Influence of aboveground structure on connected underground structure seismic response within an integrated system

Abstract

Increasing numbers of integrated underground-aboveground structure systems (IUASS) are being constructed in densely populated urban areas. The complex dynamic interaction between the underground structure, its connected aboveground structure, and surrounding soil, brings challenges to the seismic design of such structure systems. This study aims to analyze the influence of an aboveground structure on a connected underground structure seismic response within an integrated system using nonlinear dynamic finite element simulations. The seismic response of an IUASS is compared with that of a single underground structure in both time and frequency domains, under the excitation of 9 seismic records and 0–10 Hz simple harmonic waves. The results reveal the sensitivity of the underground structure’s seismic response to the aboveground structure. Generally, the presence of aboveground structure can significantly increase the racking deformation and internal force of underground structure, particularly for the first underground story and for the underground spans directly below the aboveground structure. In such cases, the aboveground structure aggravates the tensile damage of first and second underground stories and overall compressive damage while alleviates the tensile damage of bottom story. However, when the input motion is dominated by high frequency content, the aboveground structure can act to reduce the underground structure seismic response.