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Risk-based Approach to Account for Soil-Structure Interaction in Seismic Design of Building Structures

Vaseghi Amiri, Shaghayegh | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53393 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghannad, Mohammad Ali; Mahsuli, Mojtaba
  7. Abstract:
  8. This paper proposes a novel probabilistic approach to account for soil-structure interaction (SSI) in the seismic design of building structures. In this approach, an SSI response modification factor, RSSI, is introduced to capture SSI effects on the seismic performance of structures. The proposed procedure quantifies RSSI such that the probability distribution of the collapse capacity of the structure designed to account for SSI concurs with that of the structure designed using the default fixed-base provisions. The proposed approach is employed for special steel moment frame buildings with surface foundation. A surrogate single degree of freedom (SDOF) system is developed in this study and employed to model the nonlinear behavior of the structure. The developed surrogate SDOF model can be utilized to estimate the probability distribution of the roof drift ratio of multistory buildings at various ground motion intensity measures. The surrogate SDOF model generated herein explicitly accounts for model uncertainties. The properties of the surrogate model are computed using a probabilistic function of the fundamental period of the structure developed using Bayesian linear regression. To validate the surrogate model for SMFs, the results from inceremental dynamic analyses using detailed multistory SMF models are compared with those of the corresponding surrogate SDOF models. The results indicate that no reduction in the design base shear is advisable for structures located on moderately soft to firm soils with shear wave velocities above 150 m/s. This conclusion is at odds with the current prescription of SSI provisions of seismic design code, which allow some reduction in the design base shear for such buildings. A thorough assessment of the design base shears obtained through current codified SSI provisions reveals a nonuniform risk of collapse for different soil-structure systems. In comparison, the median RSSI values computed through the proposed approach lead to a uniform risk of collapse and can be considered for the seismic design of special steel moment frames
  9. Keywords:
  10. Soil-Structure Interaction ; Risk Analysis ; Steel Special Moment Frame ; Seismic Design Codes ; Single Degree of Freedom Structures ; Collapse Analysis ; Linear Bayesian Regression ; Buildings Design

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