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The Effect of Vertical Excitation on the Response of Soil-Structure Systems Allowed to Uplift

Monir Vaghefi, Zeinab | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49293 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghannad, Mohammad Ali
  7. Abstract:
  8. The simultaneous effect of uplift phenomenon and vertical vibration of soil-structure system is investigated in this study. The super-structure is modeled as an equivalent single-degree of freedom with bilinear behavior mounted on a rigid foundation resting on distributed tensionless Winkler springs and dampers. The effect of vertical excitation on the response of soil-structure systems allowed to uplift is investigated parametrically through time history analysis for a wide range of systems subjected to sine pulse and a group of ground motions recorded on the soil type of C. The results consist of maximum displacement of the uplifting system and ductility demand of the super-structure as a part of soil-structure system. The ratio of each response of the uplifting system under both horizontal and vertical excitation to that of the uplifting system under only horizontal excitation is also calculated. These ratios indicate the importance of vertical excitation effects. The results of parametric study showed that vertical excitation increases the total displacement and ductility demand of super-structure. The importance of vertical excitation on the response of ordinary building-type structures is also studied by assuming a practical range of key parameters. It is observed that total displacement and ductility demand increases in different buildings. This effect on the total displacement of systems having different number of stories is almost constant. It is also observed that the effect of vertical excitation on the ductility demand increases with increasing number of stories. This means that the importance of vertical excitation is significant for slender systems allowed to uplift. This effect also increases with decreasing size of foundation, shear wave velocity and increasing strength reduction factor. In a word, the results indicate that inspite of before studies, the effects of vertical exciataion should be considered in analysis of systems allowed to uplift
  9. Keywords:
  10. Foundation Uplift ; Time History Analysis ; Soil-Structure Interaction ; Vertical Excitation

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