Soil-Structure Interaction (SSI) have been studied the last decades, and proper analysis for the linear elastic case in frequency domain has been established successfully. However, SSI is rarely considered in the seismic design of building structures. Regardless of its importance as a significant source of flexibility and energy dissipation, buildings are analyzed using a rigid base assumption, and the design is based on a response spectrum analysis, for which not only the soil, but also time are totally ignored. In a first attempt to improve and to incentivize time domain analyzes compatible with standard finite element packages for the engineering community, the state-of-practice introduces two major simplifications to transform the frequency domain analysis into a time domain analysis: (a) it assumes the frequency at which the impedance value should be read is the flexible-base frequency, and (b) it also assumes that the foundation input motion preserves the phase of the free field motion. Upon these simplifications, the following questions may arise: How does NIST recommendations perform in overall against a full finite element model? Are the embedment effects for shallow foundation not important so that the phase angle can be neglected? What is the best dimensionless frequency to estimate the soil impedance? Is it possible to make a better estimation of the dimensionless frequency to increase the NIST accuracy? In this study, we attempt to address these questions by using an inverse problem formulation.
A frequency domain finite element solver for acoustic simulations of 3D rooms with microperforated panel absorbers
