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Development of Seismic Fragility Curves for Reinforced Concrete Tall Buildings

Ansari, Mojtaba | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45693 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Bakhshi, Ali
  7. Abstract:
  8. This study focuses on the risk assessment of reinforced concrete tall buildings subjected to ground motion excitation. In order to assess the vulnerability of tall buildings, twelve-, and twenty-four-story four-bay reinforced concrete moment resisting frames are studied. This evaluation is done through developing fragility curves. These fragility curves provide the probability of exceeding the multiple damage states for a given intensity (e.g. CAV) of ground motion excitation. To develop the fragility curves, a great number of nonlinear dynamic analyses were conducted in the open-source platform OpenSees. Since the PEER Guidelines for Performance-Based Seismic Design of tall buildings (PEER, 2010) recommends to consider the effect of soil-structure interaction, SSI, in tall buildings using a response history substructure analysis of them, this study includes comparison between fragility curves of fixed base buildings and the ones derived from models considering the SSI effects to indicate whether SSI is beneficial or detrimental for such buildings. Uncertainties in structural characteristics are considered using Monte Carlo simulation and modeling different material properties as random variables. Former investigations show that considering uncertainty in soil properties such as friction angle, cohesion, density, shear modulus and Poisson's ratio makes a negligible difference in seismic demand, so we pass up this uncertainty. Four sets of seven earthquake accelerograms corresponding to type C & D soils (based on NEHRP classification) for far and near sources were selected to be used in the analysis. Finally the developed fragility curves can be used to assess the tall buildings behavior during earthquakes and discern the effect of SSI, height of structures and soil type on seismic response of this type of structures. An increase in the probability of exceedance of different damage states is observed in the cases of considering SSI effects, type D soils and near-source accelerograms
  9. Keywords:
  10. High Buildings ; Soil-Structure Interaction ; Damage Index ; Fragility Curve ; OpenSees Software

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