Seismic site-city interaction analysis of super-tall buildings surrounding an underground station: a case study in Hong Kong

Understanding site-city interaction (SCI) is important for sustainable urban development in seismic regions. Due to vertical expansion of cities, super-tall buildings with deep foundations and large underground chambers are often simultaneously present. However, the role of these structures and their layouts in SCI have not been considered before. This study quantifies the effects of SCI at a congested transport hub in Hong Kong, utilizing 3D numerical modeling. At the site, 16 high-rise buildings surround a center plaza with a large metro station underground. This research demonstrates that the building layout, building inertia, and interaction between underground structures through the soil govern SCI at the site, causing ground motion perturbations and wave trapping between buildings. The presence of buildings causes up to 150-200% amplification in the short-period acceleration spectra and 150% PGA amplifications in the center plaza. Notable SCI effects on structures only appear as excess maximum story accelerations, in the order of 1-2 m/s(2), and increased destructive kinetic energy. Amid and around the high-rise buildings, SCI effects may significantly increase seismic demand on short structures. Finally, increasing the seismic demand for the design of super-tall and low-rise buildings is recommended to account for the SCI effects.

Automated summary

Understanding site-city interaction (SCI) is crucial for sustainable urban development in seismic regions. This study quantifies the effects of SCI at a congested transport hub in Hong Kong, demonstrating that building layout, inertia, and interaction between underground structures through the soil govern SCI, causing ground motion perturbations and wave trapping between buildings. Notable effects include amplification of short-period acceleration spectra and PGA in the center plaza, excess maximum story accelerations, and increased destructive kinetic energy. SCI effects may significantly increase seismic demand on short structures, requiring an adjustment in the seismic design of super-tall and low-rise buildings.