Response of Single and Multilayered Flexible Base for Static and Earthquake Loading Under Framed RC Structure

As it is well known that, if the effect of Soil–Structure Interaction (SSI) is to be assessed, then structure must be placed on physical soil mass with actual properties to get the perfect behavior of soil and structure rather than Winkler’s Spring Model. In case of non-interaction analysis problem, the structure is to be placed on non-yielding support; hence, it is assumed that there will be zero displacement beneath the footing or displacement is considered less than the permissible limits as stated by standards. However, the actual condition is totally different and settlement due to soil properties can be seen by naked eyes. In non-interaction analysis, the footings are design based on Safe Bearing Capacity (SBC) of soil, but as per literature review and SSI analysis done in this paper, it is observed that the footing deformation is more than permissible value and stress value just below the footing is also higher than SBC. To demonstrate the actual nature of the ground response, a multi-storey frame is analyzed with four different cases. The SSI system modeling is done using finite element method ANSYS Software program. The portal frame is modeled as elastic (linear), whereas the ground is modeled as both elastic–plastic (linear elastic and non-linear). The study gives insight into the variation of deformation and stress intensities in soil mass while considering linear and non-linear behavior of ground. In the analysis of soil, the deformation in soil mass is plotted along with depth and discussed, whereas stresses are plotted along the width with a variation for different types of soil and different loadings. Thus, after complete analysis, it is observed that both the stresses and deformations are out of permissible limit after considering the actual stiffness of soil.