Nonlinear Analysis On The Torsion Coupling Seismic Behavior Of Soil-asymmetric Structure Interaction System

Nowadays building structures present more and more complex. When the centerof mass and the center of stiffness on the floor don’t coincide in a point，buildingstructure will show lateral and rotational coupling reaction under seismic loads.Equivalent static method and Torsion coupling response spectrum method are oftenadopted to analysis horizontal and vertical irregular structure in anti-seismic codes ofvarious countries, according to the principles of SRSS or CQC method to calculateseismic response of eccentric structure under horizontal seismic. These analyticalmethods are all used in elastic stage, but the study of eccentric structure inelastic—plastic stage is still infancy because of existing difficulty in bothexperimental research and computational analysis.Subsoil characteristic will have notable impact on eccentric structure. Nowadayssubsoil is usually treated as rigid foundation, but soil rigidity will be different fromthe actual situation. Therefore in order to improve the level of anti-seismic design, itis greatly concerned and necessary to carry out the research on law of seismicresponse about Soil–eccentric Structure Interaction.In this paper, eccentric structure of single floor considering Soil–StructureInteraction is adopted to analysis to establish dynamic equation and getting dynamiccharacteristic parameters——eccentricity ratio、torsional translation frequency ratio、influencing parameters of Soil–Structure Interaction.The upper eccentric structure is simplified as a modal of three anti-lateral forcemembers and by optimizing, the modal can be fit nonlinear analysis. The lower part ofSoil–Structure Interaction is simulated by ANSYS to get the restraint stiffness——Lateral stiffness、Torsional stiffness, substituted by spring.At last, the eccentric modal of rigid foundation and considering Soil–StructureInteraction are used to analysis by MATLAB software and pushover method and therelative conclusion of dynamic characteristic parameters variation can be got.New view and new method of investigating the whole process that the dynamiccharacteristic of structure changes is used to research dynamic characteristicparameters of eccentric structure considering Soil-Structure Interaction, entirelyanalysising the elastic and elastic-plastic stage of the structure, thus it providesimportant theoretical basis for enriching anti-seismic code.