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Investigation the behavior of Low-Rise Shear Walls with Smart Rebars

Piran Aghl, Payam | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39659 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khaloo, Alireza
  7. Abstract:
  8. In this paper, the response of low-rise shear walls with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is Shape Memory Alloys (SMAs) which contains nickel and titanium elements. During lateral loading, rebars yield or concrete crushes in compression zone in some parts of the RC shear walls and also residual deflections are created in the structure. The SMA exhibits little residual strains under cycles of loading and unloading even after passing the yielding zone. In addition, SMAs have a good energy dissipation capacity that helps reduce damage while increasing structural capacity. In this study, SMA rebars were provided in diagonal direction (from the top corner to the bottom corner of the wall). This type of arrangement is because the diagonal reinforcement configuration was found to form a more effective shear resisting mechanism, resulting in higher energy dissipation capacity and less stiffness degradation with displacement reversals. The amounts of steel ratio in both perpendicular directions of the shear walls have been reduced in order to replace with diagonal smart rebars. Since Young's Modulus of this material is much lower than that of conventional steel reinforcement, it is not feasible and economical (due to relatively high price of shape memory alloys) to replace the total steel with SMA bars. The behavior of these shear walls has been compared with that of ordinary RC shear walls designed according to ACI318 code. A parametric study has been conducted and the effects of strength of concrete, loading amplitude (level of shear wall top displacement), and ratio of smart rebar on the cyclic response of the low-rise shear walls have been investigated. It is found that by using SMA rebars in RC shear walls, these materials tend to return to the previous state (zero strain), so they reduce the permanent deformations and also in turn create forces known as recovery forces in the structure which lead into closing of concrete cracks in tensile zone. This ability makes special structures to maintain their serviceability after earthquake. It was also observed that the maximum shear strengths of the shear walls are affected by SMA rebars. Besides, using diagonal SMA rebars will lead to decrease the amount of residual displacement without decrease in the energy dissipation capacity of the low-rise shear walls. Moreover, in each model the amount of stiffness reduction and its effects have been studied.
  9. Keywords:
  10. Shape Memory Alloy ; Smart Rebar ; Permanent Displacement ; ANSYS Software ; Shear Walls

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