Ozgur, MehmetBozdogan, Kanat Burak2025-01-272025-01-2720232687-301Xhttps://doi.org/10.46464/tdad.1184558https://search.trdizin.gov.tr/tr/yayin/detay/1183718https://hdl.handle.net/20.500.12428/13445Soil-structure interaction (SSI) results in higher structural damping ratio and elongated fundamental natural period of the building. Generally, these modifications on dynamic properties of the building are regarded to be favorable for dynamic response and SSI is neglected in most of the design codes. However, extensive research points out that neglecting the role of SSI can be a misconception that lead an unsafe design by underestimating the rotational ductility demand and top displacement of the building. Therefore, it is essential to determine if SSI is expected to be significant for safe design of the buildings. In this study, the significance of SSI in design is assessed with the help of the structure to soil stiffness ratio that is considered as the most important parameter controlling the period elongation. Stiffness ratio is determined for buildings with moment-resisting frames and varying number of storeys resting on different soil conditions and a threshold of 0.1 is assumed as the critical value that yields a period elongation of 5%. It is shown that, SSI should be taken into account for buildings founded on site classes ZE, ZD and ZC and can be neglected for site classes ZB and ZA. © 2023 The Author(s).trinfo:eu-repo/semantics/openAccessPeriod elongation; Soil-structure interaction; Stiffness ratioArticle51698410.46464/tdad.11845582-s2.0-851688078981183718Q4