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Evaluation of Seismic Performance of Composite Moment Frame with Steel-Concrete Composite Column and Steel Beam Utilizing Fragility Curves

Salehi, Mohsen | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51470 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Bakhshi, Ali
  7. Abstract:
  8. The purpose of this research is to investigate the seismic behavior of plane moment resisting frame consisting of steel-concrete columns and steel I beams utilizing fragility curves. Due to the great influence of the column type in seismic performance of structure. To reach an optimal system, different types of steel-concrete composite columns has been used in the models and the fragility curve of each one is compared. Steel-Concrete composite columns can be divided into three types: (1) concrete filled steel tube (CFT), (2) steel reinforced concrete (SRC) and (3) new combinations of (1) and (2). Due to the abundance of the use of concrete filled steel tube (CFT) and steel reinforced concrete (SRC) in structures. In this study, focus on these two types of steel-concrete composite columns. Also because the plenty of urban construction, this research focuses on 5, 10 and 15-story frames and tries to use the fragile curves, which is one of the common ways to examine and compare various types of structural systems, to review and compare each of the systems in four following performance levels: (1) fully operational, (2) operational, (3) life safety, and (4) near collapse. In order to do this research, at first two-dimensional frames with different columns and elevations are modeled and then designed according to the relevant regulations, using Etabs. After designing the models, we developed a nonlinear dynamic analysis using open source software named Opensees. Then utilizing the Hunt-and-Fill algorithm to perform incremental dynamic analysis on the frames. Then, by processing the openness outputs, using the normal log distribution function, a program is written in MATLAB and the fragility curves of each frame are constructed based on two types of intensity measures: Peak ground acceleration (PGA) and spectral acceleration at the fundamental period of the structure (Sa(T1)) . Finally, the fragility curves of different frames in different functional levels are compared and it was determined that the composite frame framing system with concrete filled steel tube (CFT) column has better performance at all levels. After that composite moment frame with steel reinforced concrete (SRC) column stands in second place. And then steel moment frame stands in the last place in terms of performance. Also, between the two intensity measures, Peak ground acceleration (PGA) and spectral acceleration at the fundamental period of the structure (Sa (T1)), due to the less dispersion of responses in the dynamic analysis with intensity measure Sa (T1) than PGA. Spectral acceleration at the fundamental period of the structure found to has better function as intensity measure
  9. Keywords:
  10. Performance Based Design ; Fragility Curve ; Concrete Filled Steel Tubes (CFT) ; Reinforced Concrete Columns ; Composite Moment Frame ; Steel-Concrete Composite Column

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