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Providing Design Spectrum for Iran Based on the New Generation of Ground Motion Model

Hajipour, Alireza | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56310 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Alijani Moghaddam, Hassan
  7. Abstract:
  8. Due to the inelasticity of the ground and geometric expansion, seismic waves are reduced by moving away from the center of wave propagation, which is called the attenuation of seismic waves. Therefore, the ground motions that occur at the site of the structures are different from the ground motions that are emitted from the source. The upcoming study investigates the attenuation of seismic waves in the geographical area of Iran based on the accelerogram data of Iran. Considering the consecutive occurrence of moderate to large earthquakes in Iran, the development of Iran's accelerography network, and the need to update the attenuation relationships by considering the parameters effective in the attenuation of seismic waves, it seems necessary to develop ground-motion models (GMM). Considering 2, 5 and 10% damping for the structure, this study will develop ground motion prediction equations (GMPEs) to estimate peak ground acceleration (PGA), pseudo-acceleration spectral values (PSA) and displacement spectral values (Sd) at 21 oscillator periods ranging from 0.01s to 4s. The displacement spectra considered in this research include elastic displacement spectra, displacement spectra with inelastic response potential and inelastic displacement spectra with constant resistance-to-weight ratios. Also, the adopted resistance-to-weight ratios include five ratios from 0.05 to 0.3. In this research, first, a catalog containing 659 records of 115 mainshocks that happened in Iran from 1976 to 2022 with moment magnitude greater than 5 is prepared, and then through the statistical analysis of mixed effect regression, taking into account the effects of nonlinear response of the site soil in the attenuation of seismic waves, the GMPEs are developed. The residuals of the proposed GMM are decomposed into three components, inter-event, site-to-site and event-site-corrected, and their distributions are examined against the predictor variables. The distribution of obtained residuals did not show any significant bias for the developed GMM. The output of this research is a GMM for Iran that can be used to estimate the elastic pseudo-acceleration spectra and the elastic and inelastic displacement spectra of records with magnitude 5 ≤ Mw ≤ 7.4 and epicentral distances from 0 to 200 km. Also, the proposed GMM of this research can be effective in design spectrum preparation, seismic zoning, and seismic risk and resilience analysis
  9. Keywords:
  10. Elastic Displacement Spectrum ; Inelastic Displacement Spectrum ; Design Spectrum ; Strong Ground Motion ; Iran Earthquake Catalog ; Pseudo-Acceleration Spectrum ; Ground Motion Prediction Equations

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