Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Seismic Analysis of an Ancient Lighthouse by Meso-Scale Modeling Technique(01. Izmir Institute of Technology, 2020) Gözün, Safiyullah Üveys; Özdemir, İzzet; Dönmez, CemalettinModeling masonry structures has always been a difficult subject due to the lack of information about the behavior, the heterogeneity of the masonry materials and complex geometries of masonry structures. In terms of the computational costs and complexity, several methods are proposed in the literature. In this thesis, the capabilities of the meso-scale modeling technique are investigated by means of two experiments selected from the literature and the seismic response of an ancient lighthouse. Brick and mortar type structure is idealized as expanded units surrounded by zero thickness cohesive interfaces representing the mortar behavior. This means that the failure of mortar layers is considered explicitly by means of cohesive surfaces whereas the mechanical response of expanded units is described by Drucker-Prager/Cap model. This approach is used to simulate the in-plane and the outof-plane behavior of masonry walls reported in the literature. After validating the models with the experimental results, implicit-dynamic time history analyses of an ancient lighthouse are conducted by using 2 different earthquake records. The influence of mortar properties on the energy dissipation mechanisms and collapse pattern of the structure are investigated by means of a parametric study. As an attempt to identify the critical earthquake level corresponding to the initiation of sliding within the lighthouse, a set of additional analyses are conducted with scaled earthquake records.Master Thesis Effect of Infill Wall Stiffness Variations on the Behavior of Reinforced Concrete Frames Under Earthquake Demands(Izmir Institute of Technology, 2013) Sönmez, Egemen; Dönmez, CemalettinReinforced concrete (RC) structures with infill walls are the most common building types in earthquake-prone regions of Turkey. Due to the complications in modeling the infill wall - frame interaction, they are generally neglected in structural design. However, presence of the infill walls has been proved to affect stiffness, strength and behavior of the structures significantly. Effects of infill walls may be either beneficial or detrimental under seismic demands. Infill walls typically increase the stiffness and strength of the structures. This situation may be advantageous for nonductile buildings up to a certain limit. However, brittle nature and variety of failure modes of infill walls may cause unforeseen and irreversible damages. Particularly, softstory mechanisms may occur due to drift concentrations at lower stories. An organized stiffness distribution along the height of the structure may help mitigating these negative effects. The main purpose of the study is to investigate the effects of stiffness variations in infill walls to the behavior of the frames. In order to achieve the purpose, an analytical software that supports an infill model, was selected. The software is calibrated and verified by simulating a series of experiments. Afterwards, a planar, fivestory, five-bay reinforced concrete frame was designed with common deficiencies observed in residential buildings in Turkey. The performance of the bare frame (BF) was determined using pushover analysis. Then, two types of infilled frames were obtained by introducing infill walls into two bays. The infill walls of the first infilled frame (IF-1) had a uniform stiffness and strength distribution along the height of the frame. In the second infilled frame (IF-2), the stiffness and strength of the infill walls had a decreasing profile from the bottom to the top story. By this distribution, drift concentration at the lower stories was aimed to be mitigated. Nonlinear dynamic and pushover analyses were performed on the frames. The results indicated that the organized stiffness distribution of IF-2 mitigated the drift concentrations and improved he seismic performance of the frame.