Global stability analysis and soil-structure interaction. Application to EPR

During the design process of a building, several aspects have to be taken into consideration: static and variable loads, environmental conditions, accidental situations and the evolution of these along the time. An aspect that often is underestimated is the relation between the structure and the ground beneath it, the so-called soil-structure interaction (SSI). The objective of this study is to understand the theory behind the problem and find a methodology to simulate it numerically on a finite element software in order to evaluate the sliding and the uplift of a structure. The core of the study is the modelling of the interface between the soil and the structure. In computational mechanics, this is realized by means of a particular family of finite elements called contact elements. They allow transferring loads, heath or electricity between two bodies that come into contact. Then, the evaluation of the before mentioned quantities has to be done along the time. This means the use of transient dynamic analysis in order to obtain a complete displacements history of the body. All the models and analysis will be realized with ANSYS, a powerful finite element software capable to manage both contact element and transient analysis. Then, the results so obtained, will be compared with those evaluated with the Newmark-Elms methodology, a simplified numerical procedure used to calculate the displacement history of punctual mass on an infinitive rigid ground.