Abstract:The seismic performance of underground structures differs from that of above-ground structures due to the confinement effect of surrounding soil. This paper compares the seismic performances of underground structures, considering soil-structure interaction (SSI), with above-ground structures, without considering soil, by means of the Pushover analysis method. Two kinds of reinforced concrete single-story structures with rectangular cross sections were chosen, including single-span and two-span. The research results showed that the seismic deformation of underground and above-ground structures is different. Under similar conditions, namely, with the same structure size and initial axial compression ratio, the elastic inter-story drift limit of underground structures was less than that of above-ground structures, and the plastic hinge for underground structures appeared earlier. The deformability of the underground single-span structure was weaker because of the shear deformation constraint of the surrounding soil. While the deformability of the central column of the underground two-span structure was nearly the same as that of the above-ground structure, the deformability of the lateral wall of the underground two-span structure was a bit weaker than that of above-ground two-span structure. In conclusion, even with the same structure size and initial axial compression ratio, the seismic performances of underground structures and above-ground structures are different. Therefore, existing research concerning above-ground structures is not applicable to underground structures.
