Liquefaction-Induced Failure of Demirköprü Bridge Pile Foundation and Retaining System Following the February 6 Kahramanmaraş Earthquake Sequence

February 6, 2023, Kahramanmaraş-Türkiye earthquakes caused widely scattered damage in southeastern Türkiye. In this manuscript, liquefaction-induced failure of the Demirköprü bridge is discussed. The soil liquefaction triggering assessments and laboratory test results on surface ejecta suggested that the silty sand layer liquefied during the Pazarcık event. Back analyses of rotational failure surfaces revealed that the undrained residual strength and excess pore water pressure ratio values of the liquefied soil layer vary in the range of 17–30 kPa and 0.84 to 0.91, respectively. Comparisons revealed that the liquefaction induced instability would have been consistently predicted by available predictive models.