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Rehabilitation of Reinforced Concrete Frames using Ductile Bracing Systems

Hadei, Mehdi | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39336 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Kazemi, Mohammad Taghi
  7. Abstract:
  8. In this thesis, the nonlinear seismic behavior of typical Iranian building is evaluated. The evaluation results indicated that these building, which were designed, based on first edition of 2800 standard and before, due to ductility and stiffness deficiency, don’t satisfy the 3th edition of 2800 standard and FEMA356 requirements, then retrofit of the most old structures is recommended. Selected samples include ordinary moment resistant concrete frames. The effectiveness of three retrofit schemes, concentric steel bracing (CBF), Eccentric steel bracing (EBF) and buckling restrained bracing, are studied and compared. The results of investigation indicated that although CBF retrofit scheme is efficient in stiffness increases and lateral displacement reduction, but because buckling of braces in compression, strength and stiffness of structure suddenly decrease and structure has not ductile behavior. In addition, this scheme of retrofitting cause to increasing the internal forces of braced columns, which due to limit in capacity of these elements, strengthening of these elements unavoidable. Therefore these scheme may be does not satisfy the retrofit objectives. In retrofit method with eccentric braces due to localize the plastic deformation in the link beams and braces remaining elastic, have more ductile behavior compare with CBF, but increasing of stiffness and strength of structure are lesser. In retrofit method with buckling restrained braces duo to no buckling of braces in compression and braces yield before reach to buckling load, strength, stiffness and ductility increasing more than two mentioned method and structure has good seismic performance. In addition, results show that BRB braces is more efficient for high-rise building retrofitting than small buildings
  9. Keywords:
  10. Seismic Rehabilitation ; Concrete Building ; Buckling Restrained Braces Frame (BRBF)System

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