Papers by Keyword: Soil-Structure Interaction (SSI)

Abstract: In this paper we shall deal with application of analytical and numerical calculation methods in selected geotechnical problem. It is well-known that numerical modeling by Finite Element Method (FEM) is often used for solving complicated engineering problems. FEM is very universal and efficient tool for their solution. In our case a contact task of rigid shallow (circular, rectangular and strip) foundations loaded by centric force, has been solved. The obtained results of vertical normal stresses distributions according to analytical methods and FEM solutions have been analyzed and mutually compared. Results of the calculations have been presented in graphical and tabular form, too.

Abstract: Most of ancient pagodas were damaged by earthquakes, and the dynamic behavior is a key factor to determine the seismic strengthening scheme of the pagodas. This research selected a typical masonry pagoda as the object, combined free vibration test with numerical simulation to discuss the influence of dimension change of ground base on dynamic behavior of the pagoda, as well as the construction method of the FEA model based on the soil-structure interaction. The dynamic behavior tested from a 1:15 reduced scale of physical model indicated: comparing with the condition of pagoda pedestal is fixed, the natural frequency of the superstructure is decreasing with the increase of thickness of ground base，which shows the “soft effect” of ground soil to structural stiffness. The influence degree of thickness and plan size of ground base to dynamic behavior of the physical model are simulated by program ANSYS, and the effective dimension range of ground base for the FE analysis of pagodas has been proposed.

Abstract: Based on the double member model of wall-frame structure and the corresponding transfer matrix method, the concept of frequent impedance of rigid foundation is introduced so that SSI can be taken into account. This method is more convenient and efficient compared to finite element method because of fewer structural parameters and faster calculation speed. Necessary structure parameters include 7 parameters of each storey, geometry size and total mass of foundation and elastic parameters of site soil. Totally 39 examples were calculated for 13 values of foundation mass and 3 kinds of soil, which are compared to the result of fix bottom model of upper structure. Results show that SSI does not always deduce a decrease of seismic response. Sometimes SSI may increases structural displacement evidently. The simplified method would provide structure designers an efficient tool to understand seismic behavior of wall-frame structures with various foundation and site soil.

Abstract: For decades attention has been paid to interaction of foundation structures and subsoil and development of interaction models. Currently there are several software that, can deal with the interaction of foundations and subsoil. The purpose of this paper is to compare resulting deformation of the slab, subsidence of the subsoil, bending moments and contact stress calculated by two different software based on FEM calculations. Calculated deformation of the slab is compared with deformation measured during experiment.

Abstract: Temperature effects are significant to the sustainability of integral abutment bridges with the elimination of expansion joints. The thermally induced lateral movement of the structural components is opposed by the backfill soil supporting the components of integral abutment bridges. A 2D finite element analysis was performed on a typical integral abutment bridge using OASYS SAFE to investigate the complex interactions that exist between the pile supporting stub-type integral abutment and the backfill soil. The primary objective of this paper is to compare the effect of various soil types on the displacement of the piles when subjected to lateral loading and secondly to identify the significance of cyclic lateral load on the behaviour of the piles for various foundation soil types. The results suggest similar effect on the integral pile displacements for investigated soil types, especially for non-cyclic lateral loading.

Abstract: Seismic response of shallowly buried underground under vertical seismic excitation is studied. In order to simplify the analysis two steps are adopted in the analysis. In the first step structure is looked at as rigid body, and the dynamic response of the structure under vertical seismic excitation is obtained on the basis of soil-structure dynamic interaction analysis. In the second step at first the natural frequencies and mode shapes of the structure are obtained with consideration of the bending restraint of the side walls to roof slab, and then the dynamic response is determined by taking the dynamic response of rigid body in the first step as input, and furthermore the bending moment of roof slab is obtained. Key words: vertical seismic excitation, roof slab, soil-structure interaction, dynamic response

Abstract: In the context with the solution of interaction of foundation structures and subsoil is complexity of a static solution given mainly by selection of a computational model, effects of physical-nonlinear behaviour of such structure and co-effects of the upper structure and the foundation structure. The purpose of this paper is to compare subsidence of the foundation measured during the experiment and numerical calculations based on FEM. This paper describes how calculated deformations depend on parameters of subsoil modelled by 3D finite elements. The parametric study includes charts of the dependence of resulting deformation on the choice of boundary conditions, on the size of the modeled area represents the subsoil, on the depth of 3D subsoil model and the size of the ground area 3D subsoil model.

Abstract: This paper is aimed to analytically study the ultimate state of bridges with seismic soil-pile-structure interaction. Since the Vector Form Intrinsic Finite Element method is superior in managing highly nonlinear engineering problems even with fracture and collapse, it is used in this study to predict the failure process of bridges. During an extreme earthquake, soil may undergo plastic behavior, and piles may go through cracking, plastic hinge, even fracture. In this study, several nonlinear soil-spring models are developed to simulate the soil-structure interaction behavior under strong ground motions. Through a series of parametric studies, the failure modes are demonstrated for bridges with pile foundation. The result showed that, both soil and piles went through plastic behavior. It is suggested to analyze bridges under strong ground motions by using nonlinear soil elements for realizing the actual dynamic behavior.

Abstract: The seismic response of step-terrace frame structure is affected by the slope. Considered soil parameters of slope, the floor numbers and span numbers of layers below the scarp, 45 step-terrace frame example structures were designed, and three excitations at bedrock were selected to analyze the example structures response with dynamic time-history analysis method. The research indicates that when the other conditions are the same, the soil becomes softer, or structure's span numbers on the slope becomes larger or the slope becomes higher, the dynamic interaction between slope and step-terrace frame structure becomes more obvious. When the inputted ground motion at slope foot is adopted and the slope soil is soft, the seismic response of structure without soil-structure interaction is smaller than that of with soil-structure interaction.

Abstract: A state space method has been put forward for finding the deformations and internal forces of piles subjected to lateral loads. First of all, a pile was divided into a number of pile segments, on which the foundation reaction coefficients were viewed as a constant based on the three parameter method. Secondly, state space equations of all the pile segments were established according to Euler-Bernoulli’s beam theory and the equilibrium conditions of a pile segment. At last, a state space solution of a pile subjected to lateral loads was obtained using the boundary conditions at the top and bottom end of the pile and the continuous conditions at the interfaces between two adjacent segments. Numerical results show that the state space solution agrees well with the semi-analytical one, and all the computational formula, procedure and programming are very simple.