L’ambition de ce travail est la prédiction du champ d’onde incident réalistique, induit par des mouvement forts de sol, aux sites d’importance stratégique, comme des centrales nucléaires. À cette fin, un plateforme multi-outil est développé et exploité pour simuler les aspects différents d’un phénomène complexe et multi-échelle comme un tremblement de terre. Ce cadre computationnel fait face à la nature diversifiée d’un tremblement de terre par approche holistique local-régionale.Un cas d’étude complexe est choisie: le tremblement de terre MW6.6 Niigata-Ken Ch¯uetsu-Oki, qui a endommagé la centrale nucléaire de Kashiwazaki-Kariwa. Les effets de site non-linéaires observés sont à premier examinés et caractérisés. Dans la suite, le modèle 3D «de la faille au site» est construit et employé pour prédire le mouvement sismique dans une bande de fréquence de 0-7 Hz. L’effet de la structure géologique pliée au-dessous du site est quantifié en simulant deux chocs d’intensité modérée et en évaluant la variabilité spatiale des spectres de réponse aux différents endroits dans le site nucléaire. Le résultat numérique souligne le besoin d’une description plus détaillée du champ d’onde incident utilisé comme paramètre d’entrée dans la conception structurel antisismique de réacteurs nucléaires et des installations. Finalement, la bande de fréquences des signaux synthétiques obtenues comme résultat des simulations numériques est agrandie en exploitant la prédiction stochastique des ordonnées spectrales à courte période fournies par des Réseaux Artificiels de Neurones. / The ambition of this work is the prediction of a synthetic yet realistic broad-band incident wave-field, induced by strong ground motion earthquakes at sites of strategic importance, such as nuclear power plants. To this end, an multi-tool platform is developed and exploited to simulate the different aspects of the complex and multi-scale phenomenon an earthquake embodies. This multi-scale computational framework copes with the manifold nature of an earthquake by a holistic local-to-regional approach. A complex case study is chosen to this end: is the MW6.6 Niigata-Ken Ch¯uetsu-Oki earthquake, which damaged the Kashiwazaki-Kariwa nuclear power plant. The observed non-linear site-effects are at first investigated and characterized. In the following, the 3D source-to-site model is constructed and employed to provide reliable input ground motion, for a frequency band of 0-7 Hz. The effect of the folded geological structure underneath the site is quantified by simulating two aftershocks of moderate intensity and by estimating the spatial variability of the response spectra at different locations within the nuclear site. The numerical outcome stresses the need for a more detailed description of the incident wave-field used as input parameter in the antiseismic structural design of nuclear reactors and facilities. Finally, the frequency band of the time-histories obtained as outcome of the numerical simulations is enlarged by exploiting the stochastic prediction of short-period response ordinates provided by Artificial Neural Networks.

This study presents a ground-motion selection and scaling procedure that preserves the inherent uncertainty in the modified recordings. The proposed procedure provides a set of scaled ground-motion records to be used in the response estimation of structural systems for a pre-defined earthquake hazard level. Given a relatively larger ground-motion dataset, the methodology constrains the selection and scaling of the accelerograms to the differences between individual records and corresponding estimations from a representative ground-motion predictive model. The procedure precisely calculates the distribution parameters of linear structural systems whereas it provides estimations of these parameters for nonlinear structural response. Thus this method is not only useful for ground-motion selection and scaling but also for probability based performance assessment studies. The proposed procedure is also capable of matching with a pre-defined target elastic response spectrum and corresponding variance over a period range. Case studies that compare the performance of the proposed procedure with some other record selection and scaling methods suggest its usefulness for the accurate verification of structural systems and rapid loss estimation studies.

Bolu-Ilgaz region was damaged by several large earthquakes in the last century and the structural damage was substantial especially after the 1944 and 1999 earthquakes. The objective of this study is to build the seismic source characterization model for the rupture zone of 1944 Bolu-Gerede earthquake and perform probabilistic seismic hazard assessment (PSHA) in the region. One of the major improvements over the previous PSHA practices accomplished in this study is the development of advanced seismic source models in terms of source geometry and reoccurrence relations. Geometry of the linear fault segments are determined and incorporated with the help of available fault maps. Composite magnitude distribution model is used to properly represent the characteristic behavior of NAF without an additional background zone. Fault segments, rupture sources, rupture scenarios and fault rupture models are determined using the WG-2003 terminology. The Turkey-Adjusted NGAW1 (G&uuml / lerce et al., 2013) prediction models are employed for the first time on NAF system. The results of the study is presented in terms of hazard curves, deaggregation of the hazard and uniform hazard spectrum for four main locations in the region to provide basis for evaluation of the seismic design of special structures in the area. Hazard maps of the region for rock site conditions and for the proposed site characterization model are provided to allow the user perform site-specific hazard assessment for local site conditions and develop site-specific design spectrum. The results of the study will be useful to manage the future seismic hazard in the region.

