Περίληψη:
The important role of soil-pile-structure interaction on the seismic response of pile-supported
structures has been widely established by several theoretical and experimental studies. However, due
to the complex nature of the physical phenomenon, the identification of the key parameters that affect
the interaction mechanism remains a crucial task. Along these lines, the frequency content of the
seismic motion constitutes an important parameter that affects the intensity of soil-pile-structure
interaction phenomena and consequently the seismic response of pile-supported structures. In this
paper, soil-pile-structure interaction is numerically examined in the frequency domain in order to
obtain an insight on the effect of the natural frequencies of the system on pile and structural dynamic
response. Kinematic soil-pile interaction is initially investigated under harmonic excitation applied at
the base of the soil profile, emphasizing on the effect of the soil fundamental frequencies on the pile
bending moments. Within the framework of the validation of the adopted soil-pile model, additional
analyses were performed implementing pilehead loading in order to obtain pile impedance functions
and compare them to existing analytical formulas. In a second stage of analysis the coupled soil-pilestructure
system is examined, adopting single pile-supported structures with different dynamic
characteristics. Soil-pile-structure interaction effects are discussed in terms of the fundamental
frequency of the superstructure, the bending moments generated along the pile shaft and the pile head
motion. The analysis results indicate that for certain soil-pile cases, the kinematic peak pile bending
moments may occur at frequencies higher than the fundamental frequency of the soil deposit. On the
other hand, the investigation of the coupled soil-pile-superstructure system revealed that structural
oscillations transmit large bending moments on the pilehead when the modified frequency of the
structure due to SSI effects is close to the fundamental frequency of the input motion. Furthermore, the
combined effect of inertial and kinematic interaction may under certain conditions result in a
significant amplification of the pilehead horizontal motion at the fundamental frequency of the pilestructure
system.