Concept for Consistent Soil–Structure Interaction Regarding Structural Analysis

Soil–structure interaction (SSI) plays a decisive role in the settlement behavior of shallow foundations, where soil stiffness, structural stiffness, and load application interact in a coupled manner. While traditional SSI concepts such as the system stiffness method provide robust results for many standard cases, they often rely on simplifications that may mask important mechanisms, particularly differential settlements and their feedback on structural forces. This paper proposes a systematic approximation strategy that bridges geotechnical settlement analysis and structural assessment. Parametric studies on frame- and wall-type buildings, combined with a detailed case study, demonstrate the influence of key factors: (i) structural stiffness representation, including staged construction and time-dependent effects such as creep and cracking; (ii) load application strategies, ranging from holistic modeling to simplified approximations; and (iii) the interaction between construction sequence and soil consolidation behavior. The results highlight that 3D structural models, or at least the participating structural part, provide the most reliable settlement predictions, and that a holistic load representation is essential to capture realistic redistribution. Simplifications remain valid for simple cases, but considering stiffness reduction due to cracking and staged construction is essential for reliable long-term assessments. The proposed concept offers a transparent path for both optimization and reliable settlement prediction, without increasing geotechnical investigation efforts.