Soil-pile-structure interaction evidences from scaled 1-g model

The seismic soil-pile-structure interaction (SPSI) is a complex mechanism that is usually considered formed by the combination of kinematic and inertial interaction. Both mechanisms generate additional forces on the system related to the stiffness contrast between the soil and the foundation for the kinematic interaction and to the soil response around the foundation due to the inertial contribution of the superstructure for the so-called inertial interaction. While the mechanism of each of these contributions is clear, their combination is still under investigation due to number of parameters involved (i.e. dynamic characteristics of both system and input). An effective way to study this combination is the analysis of actual data on real structures. Due to the fact that these data are hard to find, usually the response of physical scaled models on 1-g and n-g devices are investigated. In this connection, this paper presents some results from an extensive 1-g shaking table testing activity. The scaled physical model is formed by a group of five piles embedded in a by-layer deposit of dry sands with an oscillator connected to the piles through different kind of foundation systems. More specifically, the attention is focused on both pile and structural response when the oscillator is connected to a small group of three piles by means of a stiff foundation. The analysis of the experimental data enhances the role of the resonance between the soil-structure system and the input waves in the general behavior of both structure and piles