Soil-structure interaction effect

Numerical models for Soil-Structure Interaction effects are based on Finite Element Methods (FEM), Boundary Element Methods (BEM) or hybrid techniques. Although FEM are well estabHshed procedures, e.g., Bathe (1996) and Cook et al. (2002), they are not free of shortcomings especially when modeling of infinite domains is in order. In such cases special developments are required to satisfy the radiation condition... 

Veletsos AS, Tang Y (1990) Soil-structure interaction effects for laterally excited liquid storage tanks. Earthq Eng Struct Dyn 19 473 96... 

Soil-Structure Interaction Effects A key aspect in proper modeling of piers (whether inelastic or equivalent elastic) is... 

Kappos AJ, Sextos AG (2001) Effect of foundation type and compliance on the lateral load response of R/C bridges. J Bridg Eng ASCE 6(2) 120-130 Kappos AJ, Sextos AG (2009) Seismic assessment of bridges accounting for nonlinear material and soil response, and varying boundary conditions. In Coupled site and soil-structure interaction effects with application to seismic risk mitigation, NATO science for peace and security, series-C. Springer, Dordrecht, pp 195-208... 

Fang, H. Y. (1987), Soil-Pollutant Interaction Effects on the oil Behavior and the Stability of Foundation Structures, in Environmental Geotechnics and Problematic Soils and Rocks, A. S. Balasubramaniam, et al. eds. A. A. Balkema Publishers, pp. 155-163. 

A series of centrifuge tests was conducted at the University of Cambridge to examine soil-structure interaction and how the response changes when soil and structural parameters are altered. The effect of soil density, aspect ratio and structural stiffness on foundation settlement, rotation and horizontal sliding is presented in this chapter. 

Two dimensional finite element or axisymmetric bnilding and soil-structure interaction. Elements in the containment volume may model internal explosions and non-nniform temperature effects. 

Tests may be conducted either on the site or in a laboratory. On-site testing of equipment and components should be hmited to a few quahfication aspects since it proves expensive and often conflicts with accessibility. It represents a rehable strategy for the evaluation of real support, boundary conditions and ageing effects. On-site testing of structures is often the only means of capturing the actual properties of materials, global structural seismic behaviour and the effects of soil-structure interactions, and it should be carried out whenever feasible to provide results as a reference for similar structures. 

The natural frequencies of the interaction mode and the sloshing mode are obtained for various soil conditions and compared in Table 1. For the interaction mode, the effects of soil-structure interaction are obvious. However, the effects on the sloshing mode are not significant because the stored liquid can be treated as a very flexible system compared to the tank structure or the soil. Therefore, earthquake response of the sloshing height can be obtained with the assumption of a rigid tank on rigid base. 

As mentioned previously, the building model in Figure 8 has flexible foundation and the base excitations are different fi om those of fixed-base model. This is called the soil-structure interaction (SSI) effect. It is well recognized that two parameters govern the SSI effect ... 

Analysis of seismic response Response of buildings, structures and components should be calculated, including the effects of soil-structure interaction for the seismic input calculated in step 1. 

Recently it was shown 11,2] that e.g. the probability distribution of the mean wind velocity, the surface roughness as well os the characteristics of the structural damping significantly Influence the structural reliabllly estimates. Hence, in a further step the question should be answered how the additional effects, such as coupled modes, the properties of the structural stiffness as well as the soil-structure interaction influence these estimates. Therefore a model is suggested which explicitly considers these effects. 

Spread footings are usually suitable for sites of rock and firm soUs. The stability of these foundations under seismic loads can be evaluated using a pseudostatic bearing capacity procedure. The applied loads for this analysis can be taken directly from the results of a global dynamic response analysis of the bridge with the soil-foundation-interaction effects represented in the structural model. 

Pseudo-static soil-structure interaction methods 1. Good approximation of soil-structure interaction 2. Comparatively easy to formulate 3. Reasonable accuracy in determining structure response 4. Computationally efficient 5. Sensitivity analysis can be easily performed 1. Ignores inertial effects 2. Less precision with highly variable ground 3. Shear displacement not transmitted uniformly to shallow box stmctures Most conditions except for variable soil profile, shallow stmctures... 

The relative stiffness between soil and structure, stmcture geometry, input earthquake motions, and tunnel embedment depth are factors that contribute to the soil-stmcture interaction effect. The most important of those is the flexibility ratio (F) that refers to the shear stiffness of the soil relative to the stmcture that replaces it (Wang 1993) ... 

Fssi = factor that accounts for the effect of soil-structure interaction... 

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