsional and bending moments. The sufficiency of the implemented two field formulation is verified by comparing obtained results with the experimental ones in terms of both force versus displacement responses and resulting crack paths.Master Thesis Investigation of the Effect of Structural Grid Discontinuity on the Earthquake Behavior of Midrise Rc Moment Frames(Izmir Institute of Technology, 2019) Gemici Yormaz, Mefküre Banu; Dönmez, CemallettinReinforced concrete (RC) moment frames are the most common form among the building type structures in Turkey. The contemporary seismic design of building type structures evolves around the definition of deviations from an ideal structure that has a square-like floor plan, symmetric and uniform framing and mass distribution. These deviations are called the irregularities which are grouped in two as horizontal and vertical irregularities. There exists a horizontal irregularity that is not addressed in the current approach but it is needed to be investigated due to its possible impact on the lateral stiffness of the structure. It is the discontinuity of the horizontal grid in the structural frame. The purpose of this study is to investigate the earthquake response of the RC buildings that have horizontal grid discontinuities. It is intended to observe the level of additional vulnerability on the seismic response of RC moment frames due to this irregularity. Two 5-story reinforced concrete buildings are modeled in order to investigate the effects of the grid discontinuity phenomenon using nonlinear time-history analysis. The first building has discontinuous beams and framing that demonstrates the irregularity in the plan while the second one is the control case with uniform structural framing. The results are evaluated based on the member damage level. It is observed that the buildings with grid discontinuities are more vulnerable than those without irregularities to seismic excitation. Further study is needed to define a procedure to mitigate the vulnerability created by the horizontal grid discontinuity.