Chapter 5: Seismic analysis methods related to foundation design

Different structural concepts are necessary when designing foundations. The aim of this chapter is to provide the essential structural engineering concepts that are necessary to carry out analysis of foundations. Readers are referred to standard structural dynamic textbooks for further details: two classics are by Chopra (2013) and Housner and Jennings (1982).

For any dynamic calculation, an important aspect is the determination of the time period of the structure (or its natural frequency), in order to avoid resonance or to mitigate against resonance-induced effects. In the context of earthquake engineering, resonance is the phenomenon that occurs when the natural frequency of the applied loading comes close to the natural frequency of the structure, and the amplitude of forced vibrations of the structure is magnified. The magnification depends on the degree of energy dissipation from the system (i.e. damping).