Principles of soil-structure interaction under seismic disturbance - Principles and inertial effects

The subject of this article is the interaction between the soil supporting the structures, the foundations and the superstructure under seismic loading: soil-structure interaction (SSI).

The stakes are high from both a technical and economic point of view. Realistic characterization of this interaction can be either beneficial, such as reducing internal stresses in the structure, or preventive, in the event of identified undesirable effects.

The advent of the "Eurocode" standards, and in particular Eurocodes 7 and 8 (EN 1997 and 1998 standards), has accelerated the widespread revision of documents relating to soil and structural foundations. In particular, the latest generation of codes for dimensioning structures in seismic zones, such as Eurocode 8, encourages the development of dimensioning based on soil-structure interaction in static and dynamic conditions.

Rather specific to the know-how of a small number of specialists who know how to deal with seismological data, soil and structural dynamics, as well as geotechnics, the concept of soil-structure interaction is spreading in engineering, but sometimes comes up against existing boundaries between disciplines.

The approach proposed in this article is to bring together the principles of ISS in order to give the engineer the key stages, as well as the successive levels of refinement he can bring to his analysis.

The basics of soil-structure interaction under earthquakes is divided into two articles, the overall aim of which is to present the specific issues involved in soil-structure interaction and the tools available to engineers for studying foundation problems.

This article reviews analysis methods, introducing rheological and numerical models. The principles of characterizing the response of structures under earthquakes using analog models and the analog representation of inertial interaction are developed, before detailing the mass effect and the radiative damping of the ground.

The other decisive component of soil-structure interaction, relating to kinematic effects, is presented in the rest of this article [ C253 ].