The suggestion of soil stiffness relationship under foundation to consider soil-structure interaction

The soil-structure interaction is one of the most important challenges in structural design that can significantly change the seismic response of structures. . During an earthquake, the behavior of the soil under the structure plays an important role in the response of the structure and affects the dynamic characteristics of the structure. Therefore, there is a need for more accurate modeling of the soil environment in special structures. In engineering applications, the soil is often not modeled and its important effects are neglected, due to the unlimited nature of the soil environment and its modeling is more complicated than the structure modeling. There are different methods for modeling the soil-structure interaction phenomenon. One of the most popular methods is the method of beam on the elastic foundation. This method is based on the Winkler model, which is widely used in the design codes, but does not accurately show the changes in soil stiffness along the length of the foundation. Therefore, in the present article, the reaction of the soil under the foundation is investigated, and finally, a suitable and simplified model is presented for modeling the soil-structure interaction in engineering applications.To achieve this goal, several structures were modeled in 3D in the OpenSees environment. Then, the output of the reaction of the soil environment and the foundation of the structure has been used to estimate the hardness of the soil environment and foundation and extract simplified engineering relations