Earthquake-induced slope instability is one of the major sources of earthquake hazards in near fault regions. Simplified tools, such as Newmark&rsquo / s Sliding Block (NSB) Analysis are widely used to represent the stability of a slope under earthquake shaking. The outcome of this analogy is the slope displacement where larger displacement values indicate higher seismic slope instability risk. Recent studies in the literature propose empirical models between the slope displacement and single or multiple ground motion intensity measures such as peak ground acceleration or Arias intensity. These correlations are based on the analysis of large datasets from global ground motion recording database (PEER NGA-W1 Database). Ground motions from earthquakes occurred in Turkey are poorly represented in NGA-W1 database since corrected and processed data from Turkey was not available until recently. The objective of this study is to evaluate the compatibility of available NSB displacement prediction models for the Probabilistic Seismic Hazard Assessment (PSHA) applications in Turkey using a comprehensive dataset of ground motions recorded during earthquakes occurred in Turkey. Then the application of selected NSB displacement prediction model in a vector-valued PSHA framework is demonstrated with the explanations of seismic source characterization, ground motion prediction models and ground motion intensity measure correlation coefficients. The results of the study is presented in terms of hazard curves and a comparison is made with a case history in Asarsuyu Region where seismically induced landslides (Bakacak Landslides) had taken place during 1999 D&uuml / zce Earthquake.

Ground-motion data processing is a necessity for most earthquake engineering related studies. Important engineering parameters such as the peak values of ground motion and the ordinates of the response spectra are determined from the strong ground-motion data recorded by accelerometers. However, the raw data needs to be processed since the recorded data always contains high- and low-frequency noise from different sources. Low-cut filters are the most popular ground-motion data processing scheme for removing long-period noise. Removing long-period noise from the raw accelogram is important since the displacement spectrum that provides primary information about deformation demands on structural systems is highly sensitive to the long-period noise. The objective of this study is to investigate the effect of low-cut filtering period on linear and nonlinear deformation demands. A large number of strong ground motions from Europe and the Middle East representing different site classes as well as different magnitude and distance ranges are used to conduct statistical analysis. The statistical results are used to investigate the influence of low-cut filter period on spectral displacements. The results of the study are believed to be useful for future generation ground-motion prediction equations on deformation demands that are of great importance in performance-based earthquake engineering.

In this study, the seismic fragility assessment of low-rise and mid-rise reinforced concrete frame buildings which constitute approximately 75 % of the total building stock in Turkey is investigated to quantify the earthquake risk. The inventory used in this study is selected from D&uuml / zce damage database which was compiled after the devastating 1999 earthquakes in the Marmara region. These buildings are not designed according to the current code regulations and the supervision in the construction phase is not adequate. The building database is divided into sub-classes according to the height and absence of infilled walls. Each building in the database is represented by an equivalent single degree of freedom system with three structural parameters: period, strength, and post-elastic stiffness ratio. The ground motion records are selected from different parts of the world covering a wide range of characteristics. The capacity of the structure is represented for each sub-class by the limit states. Hence, a set of fragility curves for low- and mid-rise reinforced concrete structures are developed by making use of the building characteristics in the database. The generated fragility curve set is referred as &ldquo / reference&rdquo / since it forms the basis of a parametric study. A parametric study is conducted to examine the influence of post-elastic stiffness ratio, simulation and sampling techniques, sample size, limit state definition and degrading behavior on the final fragility curves. Estimated damage distribution after two consecutive major earthquakes is compared with the actual field data in order to investigate the validity of the generated fragility curves.

In this study, the limitations of point-source stochastic simulations are investigated in terms of fundamental geophysical parameters. Within this context, a total of 6000 synthetic ground motions are generated for various magnitude (5.0 &amp / #8804 / Mw &amp / #8804 / 7.5), source-to-site distance (less than 100 km), faulting style (shallow dipping and strike-slip) and site class (soft, stiff and rock) bins. The simulations are performed in two main stages: (1) the acceleration time series at outcropping very hard rock sites are simulated based on the stochastic method proposed by Boore (1983, 2003) and (2) they are modified through 1-D equivalent linear site response analysis to generate the free-field motions at soft, stiff and rock sites. Thus, as a part of this study, a probability-based soil profile model that considers the random variation of S-wave slowness as a function of depth is derived. The synthetic ground motions are assessed with several recent empirical ground-motion models to constitute the limitations of the simulation procedure. It is believed that the outcomes of this study will realistically describe the limitations of stochastic point-source simulation approach that can be employed further for the studies on improvements of this simulation technique.

