Influence of building-site resonance and building properties on site-city interaction: A numerical investigation

Recently, the concept of ground motions within dense urban areas being significantly affected by upper building clusters has been widely accepted. However, multiple interactions between upper buildings and underlain soil layer have increased the complexity of the problem. In this study, we focused on the analysis of ground motion changes with respect to free-field motion caused by upper building clusters, and the seismic interaction between building clusters and underlain soil, named site-city interaction (SCI). Emphasis was placed on the influence of building-site resonance and building properties on SCI effects. Hence, a two-dimensional (2D) numerical finite element model coupled with a non-linear elastic-plastic soil model and a linear multiple degree-of-freedom building model was developed in the OpenSees framework. Numerical results showed that the SCI effects were strongly influenced by the building-site resonance effects and building properties. For special cases, the ground motion was reduced by more than 60% with respect to the free-field motion. Furthermore, the SCI effects decreased as the degree of soil non-linearity increased, whereas the ground motion caused by SCI effects reduced by more than 20% of the free-field motion. However, owing to the non-linear effects, several unexpected amplifications were observed at certain frequency bands. Overall, the results of this study present an insight into the relationship between building properties, buildingsite resonance effects and SCI effects, and provide a reference for further SCI analysis of real-life applications.