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Effects of Stiffness Distribution on Demand Reduction in Elastic MDOF Structures

Ghaedizadeh, Arash | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 39670 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Karami Mohammadi, Reza
  7. Abstract:
  8. The present research illustrates the Effects of Stiffness Distribution on Demand Reduction in Elastic Multi Degree Freedom Structures. The structural configuration of a structure has an important effect on dynamic performance of it and its nonstructural contents. For equipment, the displacement or acceleration demand is defined in terms of the input motion applied at the appropriate attachment point(s) of the equipment. This demand or input motion is generally represented by an in-structure response spectrum (IRS). The IRS will differ significantly from the design base earthquake (DBE) spectrum because it is essentially filtered and/or amplified through the building. To assess the realistic dynamic behavior of the equipment, the demand at the attachment point(s) of the equipment must consider the effects of structural filtering and/or amplification. Consequently, equipments and nonstructural elements in structures with inappropriate distributions of stiffness have performed poorly in recent earthquakes, and most of the observed collapses have been related to some extent to structural configuration problems. Different types of stiffness distribution are responsible for a deficient structural and nonstructural behavior. Concentrated drift and acceleration in some stories are the worst type and could result in catastrophic consequences. The question that arises is “how the lateral stiffness pattern of multistory buildings should be modified to ensure that the required demands especially in equipments and nonstructural elements are the minimum yet in the elastic range?” The main objective of this research is to address this question. The results can be utilized for inelastic range of seismic structural behavior .Finally; a statistical investigation has been executed to obtain probability of exceedance of any special floor acceleration in shear building structures designed in accordance with Iranian Code for Seismic Resistant Design of Buildings. (ISIRI 2800)
  9. Keywords:
  10. Multi-Degree of Freedom Structures ; Hardness Distribution ; Optimum Distribution ; Seismic Response ; Nonstructural Elements

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