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Simulation the Near-Fault Velocity Pulses from Form and Intensity Point of View

Waezi, Zakariya | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39874 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofooei, Fayaz
  7. Abstract:
  8. Near-Field earthquakes have gained so much attention through their catastrophic consequences on structures in the vicinity of seismic sources during recent events. Based on recorded data, it is understood that these kinds of phenomena are often accompanied with a large energy pulse at the first times of record whose impulsive characteristic is primarily caused by “forward directivity”. Incapability of response spectra for depicting great demand for energy dissipation disqualifies this method for utilization. Thus it seems inevitable to analyze the models prone to this kind of hazard using time-history based analysis. Being simple enough in time domain, raises hopes for finding a mathematical representation of seismic ground motions that can simplify analysis and design procedure, especially by reducing required analysis time. In this thesis, Authors intended to assess some models that have been utilized so far by other investigators and introduce more suitable representation for wider range of source-site conditions. Some common methods of artificial records like Kanaii-Tajimi model have been found unsuitable for generating quakes of near-fault type. However Papageorgiou pulse as one of the most practical models to represent pulse-type motions is focused on and its practical pitfalls in simulation of original records are discussed. A novel model based on Gaussian function is introduced whose best convergence in “least square” algorithms of curve fitting makes it more preferable than Papageorgiou’s. To simulate the residual part of earthquakes which is defined by extraction of pulse from original record, a closed form equation for the FFT transform of each residual is fitted and a time domain function is generated. Finally synthetic records constructed from combination of Papageorgiou pulse with background record are examined against correspondent original records and the required parameters are calculated.

  9. Keywords:
  10. Near-Field Earthquake ; Velocity Pulse ; Pulse Shape ; Background Earthquake

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