  Strong Vibration of buildings during seismic or wind loading may result in an
uplift or partial separation of the foundation from the underneath soil. To
date, various researches have indicated that Soil-Structure Interaction (SSI)
has many favorable features including a probable increase in natural period of
the soil-structure system and also a decrease in shear base demand in
structures. Furthermore, Rocking is one of the most important factors in
describing the rotational behavior of a structure built on a shallow foundation
especially on a soft soil which can affect the dynamic behavior of the
structure noticeably. To study the effects of rocking of shallow foundations
subjected to slow cyclic loading with consideration of soil-structure
interaction, a Finite Element Method (FEM) using ABAQUS software has been
deployed to simulate the rocking motion of shallow foundations. For a more
efficient simulation of the soil, both linear and non-linear elasto-plastic
behavior of the soil has been taken into account in the analysis using the
sub-routine coded in FORTRAN. The results notably show that allowing the
foundation to rock may result in stiffness degradation of the soil-structure
system and an increase in energy dissipation of soil-structure, especially in
high rise structures. Additionally, results describe that deploying the linear
elastic-perfect plastic approach may result in higher uplift of the foundation
in comparison to that using a non-linear elasto-plastic approach, particularly
in structures with lower heights.
