Characterizing Dynamics of Pile-Supported Structures using System and Subsystem Identification Methods

Using a small number of modal parameters, we effectively describe the global dynamics of a centrifuge model comprising a pile foundation in improved soft ground. We applied subspace state space system identification (4SID) and transfer function methods to estimate the modal parameters from the pile bending moment data and accelerometer measurements of the soil and superstructure. Monitoring of the variations in modal parameters has been widely used to assess structural integrity and quantify damage. Our results show how the modal signatures of complex soil-pile-superstructure systems are governed by the modal properties of each subsystem and demonstrate that vibration-based methods can deliver practical SHM solutions for complex systems of this type