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Influence of Soil-Structure Interaction on Collapse Margin Ratio

Asgarpoor Khamneh, Masoumeh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50352 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghannad, Mohammad Ali
  7. Abstract:
  8. This thesis reveals the influence of soil-structure interaction (SSI) on the collapse potential of structures and also investigates the change in collapse margin ratio (CMR) of structures for which the design base shear has been reduced based on the soil-structure interaction provisions. According to the properties of structures and seismic excitations, SSI can increase, decrease or make no change in the response of structures. Based on seismic design codes for fixed-base structures, SSI causes reduction in design base shear of buildings. These provisions are based on linear behavior of structures. But under strong ground motions, specially at collapse level, structures can experience strong nonlinear behavior. So it is more likely that these regulations change performance of soil-structure systems such as CMR in comparison with fixed base structures. For this evaluation, three systems have been studied. A fixed base structure, a flexible base structure and a flexible base structure with reduced design base shear. SSI provisions of both ASCE/SEI 7-10 and 2015 NEHERP standards have been studied to investigate the change of CMR. In this thesis the model is an one degree of freedom structure with softening in force-deformation diagram located on shallow foundation. Also dynamic stiffness of soil depends on the frequency of excitation. CMR of three type systems with bilinear model have been calculated using instructions of FEMA-p695 and incremental dynamic analysis method. Results show that SSI increases CMR in most cases. Also reduction of design base shear causes an increase in the collapse probability of structures. 2015 NEHRP regulations improve the performance of soil-structure systems at collapse level in comparison with ASCE/SEI 7-10 seismic provisions
  9. Keywords:
  10. Soil-Structure Interaction ; Incremental Dynamic Analysis ; Collapse Margin Ratio ; Nonlinear Behavior ; Collapse Analysis

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