Sentetik yer hareketleri ile sahaya özel sabit tehlike spektrumu çıkarılması ve bina kırılganlık eğrileri üzerindeki parametrik etkileri.

Estimation of seismic demands is essential for the purpose of structural seismic design and analyses. It is significant to obtain reliable ground motion amplitudes to estimate seismic damage on structures in a realistic manner. The ground motion simulation methodologies provide a physical approach to estimate seismic demands in the regions with sparse recording data and scarce networks. This dissertation consists of two main parts: In the first part, site-specific uniform hazard spectrum (UHS) of Erzincan region in Eastern Turkey is derived based on a stochastically-generated earthquake catalog and simulated ground motions. During the generation of the catalog, Monte Carlo simulation methodology is employed to determine spatial and temporal distribution of events. The magnitude of each event is obtained through Gutenberg-Richter recurrence relationship. Stochastic point-source and finite-fault simulation methodologies are used to calculate ground motion amplitudes. The effects of near-field forward directivity and alternative site amplification functions are studied on the proposed UHS. In the second part, the effect of proposed seismic hazard is studied on structural response and fragility. The selected ground motions from the first part are applied for nonlinear time history analyses of equivalent single degree freedom systems (ESDOF). ESDOF systems are developed such that they represent typical low-rise and mid-rise residential buildings in Erzincan. Fragility curves of building groups are then calculated based on demand predictive models. The effects of site conditions, near-field forward directivity, alternative site amplification functions and structural variability are studied on fragility functions. This study is an alternative approach to estimate seismic hazard for the regions with sparse data in which ground motion prediction equations (GMPE) may not be adequate. The proposed approach produces a regional UHS based on physical properties and complex seismicity parameters. The derived UHS mostly yield lower ground motion amplitudes than classical probabilistic seismic hazard analysis (PSHA) due to large aleatory variability inherent in PSHA. The effects of near-field forward directivity and detailed local site conditions are investigated on seismic hazard and building fragility in a practical manner. Additionally, this study provides a complete simulated ground motion database based on regional characteristics which are applied to perform sensitivity analyses of fragility functions to seismicity parameters.Ph.D. - Doctoral Progra

Using pad-stripped acausally filtered strong-motion data

Abstract Most strong-motion data processing involves acausal low-cut filtering, which requires the addition of sometimes lengthy zero pads to the data. These padded sections are commonly removed by organizations supplying data, but this can lead to incompatibilities in measures of ground motion derived in the usual way from the padded and the pad-stripped data. One way around this is to use the correct initial conditions in the pad-stripped time series when computing displacements, velocities, and linear oscillator response. Another way of ensuring compatibility is to use postprocessing of the pad-stripped acceleration time series. Using 4071 horizontal and vertical acceleration time series from the Turkish strong-motion database, we show that the procedures used by two organizations-ITACA (ITalian ACcelerometric Archive) and PEER NGA (Pacific Earthquake Engineering Research Center-Next Generation Attenuation)-lead to little bias and distortion of derived seismic-intensity measures

Site-specific uniform hazard spectrum in Eastern Turkey based on simulated ground motions including near-field directivity and detailed site effects

In this study, stochastic earthquake catalog of the Erzincan region in Turkey is generated based on synthetic ground motions. Monte Carlo simulation method is used to identify the spatial and temporal distribution of events. Ground motion time histories are generated using stochastic simulation methodology. Annual exceedance rate of each ground motion amplitude is calculated through statistical distribution of the complete set of ground motions. The results are compared with classical probabilistic seismic hazard analysis (PSHA). Classical PSHA generally produces larger spectral amplitudes than the proposed study due to wide range of aleatory variability. The effects of near-field forward directivity and detailed site response are also investigated on the results

The effect of structural variability and local site conditions on building fragility functions

In this study, the effect of local site conditions (site class and site amplifications) and structural variability are investigated on fragility functions of typical building structures. The study area is chosen as Eastern Turkey. The fragility functions are developed using site-specific uniform hazard spectrum (UHS). The site-specific UHS is obtained based on simulated ground motions. The implementation of ground motion simulation into seismic hazard assessment has the advantage of investigating detailed local site effects. The typical residential buildings in Erzincan are represented by equivalent single degree of freedom systems (ESDOFs). Predictive equations are accomplished for structural seismic demands of ESDOFs to derive fragility functions in a straightforward manner. To study the sensitivity of fragility curves to site class, two sites on soft and stiff soil are taken into account. Two alternative site amplification functions known as generic and theoretical site amplifications are examined for these two sites. The reinforced concrete frames located on soft soil display larger fragilities than those on stiff soil. Theoretical site amplification mostly leads to larger fragilities than generic site amplification more evidently for reinforced concrete buildings. Additionally, structural variability of ESDOFs is generally observed to increase the fragility especially for rigid structural models

Regional probabilistic seismic hazard assessment in Bangladesh

This presentation summarizes input data, procedures and results of probabilistic seismic hazard assessment (PSHA) in Bangladesh in the framework of the project ‘Geo information for Urban Planning and Adaptation to Climate Change’. It is a cooperation of the Geological Survey of Bangladesh (GSB) and the Federal Institute for Geosciences and Natural Resources (BGR) of Germany. The main aim of the project is to provide city planners with “Ground Suitability Maps”, which display different geo-factors. Seismic hazard is one of the geo-factors that contributes to these maps. For the derivation of “Ground Suitability Maps”, the influence of the local underground conditions will be taken into account additionally. A major part of Bangladesh is located in earthquake prone regions due to active tectonics. The Indian plate moves north-eastward towards the Eurasian plate at a velocity of about 6 cm/year. This motion leads to thrusting to the north (Himalaya) and to subduction to the east together with strike-slip mechanism. The thrusting and subduction processes have caused large historical earthquakes even inside Bangladesh (e.g. 1885 Bengal Earthquake M7 and 1918 Srimangal Earthquake M7.6). Therefore, it is crucial to assess seismic hazard in urban planning in Bangladesh. The input databases were compiled from the literature, reviewed and evaluated in this study. These are earthquake catalogs, the distribution of active faults and ground motion prediction equations. The most consistent and reliable databases were selected to be used in PSHA. The data of the earthquake catalog were declustered to eliminate the duplicated events, aftershocks and foreshocks. The spatial distribution of areal seismic sources was characterized using the distributions of earthquakes in the catalog and active faults. The completeness analysis of the earthquake catalog was performed and the Gutenberg-Richter magnitude recurrence distribution was derived for each seismic source. The results of PSHA are presented in the form of peak ground acceleration (PGA) maps with 10% exceedance probability in 50 years. As usual in regional PSHA, the results were compiled assuming bedrock as underground condition (so-called engineering bedrock with shear velocity of Vs30≥760 m/s). The northern and eastern parts of Bangladesh show the highest seismic hazard with PGA around 0.4 g with 10% exceedance probability in 50 years. This observation was expected because of the active tectonics in these parts.poste

Site-specific uniform hazard spectrum in Eastern Turkey based on simulated ground motions including near-field directivity and detailed site effects

In this study, stochastic earthquake catalog of the Erzincan region in Turkey is generated based on synthetic ground motions. Monte Carlo simulation method is used to identify the spatial and temporal distribution of events. Ground motion time histories are generated using stochastic simulation methodology. Annual exceedance rate of each ground motion amplitude is calculated through statistical distribution of the complete set of ground motions. The results are compared with classical probabilistic seismic hazard analysis (PSHA). Classical PSHA generally produces larger spectral amplitudes than the proposed study due to wide range of aleatory variability. The effects of near-field forward directivity and detailed site response are also investigated on the results