Dynamic soil-structure interaction

The dynamic response of a structure placed on a deformable soil medium subjected to seismic excitation is studied. The basic phenomena of soil-structure interaction was investigated by several analytical models supplemented by experimental observations; a brief review of literature in this discipline is also included. Among the physical phenomena investigated: the effects caused by local topography, the interaction -with other structures, and the dissipation of dynamic energy through the soil medium were described by exact series solutions. Foundations of arbitrary shape, however, were modeled by using an approximate integral representation. This latter method utilizes the principle of superposition and provides flexibility in analyzing numerically the three-dimensional disc foundations placed on the soil surface. The results indicate that the detailed description for the shape of a rigid foundation placed on a deformable soil medium is not essential in the overall response of the superstructure, but the stress distribution under the disc foundation is quite sensitive to these changes in detail. In this thesis, several methods for the calculation of foundation compliances for several types of foundation models were discussed, some of which have direct practical applications. The importance of the base input motion induced by incident seismic waves is also stressed, because the seismic input, along with the foundation compliances, are necessary for a complete analysis of this problem

“Comparative Study on Seismic Analysis of R.C Structure with Fixed and Spring Base in Different Zones and Soil Types Considering Soil Structure Interaction”

The nonlinear behavior of soil leads to complexity of a structure during earthquake. In recent trend soil structure interaction is considered only in very few cases and the structure is analyzed under the assumption of fixed or hinged base. Indian Standard Code also do not provide method for seismic analysis based on soil structure interaction since it has complication in analysis procedure. The response of a structure during earthquake is heavily influenced by soil structure interaction. In this study the comparative study on seismic analysis of RC frame structure with fixed and spring base in different zones of India are done taking different soil types and considering soil structure interaction. Two modes of soil structure interaction are considered for the analysis, one is replacing soil by spring and second by considering the whole soil mass. For the analysis purpose SAP 2000 software is used. For soil structure interaction study soil types considered are hard, medium and soft soil. Parameters such as displacement, drift and base shear are considered to determine the influence of soil structure interaction

Dynamic Soil Structure Interaction Study

The effect of the surrounding soil, as depicted by the soil-structure interaction effect, on the dynamic behavior of Brezina concrete gravity arch dam, located in El-Beyadh at the west of Algeria, is investigated in the present study. Both modal and transient analyses are performed for the dam, presented and discussed as a case study for this work. A three-dimensional finite element model (SOLID185) using ANSYS software is created to model the dam body and the adjacent soil. Three different seismic records having identical peak ground acceleration of 0.2g, assuming three different viscous damping ratios: 2%, 5% and 10%, are used in the analysis. The results of this analysis constitute a data base for a parametric study investigating the soil-structure interaction effect, that of the mass of soil foundation and that of the damping ratio on the dynamic behavior of Brezina concrete arch dam. Dynamic analyses for Brezina concrete arch dam for the three studied cases: dam without soil, dam with mass soil foundation and dam with massless soil foundation show that the presence of the soil in the model develops more stresses in the dam body, especially when the soil mass is considered in the model

Early history of soil–structure interaction

Soil–structure interaction is an interdisciplinary field of endeavor which lies at the intersection of soil and structural mechanics, soil and structural dynamics, earthquake engineering, geophysics and geomechanics, material science, computational and numerical methods, and diverse other technical disciplines. Its origins trace back to the late 19th century, evolved and matured gradually in the ensuing decades and during the first half of the 20th century, and progressed rapidly in the second half stimulated mainly by the needs of the nuclear power and offshore industries, by the debut of powerful computers and simulation tools such as finite elements, and by the needs for improvements in seismic safety. The pages that follow provide a concise review of some of the leading developments that paved the way for the state of the art as it is known today. Inasmuch as static foundation stiffnesses are also widely used in engineering analyses and code formulas for SSI effects, this work includes a brief survey of such static solutions

Significance of foundation-soil separation in dynamic soil-structure interaction

THe dynamic response of flexible surface strip-foundations allowed to uplift is numerically obtained for externally applied forces of a transient time variation. The soil medium is represented by an isotropic, homogeneous and linear half-space. The soil is treated by a time domain boundary element method, while the flexible foundation is treated by the finite element method. It was concluded that intermediate relative stiffness leads to moderate deformations when uplift is permitted. Very flexible footings produce higher deformations in unilateral contact compared to bilateral contact, and thus should be considered in their design. Unilateral contact does not significantly increase deformations for stiff footings subjected to concentrated central loading. However, relatively large deformation differences occur when the loading is eccentric, necessitating consideration of uplift in their design

Soil-Structure Interaction at the Waterfront

The Navy, forced by its mission to locate at the waterfront, often on loose, saturated cohesionless soils, faces a severe liquefaction threat. Research has been in progress to evaluate the Princeton University Effective Stress Soil Model. This paper discusses that model and presents a validation example study comparing model predictions with a centrifuge experiment