Ph.D. Theses
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Browsing Ph.D. Theses by Subject "Earthquake hazard analysis."
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Item A seismic vulnerability analysis procedure for urban loss assessment(Thesis (Ph.D.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2008., 2008.) Tüzün, Cüneyt.; Aydinoğlu, M. Nuray.The assessment of seismic vulnerability of buildings in seismically active urban areas is of great importance in terms of engineering, economical and social aspects. In this study an analytical procedure has been developed in order to obtain the vulnerability functions of existing buildings. The building information included over all geometry of the structure, as-built dimensions and configuration of the structural members, complete with reinforcement details of beams and columns, which are extracted from the design dossiers available in the Bolu municipality archives. Totally 120 buildings, 20 from each class, are classified depending on their number of stories ranging from 2 to 7 story and nonlinear response history analysis has been performed in order to obtain damage distributions by using 20 spectrum compatible ground motions. In the first chapter a brief explanation of the role of loss estimation studies in urban planning, urban disaster management and mitigation has been given. In the second chapter, existing building vulnerability relationships have been evaluated and particular examples of studies that have made important contribution to the development are briefly cited. In the third chapter, basic steps of a standard derivation of analytical vulnerability functions are identified and the importance of each step in the process has been explained. In the fourth chapter, the procedure based on real building data has been explained in detail including the ground motion characterization, properties of building data, analytical methods used in the analysis, damage definition and quantification, statistical process and the determination of the vulnerability parameters. Results are presented in the form of lognormal vulnerability curves with respect to spectral acceleration or spectral displacement. In the fifth chapter, the conclusions are presented and the contribution of the study to the existing knowledge in the field has been evaluatedItem Characterization of response spectra for near field conditions by earthquake ground motion simulation(Thesis (Ph.D.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2007., 2007.) Şeşetyan, Karin.; Erdik, Mustafa.; Madariaga, Raul.Strong ground motion estimation tools such as empirical ground motion prediction equations rely mostly on recorded data. Good quality strong motion data became available mostly in recent years and are still sparse for near field conditions. Strong ground motion records on the other hand contain them several characteristics such as source, path and especially local site effects. These features can sometimes be hardly differentiated when one is willing to study only one of them. As such, realistic simulation of the 3D wavefield generated by a fault rupture in a heterogeneous medium becomes critical for the study of strong ground motion. Particularly features such as intra-event and inter-event spatial and temporal variability of ground motion can be studied in detail. With increasing computational power and newly emerged methods such simulations become increasingly feasible. In this study I use kinematic simulation with 3D Staggered Grid Finite Difference method to study the characteristics of near source effects of strong ground motion. I also aim to prove that kinematic simulation with 3D Staggered Grid Finite Difference method (3DFD) is a useful tool to analyze and estimate the characteristics of long period strong ground motion. For this purpose first a simulation model has been set for the 2004 Mw=6.0 Parkfield earthquake. Making use of the available 3D crustal velocity structure of the region and several slip models of the earthquake over 40 near source recordings produced by the event have been simulated. Encouraged by the very good agreement between observed and simulated waveforms, 3DFD has been used for the characterization of directivity effects in the near source region. Eleven earthquakes covering a magnitude range from 6.0 to 7.4 have been modeled using one or more slip models for each of them. Eight of these events had a strike-slip mechanism whereas the remaining ones were dip-slip events. Resulting spatial distributions of fault parallel, fault normal and average response spectral accelerations at longer periods have been analyzed to derive general formulations for the modification of the response spectral values found from earthquake hazard analysis to include near source directivity effects. With recently emerging structural design methods, engineering studies concentrate more and more on the long period characteristics of strong ground motion. The present study validates kinematic simulation tools, particularly the 3DFD method used herein as a useful method for the simulation of low frequency strong ground motion in realistic earth media for engineering purposes.