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Evaluation of the Cyclic Performance of Buckling Restrained Braces with Sliding Friction Connection

Yazdani Kachoie, Pedram | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 54571 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Mofid, Masood
  7. Abstract:
  8. In today’s world, the use of lateral load-bearing systems, such as bracings, has become a pretty common practice. Often showing axial deformation behavior, these members exhibit proper performance under tensile loads but tend to become unstable under compressive loads. In contrast to common bracing systems, the buckling-restrained bracing (BRB) systems perform well under not only tensile loads but also compressive loads. Recent studies have paid greater deals of attention to the application of short-core BRB systems in different structures. The bracing core has been shortened to increase the core deformation and hence the energy dissipation capacity of the bracing system. In this condition, due to the increased deformation of the core, a very low cyclic fatigue failure mode would establish, which results in deterioration of the energy dissipation load-bearing capacity of the bracing system. This indicates the necessity of controlling the core deformation to prevent its failure. Some research works have used a combination of Pall friction dampers (PFDs) with bracings, in series, to enhance the energy dissipation capacity and improve the overall system performance. This has been while mixed application of the PFDs with BRB systems has been proven economically inefficient.Therefore, the present research introduces a simple slip joint with friction plates coupled, in series, with a short-core all-metallic BRB system. For this purpose, once finished with validating the numerical model against a prototype of the short-core BRB system, eight different instances of the proposed system were simulated to evaluate their cyclic behavior, dissipated amount of energy by different members, and stress and strain distributions along the core length. We further investigated other parameters, including bolt prestressing force and type of holes into the friction plates. Next, the best and worst instances were subjected to AISC-341 loading scheme to discuss whether they can or cannot meet the requirements set by the standard code. The results showed that the friction plate slippage decreases with increasing the bolt prestressing force, so that the BRB core undergoes rupture at significantly smaller deformations. On the other hand, a decrease in the bolt prestressing force was seen to increase the friction plate slippage, thereby adding to the energy dissipation capacity of the system. The use of larger holes provided for further slippage of the friction plates and hence the dissipation of larger amounts of exerted energy. In this instance, failure of the short core of the BRB system was hindered although no PDF was incorporated into the structural system. That is, at a given cost, we could not only improve the energy dissipation capacity of the system but also control the core deformations
  9. Keywords:
  10. Cyclic Behaviour ; Buckling Restrained Braces Frame (BRBF)System ; All-Metallic Buckling-Restrained Short-Core Bracing ; Resilient Slip Friction Joint (RSFJ) ; Sliding Friction ; Bolt Prestressing Force

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