Prior to this study, to our best knowledge, no cast-in-place, older-type RC building has ever been subjected to near-field strong ground motions from three major earthquakes. This happened in an indirect way in Turkey over a time span of eleven years. Three identical buildings belonging to Ministry of Public Works and Resettlement (MPWR) that had been built to the same design templates, experienced March 13th 1992 Erzincan earthquake in Erzincan, November 12th 1999 D&uuml / zce earthquake in Bolu and May 1st 2003 Bing&ouml / l earthquake in Bing&ouml / l, respectively. The ground motion sensor stations were fortuitously nearby in an adjacent single-story building in Bolu and Bing&ouml / l. The station in Erzincan was in a single-story building about 2 km away from the case study building but we assume that the record applies to the building there. These three data represent characteristics of near-field ground motions and the distance of the sensor stations to the nearest fault trace was less than 10 km. The buildings sustained varying degrees of damage during the earthquakes and their damage survey was employed through site investigations. Given that the damage information, input motions, design drawings and material properties of the buildings are all known, this provided an opportunity to predict the structural damage to these buildings by proper modeling using the tools of current computational performance assessment procedures. In this circumstance, three dimensional (3D) analytical models of the MPWR buildings have been performed. Bi-directional excitations have been applied to the models by nonlinear time history analyses (NTHA). The results illustrate that NTHA are capable of indicating the occurrence of shear failure in captive columns / however, they overestimate the global damage level for all buildings. The overestimation is more significant in Erzincan case where the building sustained a pulse-type motion without significant distress.

The primary objective of this study is to evaluate the seismic hazard in the Eastern Marmara Region using improved seismic source models and enhanced ground motion prediction models by probabilistic approach. Geometry of the fault zones (length, width, dip angle, segmentation points etc.) is determined by the help of available fault maps and traced source lines on the satellite images. State of the art rupture model proposed by USGS Working Group in 2002 is applied to the source system. Composite reoccurrence model is used for all seismic sources in the region to represent the characteristic behavior of North Anatolian Fault. New and improved global ground motion models (NGA models) are used to model the ground motion variability for this study. Previous studies, in general, used regional models or older ground motion prediction models which were updated by their developers during the NGA project. New NGA models were improved in terms of additional prediction parameters (such as depth of the source, basin effects, site dependent standard deviations, etc.), statistical approach, and very well constrained global database. The use of NGA models reduced the epistemic uncertainty in the total hazard incorporated by regional or older models using smaller datasets. The results of the study is presented in terms of hazard curves, deaggregation of the hazard and uniform hazard spectrum for six main locations in the region (Adapazari, Duzce, Golcuk, Izmit, Iznik, and Sapanca City Centers) to provide basis for seismic design of special structures in the area. Hazard maps of the region for rock site conditions at the accepted levels of risk by Turkish Earthquake Code (TEC-2007) are provided to allow the user perform site-specific hazard assessment for local site conditions and develop site-specific design spectrum. Comparison of TEC-2007 design spectrum with the uniform hazard spectrum developed for selected locations is also presented for future reference.

Isolator displacements, floor accelerations, roof displacements, base shear and torsional moments are basic parameters that are considered in the design of seismically isolated structures. The aim of this study is to evaluate the effects of bidirectional earthquake excitations of near fault records on the response of base isolated structures in terms of basic parameters mentioned above. These parameters computed from nonlinear response history analysis (RHA) and they are compared with the parameters computed from equivalent lateral force procedure (ELF). Effect of asymmetry in superstructure is also examined considering mass eccentricity at each floor level. Torsional amplifications in isolator displacements, floor accelerations, roof displacements and base shear are compared for different level of eccentricities. Two buildings with different story heights are used in the analyses.The building systems are modeled in structural analysis program SAP2000. The scaling of ground motion data are taken from the study of &ldquo / Response of Isolated Structures Under Bi-directional Excitations of Near-fault ground Motions&rdquo / (Ozdemir, 2010). Each ground motion set (fault normal and fault parallel) are applied simultaneously for different range of effective damping of lead rubber bearing (LRB) and for different isolation periods.