Derivation of site-specific UHS based on simulated ground motions and its parametric effects on building fragility

Azari Sisi, Aida
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.
Citation Formats
A. Azari Sisi, “Derivation of site-specific UHS based on simulated ground motions and its parametric effects on building fragility,” Ph.D. - Doctoral Program, Middle East Technical University, 2016.