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Probabilistic Evaluation of Steel Moment Frames with Partially Restrained Connections

Zarei Rahmat Abadi, Davood | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49924 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Kazemi, Mohammad Taghi
  7. Abstract:
  8. Considering connections as ideally rigid or pinned is a common assumption during design and analysis of steel moment frames. However, in real world, steel connections show a non-linear behavior between these two ideal states. The aim of this research is to investigate the effect of partially restrained connections on the design and performance of two-dimensional steel moment frames under vertical and horizontal loads that are applied statically. For this aim, nonlinear finite element modeling is used in probabilistic evaluation process to assess the performance of existing structures. To capture the real behavior of structure in models, geometric and material sources of nonlinearity are considered. The probabilistic evaluation which leads to better understanding of the effect of uncertainty in model parameters is performed after the verification of modeled frames with available experimental results. Then reliability analysis is performed giving probabilistic distributions to the regarded loads and properties, indicating their effect on the performance of structure. Sensitivity analysis shows that initial rotational stiffness is the most important parameter used in connections’ moment-rotation models. In addition, to measure the effect of partially restrained connections during design period, an optimization procedure is implemented based on Modified Harmony Search algorithm. The total cost of frame is the objective function, considering a stiffness-based cost function for connections. Constraints of optimization consist of strength, serviceability and constructional compatibility limits stated in AISC LRFD design code. It was shown that the assumption of ideally rigid connections could be misleading during design and analysis procedures by underestimating the cost and capacity of different practical connections. Therefore, considering the real behavior of connections as partially restrained results in more accurate models and economic design
  9. Keywords:
  10. Optimization ; Reliability Analysis ; Probabilistic Assessment ; Nonlinear Analysis ; Steel Moment Resistant Frame ; Partially Restrained Connection

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