Lifetime service of Reinforced Concrete (RC) structures is of major interest. It depends on the action of the superstructure and the response of soil contact at the same time. Therefore, it is necessary to consider the soil-structure interaction in the safety analysis of the RC structures to ensure reliable and economical design. In this paper, a finite element model of soil-structure interaction is developed. This model addresses the effect of long-term soil deformations on the structural safety of RC structures. It is also applied to real RC structures where soil-structure interaction is considered in the function of time. The modeling of the mechanical analysis of the soil-structure system is implemented as a one-dimensional model of a spring element to simulate a real case of RC continuous beams. The finite element method is used in this model to address the nonlinear time behavior of the soil and to calculate the consolidation settlement at the support-sections and the bending moment of RC structures girders. Numerical simulation tests with different loading services were performed on three types of soft soils with several compressibility parameters. This is done for homogeneous and heterogeneous soils. The finite element model of soil-structure interaction provides a practical approach to show and to quantify; (1) the importance of the variability of the compressibility parameters, and (2) the heterogeneity soil behavior in the safety RC structures assessment. It also shows a significant impact of soil-structure interaction, especially with nonlinear soil behavior versus the time on the design rules of redundant RC structures.

Dans la conception courante des structures en béton armé, le comportement non linéaire du sol peut conduire soit à un sur-dimensionnement couteux, ou soit à une sous-estimation de la fiabilité, qui dépend dans la majorité des cas, de l’interaction entre le sol et la structure. A cet effet, il est indispensable de tenir compte de la variabilité des propriétés du sol qui peuvent largement influer sur le comportement des structures en béton armé vis-à-vis de l’état limite de portance. Dans cet article, on a développé une approche mécano-fiabiliste pour étudier l’effet de l’interaction sol-structure. La modélisation numérique de l'interaction sol-structure est mise en œuvre par un modèle mécanique de poutre en béton armé basé sur des appuis élastiques non linéaires. Les résultats obtenus mettent en évidence l'effet de l’interaction solstructure, et l'évolution de la probabilité de défaillance est liée d'une façon importante au non linéarités du comportement du sol.