Studies on Seismic Safety of Structure-Soil Interaction System and Its Rational Design Procedures

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This study aims at getting useful information for design of extended large scale civil engineering structures through the analysis of such structures with emphasis on dynamic soil structure interaction. The following issues has been focused :(1) Wave propagation in the soil deposit with the local topography(2) Dynamic soil-structure interaction and the foundation impedance and the effective input motion(3) Nonlinear soil effect in strong earthquake motion on structural response(4) Progressive input motion to multiple input structuresTopographical study of the construction site is made to investigate the seismic wave amplification in 2 dimensional sense. The frequency domain analysis, the time domain analysis and their hybrid approach have been employed. The parameter used are the incident wave types, angle of incidence, topography, aspect ratio between wide and depth of the soil deposits. Analysis is conducted for representative nondimensional frequency as defined by the surface width … More of the deposit and the incident wave length. Soil amplification due to the local topography depends significantly on the wave type and noodimension frequency.The Green function involved for the BEM analysis is developed for the concentrated as well as uniform distributed forces. The Fourier transform method needs the wave number integration for the inverse transform. This is performed by the Gauss quadrature and by the modified Clenshaw-Curtis method. The Green function for multilayer makes it possible to perform the soil deposits with layered half space. Detail discussion is made for the offset of source forces in the indirect boundary element method. The time domain analysis used the Cgniad-de Hoop method for the analytical solution for a full plane.Group pile foundations are constructed on soft soils to support superstructures. The present analysis took deliberate consideration for the pile-soil-pile interaction. The substructure method is used to advantage, splitting the soil and piles. The soil analysis is performed by use of the thin layer method. The pile analysis is made from the mass discrete system and the mass distributed system. The investigation is focused the pile head impedance function. The simulation is carried out for a single pile loading test.The investigation for rigid buried foundations is also executed with interest to soil layering, the interaction between adjacent foundation through soil, fillback effect.Soils in strong ground motion attain high strains, indicating heavily nonlinear behavior with drift of the base line for the nonperiodic seismic input. Assuming certain stress-strain relationship, response computation are made for the 1-dimensional and the 2-dimensional models by the direct step-by-step integration scheme and by the equivalent method based on effective stain. The results are compared for the time histories and the response spectra. The difference of modeling and the characteristic of nonlinearity are clarified. The importance of the 2-dimensional modeling is emphasized in order to interpret the recorded data.Pile supported structural response with nonlinear soil properties is investigated, together with the equivalent linear analysis. Soil-deformation is based on the assumed soil stress-strain characteristic. Although the equivalent linearization technique predicts reasonably the truly nonlinear response, the difference between these responses becomes appreciable as the input motion grows. Especially, such nonlinear structural response gives rise to reduced acceleration but amplified displacement. Less