Soil structure interaction

The Seismic Safety Margins Research Program developed a computer code called SMACS (Seismic Methodology Analysis Chain with Statistics) for calculating the seismic responses of structures, systems, and components. This code links the seismic input as ensembles of acceleration time histories with the calculations of the soil-structure interactions, the responses of major structures, and the responses of subsystems. Since uses a multi-support approach to perform the time-history response calculations for piping subsystems, the correlations between component responses can be handled explicitly. SMACS is an example of the codes that are available for calculating seismic response for PSA purposes. 

Variations of structural properties, damping, soil properties, and soil-structure Interaction could shift the peak values of the floor response spectra on either side of the Indicated frequency. To account for these variations, the peaks of the spectra obtained from the analysis are widened by plus or minus 10 percent. 

U.S. Nuclear Regulatory Commission. Proceedings of the Workshop on Soil-Structure Interaction. Bethesda, Maryland, June 16-18, 1986. NUREG/CP-0054 BNL-NUREG-52011, Washington, DC, 1986. 

SASSI -- A System for Analysis of Soil-Structure Interaction. Report No. UCB/GT/81-02. Geotechnical Engineering, Dept, of Civil Engineering,... 

PRELIMINARY REACTOR BUILDING SOIL-STRUCTURE INTERACTION MODEL... 

Load measurement is important in any studies on the soil-structure interaction. Although the main technique of the load measurement is properly understood, the un-conducive environment and the long time period require for observing a foundation usually made measurement like this difficult and expensive to make. 

Ting, W.H. Chan, S.F. 1991. Soil-structure interaction and foundation. Theme lecture. Proceedings 9th Asian Regional Conference on Soil Mechanics and Foundation Engineering. Bangkok. 147-161. 

Simple formulae for the determination of equivalent springs and dampers for soil-structure interaction can be found in seismic engineering textbooks (Castellani et al., 2000 Roesset, 1980). Some examples are also included in the section on soil-structure interaction on p. 173. 

Figure 15-5. Modelling of the inertial soil-structure interaction by springs and dampers.

The space-time histories are, in general, deemed necessary (except for the use of approximate methods described later) for the evaluation of the response of plant components, for the evaluation of the nonlinear structural behaviour (rarely needed) and for certain evaluations of soil-structure interaction. They should also represent the duration of the shaking, which is frequently correlated with the length of the origin fault and with the velocity of propagation of its rupture. 

Roesset, J.M. (1980) The use of simple models in soil-structure interaction , Civil Engineering and Nuclear Power, vol. II Geotechnical Topics, ASCE. 

Kralik, J. Kralik, J. jn 2006, Probability and Sensitivity Analysis of Soil-Structure Interaction of High-Rise Buildings, SJCE Faculty of Civil Engineering SUT in Bratislava, december, vol. 2006/3, pp. 18-32. 

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. 

This chapter investigated the soil-structure interaction problem of a shallow foundation located on dry sand and subjected to seismic loading. Centrifuge tests and a detailed analysis were performed and allowed the rotation, settlement and sliding behavior of the foundation to be studied and understood. It was found that ... 

Bhattacharya S, Madabhushi SPG (2008) A critical review of the methods for pile design in seismically liquefiable soils. Bull Earthq Eng (Springer) 6 407-446 Bhattacharya S, Lombardi D, Dihoru L, Dietz M, Crewe AJ, Taylor CA (2011) Container design for soil-structure interaction studies. In Fardis MN, Rakicevic ZT (eds) Role of seismic testing facilities in performance-based earthquake engineering. Springer, Dordrecht/New York. ISBN 978-94-007-1976-7... 

Gazetas G, Mylonakis G (1998) Seismic soil-structure interaction new evidence and emerging issues. In Dakoulas P, Yegian MK, Holtz RD (eds) Geotechnical earthquake engineering and soil dynamics III, Geo-Institute ASCE conference, Seattle, vol II, pp 1119-1174 Kaynia AM, Mahzooni S (1996) Forces in pile foundations under seismic loading. J Eng Mech ASCE 122 46-53... 

Studies were conducted, and the results were documented in NUREG/CR-1161 (Reference 3) with specific recommendations for changes in seismic design requirements. In addition, a NRC/Industry workshop was held to discuss the complex and controversial subject of soil-structure interaction (SSI) analysis. The adequacy of seismic design of large, above ground, vertical, safety-related tanks was also of concern to the NRC. 

For example, the interaction between geotechnical and structural design of spread footings is too often reduced to little more than communicating an allowable bearing pressure, as if this single parameter was sufficient. Foundation types are sometimes selected without sufficient attention to the various soil-structure interaction considerations, which sometimes results in a foundation system that is unnecessarily expensive. 

Practitioners identification of the increasing importance of geotechnical LRFD methods and the faculty s underestimation of their importance ate significant findings of the surveys. LRFD methods clearly separate strength limits from serviceahilily limits. This increases the importance of imderstand-ing soil-structure interaction which will, in turn, increase the need for interaction between structural and geotechnical disciplines. 

In an introductory course on soil mechanics there is a limit to how far one can proceed. However, there are many more or less realistic problems which can be reduced to a single degree of spatial freedom onedimensional consolidation, flow of water towards a point sink or a line sink in a suitably infinite domain, stability of an infinite slope - these have already been mentioned. There are a number of examples of soil-structure interaction which can also be reduced to problems with a single degree of freedom. It is important to take whatever opportunities are provided by the skills and understanding that the students have developed to increase awareness of the interaction of soil and structural elements. It is not inevitable that the structural elements will always be significantly stitfer than the natural or man-made soils with which they interact (Muir Wood Nash 2000, Muir Wood 2004). 

Figure 7. Demonsiration of soil - structure interaction pack of butter indented using (a) stiff knife, (b) flexible knife.

Third, it is important to introduce explicit examples of soil-structure interaction wherever possible in every year of the degree programme. This will usually imply understanding of soil stiifriess and concepts of relative soil and structural stiffness which ate often overlooked or not thought of as relevant by those with an exclusively structural approach. 

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