Requirements for the reliability and cost-effectiveness of rational foundation structures determine the performance of calculations taking into account the interaction of the loadbearing structures of the building with the soil base. Computer modeling makes it possible to perform such calculations and obtain the stress-strain state of the structures of the building and the soil base.
 Numerical modeling of the interaction of a building with a soil massif makes it possible to study the influence of all components of the system "soil base - foundation - building". At the same time, during numerical modeling it is possible to consider different options for the location of elements in the plan, different geometric dimensions of the elements and their properties. The results of the interaction calculations of the building with the soil base make it possible to choose the best option for foundation structures, which is cost-effective and ensures reliable operation of the building.
 In this study, the search for rational parameters of the foundation structures of the building was performed by numerical modeling of the joint work of the elements of the system "soil base - foundation - building". The study was performed on the example of a 16-storey frame building.
 A study of the influence of the parameters of the pile foundation on the stress-strain state of the foundation structures and bearing elements of the frame of the building:
 -The influence of the piles location in the plan is considered. The process of redistribution of forces in piles depending on the amount and location within the contour of the building is investigated. Deformation assessment is performed.
 -The optimal pile length has been searched. The relationship between the length of piles and deformations, their load-bearing capacity and quantity has been studied. The distribution of piles according to the coefficient of use of their bearing capacity has been obtained.
 -A study of the influence of the stiffness of the foundation pile cap on the redistribution of stresses and strains in the structures of the building. The relationship between the thickness of the pile cap and the percentage of reinforcement elements of the frame of the building has been obtained.
 It is confirmed by the results of the research that the use of numerical modeling of the interaction of the pile foundation with the soil base allows to obtain a quantitative assessment of the stress-strain state. It becomes possible to search for rational parameters at the design stage of foundation structures.