Seismic response of integrated underground-aboveground structure system and simplified analysis methods for drift ratio and vertical displacement

The seismic response of underground structures within integrated underground-aboveground structure system (IUASS) is influenced by both kinematic effect from the surrounding soil and inertia effect from aboveground structures, leading to complex dynamic responses. This paper investigates the seismic response of underground structures in IUASS. Dynamic simulations are conducted using both elastic and elastoplastic constitutive models. The results show that the mean period of input motion and the fundamental period of the free field significantly influence the drift ratio of the underground structure, while the force at the base of the aboveground structure is also strongly correlated with the drift ratio of the underground structure. The vertical displacement of the underground structure is strongly affected by the weight of the IUASS and excess pore pressure generated in the soil. Simplified analysis methods for predicting drift ratio and vertical displacement are subsequently proposed taking these factors into consideration. The proposed methods exhibit excellent agreement with dynamic analysis results across a wide range of input motion and structure conditions, providing important tools for seismic design of IUASS.