Seismic Fragility of Substandard RC Frames with Soil-Structure Interaction Effects

Soil-structure interaction (SSI) has an essential role in the seismic risk assessment of existing structures. This aspect becomes even more critical in the case of seismically deficient structures on poor soil conditions. In this paper, the impact of SSI on the seismic fragility characteristics of a substandard reinforced concrete (RC) frame is investigated. First, an experimentally validated substandard RC frame is modelled as a case study building. The structural model is then paired with a soil model with two different homogeneous shear wave velocity profiles. A continuum finite element model approach is employed to model SSI, and the results are compared against the fixed-base (FB) model. The seismic fragility curves are generated using cloud analysis to highlight the impact of SSI on the seismic risk assessment for the considered structure and compare this with general guidance on explicit consideration of SSI.