Dynamic soil-structure interaction analysis

DYNAMIC SOIL-STRUCTURE INTERACTION ANALYSIS SUMMARY Keywords : Soil-Structure Interaction, Consistent Infinitesimal Finite Element Cell Method, Free-Field Motion, Dynamic Analysis In this study, a new numerical procedure is proposed for the analysis of two- dimensional dynamic soil-structure interaction. The interaction force-displacement relationship is calculated by using the consistent infinitesimal finite element cell method. Assembling the interaction force-displacement relationship of the unbounded soil medium with the equation of motion of the structure leads to the basic equations of the total dynamic system. As a result, irregular bounded medium material inhomogeneities can be processed and nonlinearity of soil can be consistently taken into account. To verify the studies, a two dimensional, plain strain, soil structure interaction system is solved in time domain. The analysis procedure performed in three steps as; first, seismic free-field input motion along the interaction horizon is determined. This is achieved by the analysis of unexcavated virgin soil in the absence of the structure. Then, assuming the far-field to be linear, dynamic boundary conditions along the interaction horizon are defined by calculating the unit- impulse response matrix of the far-field in time domain. In the third step, the analysis of the soil structure system under the action of free-field input motion determined in the first step, subject to the dynamic boundary conditions determined in the second step, is carried out. The results obtained are; (i) besides the geotechnical nature of the soil and dynamic structural properties, the random characteristics of the earthquakes may be an important contributing factor in soil structure interaction analysis; (ii) for the extremely stiff and stocky buildings constructed on relatively soft soil conditions, the calculated relative displacements and base shear forces are greater in values than the fixed-base structural systems; (iii) the building aspect ratio plays a key role in soil structure interaction effects; and (iv) as the shear wave velocity of the soil medium increases, the effects of soil-structure interaction considered beneficial for seismic response of the structures. XXVIII