Abstract
With the advanced use of underground space, plans to fully connect underground structures and high-rise buildings constructed under a relaxation of floor space index in compliance with the City Planning Act have been adopted in large cities. Mutual effects among underground structures, connected buildings and surrounding soil during earthquakes and the effectiveness of seismically independent systems had not yet been fully explained. In this study, earthquake behaviors which are affected by the sizes of buildings and changes in ground characteristics were analyzed for their influence on surrounding soil and underground structures using 2-D dynamic analysis methods. The study found that seismic response in the basement of high buildings is inhibited as their mass and stiffness become larger and the relative displacement with the connected adjacent underground structure increases. In addition, from the assessment of propagation effects of input earthquake ground motion, it was also indicated that the relative displacement tends to be small when buildings work to prevent the propagation of seismic waves, while it becomes lager in the opposite case.
