Seismic interaction between liquefiable soil and typical RC frame clusters under code-specified seismic loadings

Seismic structure-soil-structure interaction (SSSI) has attracted considerable attention due to its vital role in the development of seismic design methods that consider the influence of adjacent buildings. However, existing SSSI studies lack consideration of soil liquefaction, failing to provide effective guidance for the design and assessment of building clusters on liquefiable soil. Based on a nonlinear finite element method validated against a shaking table test for SSSI, this study investigates the SSSI in clusters of typical low-rise, multi-story, and high-rise reinforced concrete (RC) frames built on liquefiable sand soil under code-specified earthquakes. The effects of SSSI on the maximum story drift and base shear response, and post-earthquake tilt degrees of RC frames are investigated in the context of considering the uncertainties of both RC frames and earthquake loadings. Results indicate that SSSI generally reduces maximum story drifts but increases maximum base shears in RC frames on liquefiable soil, with these effects intensifying in looser soils and under higher seismic intensities. Moreover, SSSI markedly amplifies post-earthquake tilt degrees of edge structures within a cluster. Soil liquefaction significantly increases the post-earthquake tilt degrees of edge structures within structure clusters on loose sand soil, with the maximum tilt increase exceeding tenfold under the maximum considered earthquake. Neglecting soil liquefaction generally leads to an underestimation of the maximum base shear for RC frames considering SSSI. The adverse effects of SSSI and soil liquefaction on the structure clusters built on saturated loose or medium sand soils can be mitigated or eliminated by increasing the anti-overturning abilities of their edge structures and the design seismic forces of all structures.