3rd Croatian Conference on Earthquake Engineering 3CroCEE

This paper examines the impact of what is arguably the most critical connection in a steel building: the column base connections under earthquake loads. Failure of this connection can lead to partial or even complete structural collapse. The rotational stiffness of these connections—whether they are considered fixed or pinned—significantly influences the seismic response of steel buildings. This rotational stiffness is determined by various factors, such as the configuration and type (exposed or embedded) of the connection. The study presents the results of non-linear time history analyses where the column base connection is modelled as a rotational spring. It emphasizes the differences in seismic response when different values of rotational stiffness are applied, including cases where the connection is considered completely rigid or pinned. Additionally, a sensitivity analysis is conducted for buildings of varying total heights and for asymmetric steel structures. Both local (element-level) and global (building-level) indices, such as column bending moments, the first significant eigenperiods, and the interstory drift ratio (IDR), are used to assess the impact of different stiffness values. The results indicate that modelling assumptions, such as those applied to column base connections in this study, can significantly alter seismic responses, underscoring the need for further investigation.