تحليل پديده ي اندر كنش غير خطي خاك و سازه در سازه هاي بتن آرمه به كمك يك مدل سطح مرزي خاك

چكيده انگليسي :

Nonlinear Soil Structure Interaction in R C Frame Structures Using a Bounding Surface Constitutive Soil Model Mehrdad Alizadeh m alizadeh@cv iut ac ir Date of Submission 2012 04 25 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Mahdi Halabian mahdi@cc iut ac irAbstractThe effects of the structure s surrounding soil layer on the seismic response of the structure are investigatedfor decades Most of the researches related to the soil structure interaction SSI have been conducted withlinear or at most equivalent linear assumption of the soil layer behavior Considering nonlinear soil behaviorand its effects on the seismic response of the total system is almost a new researching field relating to SSIand is known as nonlinear soil structure interaction The nonlinear soil behavior influences on both the free field response and the soil structure interaction in a complex way In this study employing a new plasticitymodel developed for simulation of monotonic and cyclic behavior of sandy soils the effect of nonlinear soilbehavior on the elastic and inelastic response of a set of 5 10 and 20 story R C generic frame model isconsidered and compared with linear behavior of the soil layer The modal pushover analysis MPA methodwas used to consider inelastic behavior of structures and nonlinear time history method to analyze soil structure system which after conducting MPA analysis is a one degree freedom structure reflecting modalcharacteristic of the mulistory structure supporting on the flexible foundation MPA method is generallyrecognized as a new analysis method for estimating fixed supported structure demand with capability toinclude higher mode effects on response Many prior researches were conducted to consider possibility andability of MPA method in SSI problems By using MPA approach to analyze structures supporting onflexible foundation the effect of the foundation flexibility on the load distribution which is used to pushsystem in each mode will be involved The constitutive model used for considering nonlinear soil behavior was presented by Dafalias and Manzari 2004 They proposed the model as a bounding surface model based on the state parameter of soil Formulation of the model is based on stress ratio and states that just change in value of stress ratio result indeviatoric plastic deformation The volumetric plastic deformation is related to the deviatoric plastic strain bydilation parameter defined using Rowe s dilatancy theory Using plasticity theory consistent with the criticalstate framework and by usage of state parameter this model provides a nonlinear constitutive model whichcould predict nonlinear monotonic and cyclic response of soil almost accurately The nonlinear behavior ofthe structures was modeled using moment curvature relations for beam elements and fiber element methodfor columns Fiber elements could consider inelastic behavior of a member using multi axial springfollowing nonlinear stress strain relation of materials assigned to the section of the member By using thismethod moment axial load interaction of the columns will include automatically To consider soil stratumstiffness effects on the seismic response of frames three types of the soil layer with 150 250 and 500 m sshear wave velocity of soil halfspace were selected The analysis was conducted for five near fault groundmotions Results are presented as response spectra for three types of generic frames with both elastic andinelastic behavior as well as linear and nonlinear soil behavior and also all type of soil layer Foundationrocking and its effects on the seismic response of the structures was another aspect of this study Keywords nonlinear soil structure interaction bounding surface soil model modalpushover analysis response spectra

علي زاده، مهرداد

تحليل پديده ي اندر كنش غير خطي خاك و سازه در سازه هاي بتن آرمه به كمك يك مدل سطح مرزي خاك

تحليل مودال پرش آور , رفتار غير خطي خاك