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Simulation of the Near-Field Earthquake Records without Velocity Pulse Using Stochastic Approach

Waezi, Zakariya | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48627 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofouei, Fayyaz
  7. Abstract:
  8. The necessity of providing synthetic acceleration records suitable for seismic assessment of the structures in the regions whose seismological history has not enough instrumental recordings has become one of the main concerns of the earthquake engineers. Despite being accurate in estimating earthquake ground motion, physics-based methods involve complicated procedures and need the detailed information about source, path and the site conditions of the scenario event which is not available for lots of engineering problems. The main goal of this dissertation is to introduce a novel stochastic method for the simulation of the non-stationary earthquake acceleration records compatible enough with the recorded accelerograms and its calibration based on the characteristics of the specific scenario event parameters. At first a short review to the general methods of ground motion prediction is provided and then the adequacy of Rezaeian and DerKiureghian’s method for stochastic simulation of the non-stationary ground motion is investigated. Then two new stochastic models DFM and NSMKT suitable for the simulation of near filed earthquake records are introduced. In order to determine the model parameters 4 compliance criteria including acceleration, velocity and displacement time history zero-crossings as well as the cumulative number of the positive minima /negative maxima are proven to be efficient and a few analytic equations relying the model parameters to theses 4 characteristics are developed. In order to calibrate the introduced models, for 252 near-field pulse-less records with strike-slip mechanisms, the optimum model parameters are estimated. Finally the regressive attenuation relationships relating the seismic parameters (including moment magnitude, rupture distance, shear wave velocity and the focal depth) to the optimum model parameters are developed and a stochastic method for the estimation of the model parameters according to the regressive equations is explained. At last the efficiency of the proposed method for the simulation of an ensemble of earthquake records corresponding to specific scenario event is investigated by Simulation of the non-stationary acceleration records using the DFM model and the regressive relationships for its parameters. The resulted ensemble median response spectrums are investigated against the corresponding values obtained from 5 NGA-WEST2 attenuation relationships and the results are discussed according to different scenario event parameters. The results indicate a proper compatibility between the simulated records' response and those recommended by NGA-WEST2 equations
  9. Keywords:
  10. Near-Field Earthquake ; Nonstationary Seismic Excitations ; Ground Motion Scaling ; Zero Crossing Detection ; Probabilistic Methods ; Ground Motion Simulation ; Time-Variant Linear System ; Negative Maxima/Positive Minima

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