Master Degree / Yüksek Lisans Tezleri

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

Browse

Filters

2013 - 20205

Settings

Access Right: Open AccessSubject: search.filters.subject.Earthquake engineering

Search Results

Now showing 1 - 5 of 5
  • Master Thesis
    A Case Study: Site-Specific Seismic Response Analysis for Base-Isolated Building in Düzce
    (01. Izmir Institute of Technology, 2020) Eren, Volkan Gökçe; Ecemiş Zeren, Nurhan
    Under seismic loads, soil-structure interaction, and its effect on performance of pavements is more important today. Turkey is located in one of the most active seismic zones in the world. In the past, many destructive earthquakes happened in Turkey. The fact is that due to frequent earthquakes in the future, we may suffer a significant loss of life and property. Therefore, it has been necessary to minimize demolitions by conducting soil behavior analysis for each site. To design buildings, bridges, and other structures with base-isolators according to performance, it is necessary to carefully evaluate the long-term ground motions, especially in determining the earthquake ground motion. In these evaluations, empirical and theoretical methods to predict the response spectrum, considering and analyzing the effects of the near-fault, scaling the spectrum for different damping ratios, and simulation of long-term ground motions time-history constitute an essential place. It is necessary to determine the principles required for modifying the design spectrum in the long-period boundaries. The regulations are required to simulate long-period ground motions in the time-history and the necessary rules for selecting and scaling the earthquake ground motion records by considering the long-period effect. In this thesis, commonly used approaches in national and international regulations in defining the earthquake effect were evaluated, and the recommended earthquake levels for structures within the Düzce city in Turkey are explained. While evaluating the earthquake hazard in the study area, the general geology, tectonic features, ground conditions, and existing fault systems of the region were considered. For the study area, besides the classical hazard spectra, hazard curves for different spectral ordinates that allow the calculation of probabilistic seismic hazard maps and spectral coordinates for various periods are presented. Earthquake records were selected according to these spectra, and nonlinear analyses were made by simulating earthquake data for structural analysis. Turkey Earthquake Building Regulations (TBDY, 2018) to determine the seismic design spectrum is considered.
  • 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, Cemalettin
    Modeling 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
    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, Cemallettin
    Reinforced 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.
  • Master Thesis
    Effects of Consolidation Characteristics on Cpt Cone Resistance and Liquefaction Resistance in Silty Soils
    (Izmir Institute of Technology, 2013) Karaman, Mustafa; Ecemiş, Nurhan
    One of the most important reasons of the life and property losses caused by earthquakes is liquefaction during or after the earthquakes. Many researches focused on liquefaction after the earthquakes have revealed that liquefaction occurs mostly in silty soils. Empirical relationships between normalized cone penetration resistance (qc1N), cyclic resistance ratio (CRR), magnitude of earthquake (Mw), and silt content (FC), derived from field observations, are currently used for liquefaction potential assessment of loose saturated sands and silty sands. However, the effects of fine content on liquefaction resistance and penetration resistance are not defined clearly in these researches. For this reason, it is aimed to investigate the effects of fine content on consolidation characteristics and the effects of coefficient of consolidation on liquefaction resistance and cone penetration resistance. In this study, a number of field and laboratory studies were carried out to investigate the existing relationships. According to the results of experimental studies, first, the effects of the fines content on coefficient of consolidation and drainage characteristics of soils for different soil density ranges are examined and it is established that, both the fines content and the relative density effect the coefficient of consolidation of the sands and silty sands. Second, the changes in cone penetration resistance are investigated for different range of fines content and the relative density which have significant influence on coefficient of consolidation. It has been realized that the coefficient of consolidation indicates a significant influence on the measured penetration resistance during penetration of the CPT cone to the soil having different relative density, and it is figured out that for stiff-dense to medium dense soil, the decrease of normalized cone resistance is observed due to the change in drainage characteristics of fines or coefficient of consolidation. On the other hand, for loose soils only the relative density indicates a significant influence on the measured CPT penetration resistance around the probe. Finally, the contribution of the relative density on the liquefaction resistance of soils is observed at different fines content and compared with the available method in the literature.
  • 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, Cemalettin
    Reinforced 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.