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Risk-Based Seismic Design of Buildings in the Context of Cities,with Rigorous Uncertainty Modeling, and Proposing Efficient Computational Methods

Ghods, Babak | 2022

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 55657 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofooei, Fayaz
  7. Abstract:
  8. The main goal of the current building design codes is to protect life safety, and generally, they do not directly address other societal, economic, etc., concerns regarding earthquakes. However, recent earthquakes around the world have shown that the effects of earthquakes' damages and losses can go beyond life-safety concerns. This observation has led many renowned scholars, organizations, and agencies to state the need to change the current design codes. In this regard, this thesis investigates the basis of setting the seismic design requirements and suggests a method in this respect. The study consists of two main parts. Part I (theory and design methodology) discusses some theoretical and conceptual issues of risk-based/informed decision-making about the seismic design of structures. Then, based on this discussion, a process for determining the minimum seismic design requirements (MSDR) is proposed. Compared to more common methods for determining MSDR, the suggested process differs in two aspects. First, the determination of MSDR is not only concerned with the performance of individual buildings but also the regional seismic performance. Therefore, this method determines the MSDR of different buildings (with different occupancies and structural systems, etc.) in a way that satisfies both the building-level and regional-level goals of the decision-makers in any region/city. The second important aspect of the method is the emphasis on rigorous modeling of uncertainties in seismic risk assessment and determination of MSDR. The proposed process utilizes the FEMA-P58 methodology for the seismic performance assessment of the buildings. Considering that using the proposed method at different places with different seismic characteristics could be very time-consuming, in part II of the study (increase in computational efficiency), two computational methods are proposed that help the implementation of the proposed process in part I. In this regard, a method is proposed for site-specific assessment of structural responses (e.g., the collapse fragility curve) that uses a combination of the Bagging algorithm and the site-specific record selection methods. Also, the performance of several mean-covariance regression methods is investigated for more efficient estimation of EDP|IM distributions. Utilizing these regression methods along with the proposed method with the Bagging algorithm leads to an efficient process for assessment of structural responses (necessary for FEMA-P58 methodology and consequently the proposed method in part I) at different locations
  9. Keywords:
  10. Uncertainty ; Seismic Hazard Analysis ; Regression Analysis ; Seismic Design ; Bagging ; Regional-Based Seismic Design ; Risk-Based Seismic Design Decision Making ; Ground Motion Record Selection

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