Estimation of Displacement Modification Factor for Soil Structure Systems with Embedded Foundation Structures and Stiffness Degradation Hysteresis Models

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Izaddoust, Ali | 2013

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 44084 (09)
University: Sharif University of Technology
Department: Civil Engineering
Advisor(s): Ghannad, Mohammad Ali
Abstract:
The effect of soil structure interaction, on displacement modification factor in constant reduction factors (CR) is evaluated, studied for SDOF structures placed on flexible base modeled by 3DOF system as the base foundation (a sway, a rocking and an internal degree of freedom to see the frequency dependency of dynamic stiffness of soil). 60 records of FEMA-440 for 3 types of soils (B, C and D) are analyzed for 28 different soil-structure conditions, 6 different level of reduction factors, and varied secondary hardening for 2 different hysteresis behavior to see the effect of stiffness hardening. Results are plotted in spectrums to see the role of Tn.
Final results show that effect of reduction factor and positive secondary hardening are the same as structures placed on rigid base and effect of different hysteresis behavior, reduces by increasing of reduction factor. Although, for long periods, CR spectrums show a constant value (=1), but for Tn, less than 1.5 seconds, we could see the values are so large and highly dependent to Tn , base soil, reduction factor and specially difference in soil structure interaction
Keywords:
Inelastic Behavior ; Displacement Modification Factor ; Stiffness Degrading Model ; Possitive Secondary Stiffness Hardning ; Based Soil ; Cone Models

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