Transient Dynamic Response of Soil-Foundation-Structure Systems Based on a Hybrid Frequency-Time Domain Procedure

This work presents a methodology to synthesize the dynamic transient response of systems comprised of a linear frame-structure interacting with a rigid foundation supported by distinct viscoelastic soil profiles. A 3D direct version of the Boundary Element Method used to synthesize frequency domain response of the soil profiles. The dynamics of the soil, the rigid foundation and the frame structure are initially determined in the frequency domain. A set of frequency response functions (FRFs) are obtained from the coupled soil-foundation-structure system. From these FRFs a set of modal quantities are extracted, leading to the reconstruction of a set or orthogonal equations of motions in the time domain. The integration of these equations of motion in time will deliver the transient response of the coupled system. The stationary response of the frame structure is obtained by means of modal analysis performed in coordinates relative to the rigid foundation displacements. The formulation makes it possible to consider an arbitrary number of degrees of freedom to describe the frame structure dynamics, improving the computational efficiency of the procedure. The excitation is applied to the frame structure. The formulation is three-dimensional, but results are presented for a specific plane. The methodology is computationally efficient. The resulting soil-foundation-structure time-domain equations of motion may be coupled with the linear of non-linear equations of motion from other systems such as rotating machines or turbines, leading, potentially, to the analysis of onshore wind turbines systems.