4286

4057

كارشناسي ارشد

سازه

اصفهان : دانشگاه صنعتي اصفهان، دانشكده عمران

1387

يازده، 188، [II] ص. : جدول، نمودار

ص. ع. به: فارسي و انگليسي

امير مهدي حلبيان

23/7/1387

فياض رحيم زاده رئوفي، مرتضي مدح خوان

مهندسي عمران

ID4057

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

AbstractThe effect of foundation flexibility is generally ignored in seismic design of buildingstructures The design is commonly carried out on the results of static dynamic analysisconsidering fixed base condition But for building frames are embedded on soft soil thisassumption is not reasonable and seismic responses resulting idealized model are not identicalwith responses of realistic model The main objective of this research is to evaluate the effectof foundation flexibility on ductility demand of reinforced concrete frame structures Toachieve this goal a set of generic frame models with 5 story 10 story and 20 story height areused to evaluate seismic responses of R C frame buildings The generic models are idealizedas 3D frames using beam and column elements The nonlinear behavior of beam elements ismodeled by means of moment curvature theory Also in column elements multi axial springmodel based on material stress strain relation called fiber model is used to represent theinteraction among tension compression axial force and biaxial bending The effect offoundation flexibility is considered by substructure method implementing the concept ofimpedance functions of foundation So spring damper supports are used to represent soildynamic stiffness The story ductility demand is determined as the ratio of ultimate inter storydrift to yielding inter story drift Nonlinear time history analysis NTH is carried out toevaluate ultimate inter story drift To achieve this goal the foundation structure system issubjected to a set of ground motions The set consists of ordinary and near fault groundmotions Moreover nonlinear static pushover analysis NSP is carried out to achieve yieldinginter story drift The NSP load pattern is defined by lateral forces back calculated by responsespectrum analysis RSA of the structure assumed to be linearly elastic The results indicatethat soil structure interaction mostly increases the ductility demand of these types ofstructures Consequently it is necessary to consider foundation flexibility effects in structuraldesign of such building frames Also results demonstrate that story ductility demanddistribution over the height of the structure significantly differs among the various genericmodels and maximum ductility demand occurs in different stories Comparison among 1Dexcitation and 2D excitation of the generic models indicates that storey ductility demand of thestructure increases in generic models with 2D excitation This increment considerably dependson natural period lateral strength of the structure and frequency content of the near faultground motions

امير مهدي حلبيان

فياض رحيم زاده رئوفي، مرتضي مدح خوان