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Development of Fragility Curves for a Number of Existing Buildings in Qazvin

Soltanieh, Hamideh | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48547 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Bakhshi, Ali
  7. Abstract:
  8. The objective of this study is to assess seismic vulnerability and more specifically to develop analytical fragility curves for a number of existing buildings in Qazvin. Fragility curves represent exceedance probability of the structural response from a specific limit state at a given seismic intensity level. In this study, Maximum Interstory Drift Ratio and Spectral Acceleration at fundamental period of the structure with 5% viscous damping are considered as Damage Index and Intensity Measure, respectively. Limit states are also applied as it is suggested in FEMA 356. In order to obtain comprehensive and extensible results as far as possible, the type of buildings under study must be selected in such a way that it comprises the majority of the statistical population. For this purpose, the type of the structural system under study is chosen using the obtained information from both Qazvin Statistics and IT organization and Qazvin Construction Engineering Organization. 40 three to seven story residential steel structures designed between 1389 and 1394, with hinged connections and bracing system in two directions are modeled Three-dimensionally in OpenSees, accordingly. To model buckling behavior of the braces, the proposed model by Uriz and Mahin is used. Since the random nature of earthquake has been defined as the most significant source of uncertainty in probabilistic assessment of structures in many studies conducted previously, in this study uncertainties arising from variability of material properties are not accounted for directly. Since these uncertainties (although insignificant) are effective in obtaining real results, they can be applied as quantitative values at the end of the analyses. As a result, FEMA P 695 guideline is used in this study to quantify total uncertainties. In order to analyze the models, Truncated Incremental Dynamic Analysis with 〖IM〗_max=2g and a step equal to 0/2g has been used. Far-field record set has been applied as it is introduced in FEMA P695. This record set contains 22 pairs of horizontal components of earthquake on site soil type C and D on the basis of NEHRP classification. Fragility function is defined as a log normal cumulative distribution function and maximum likelihood method is used to estimate the fragility parameters. In the end, IDA and fragility curves for all models are listed. According to the curves obtained it can be seen that seismic vulnerability of structures generally increases as the number of stories increases. Concentration of the inelasticity is also found to be mainly in the first story level
  9. Keywords:
  10. Seismic Vulnerability ; Fragility Curve ; Fragility Analysis ; Incremental Dynamic Analysis ; Braced Steel Structure ; Truncated Incremental Dynamic Analysis

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