Abstract:
In this paper, we evaluate force-displacement and moment-rotation relationships to characterize
dynamic soil stiffness and damping properties of structures subject to forced vibration loading. We first
introduce a procedure to extract the necessary data to develop such relationships from forced vibration testing
data. This procedure is then applied to data collected from forced vibration tests on a portable test structure at
two different soil sites in California. The results show that the outlined procedure is useful in identifying soilstructure interaction characteristics and is a convenient way of presenting field performance data from forced
vibration testing. For the data from the two sites collected, the derived relationships infer that rotational
stiffness is more frequency dependent than the translational stiffness. Furthermore, the results suggest that the
translational mode was more efficient in dissipating energy compared to the rotational mode.