Geometric nonlinear analysis of soil-structure interaction with trusses using positional formulation

Resumo

Although in many situations it is possible to consider civil structures as supported on immovable foundations, in situations of moderate settlement it is necessary to consider the interaction between the soil and the structure, considering both flexible. Soil deformability can cause considerable changes in support reactions and stresses, which are fundamental for structural design. In turn, this change in the loads transmitted to the soil causes the deformations presented by the soil to change. Thus, this work deals with coupling a formulation for nonlinear analysis of spatial trusses with a solution to the problem of settlements in stratified soils. The truss analysis follows the positional formulation of the finite element method (FEM), as presented in Coda (2018), while the soil domain analysis is based on fundamental cases of elasticity theory, as presented in Pinto (2006), Mundim, Cruvinel and Cavalcanti (2014), and in Poulos and Davis (1980), considering the characteristics of the soil based on geotechnical field tests. The calculation of soil deformation considers both the influence of direct loads on the support considered and the indirect effects of tensions due to adjacent supports, considering the variation in tension spatially, that is, along the depth of the soil below the foundation and of the adjacent region. The computational code for dynamic analysis of three-dimensional trusses is verified using analytical and numerical examples from the literature, showing compatible results. In the context of soil mechanics, the code is also verified through examples, considering homogeneous, stratified soils with three-dimensional stress propagation. Finally, examples are studied considering the soil-structure interaction, where the degree of influence of the soil-structure interaction on the results of the requesting efforts is evaluated.