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Quantification of the Seismic Design Coefficients for Low to Mid-Rise Composite Special Moment Frames with Reinforced Concrete Columns and Steel Beams

Tavasoli Yousefabadi, Elmira | 2024

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  1. Type of Document: Ph.D. Dissertation
  2. Language: English
  3. Document No: 57870 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Kazemi, Mohammad Taghi
  7. Abstract:
  8. This study investigates the performance of the Reinforced Concrete column and Steel beam (RCS) structural system at the system level, with a focus on evaluating seismic design coefficients (R-factor, Ω₀, and Cd) using FEMA P-695 methodology. The RCS system provides a more efficient alternative to conventional steel and reinforced concrete moment-resisting frames, offering higher damping and lateral stiffness in RC columns along with greater energy dissipation in steel beams. Although several studies have examined the RCS system's performance, most have concentrated on the connection level. In this study, 32 archetypes are designed with variations in building heights, span lengths, concrete strengths, and load levels. Nonlinear numerical models are developed and validated through five experimental tests, then subjected to static pushover and response history analyses. The seismic design coefficients are evaluated and discussed following FEMA P-695 methodology. The findings indicate that the RCS system's design is efficient, providing a high safety margin. However, the level of conservatism is found to be overly high, suggesting that a larger R-factor or more relaxed design requirements could be considered. The study demonstrates that an R-factor of less than 10 ensures adequate safety under seismic loading. Additionally, the research explores the impact of different generations of ASCE guidelines on connection performance. Four specimens are analyzed: two designed according to the earlier ASCE guideline and two based on the updated version. A validated finite element model reveals that connections adhering to the earlier guideline exhibit better performance. The inclusion of a 6 mm thick doubler plate and triangular stiffeners significantly enhances connection performance, with minimal cost impact, increasing energy dissipation capacity by 25.5% and reducing strength deterioration during cyclic loading by 40%
  9. Keywords:
  10. Composite Structures ; Earthquake Engineering ; Nonlinear Modeling ; Special Moment-Resisting Frames ; Seismic Design ; Federal Emergency Management Agency (FEMA)P695 Code

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