Collapse mechanism of the Antakya Grand Mosque Minaret considering soil–structure interaction under the Kahramanmaraş earthquakes (Mw 7.7 and Mw 7.6)

This study presents a comprehensive forensic seismic assessment of the Antakya Grand Mosque Minaret, a historic unreinforced masonry tower that collapsed during the 2023 M w 7.7 and M w 7.6 Kahramanmaraş earthquakes. A refined macro-scale finite element model, developed based on simplified material assumptions and incorporating homogenized masonry properties within a concrete-damaged plasticity framework, was coupled with a direct-method soil–structure interaction (SSI) representation with idealized soil conditions, and its performance was compared with that of an equivalent fixed-base (FB) configuration. Modal analyses indicated that the fundamental frequencies of the FB model were approximately 26.5% higher than those of the SSI model, highlighting the increased flexibility associated with SSI. Under nonlinear time-history analyses using deconvolved and directionally rotated ground-motion records, the SSI model delayed damage initiation, altered drift evolution, and produced a collapse mechanism— characterized by upper-section failure and spire detachment— that is qualitatively consistent with post-earthquake field observations, although no direct quantitative validation is available. The results suggest that SSI can significantly influence the seismic response and failure progression of slender historic URM towers. Nevertheless, these findings should be interpreted in light of the simplifying assumptions regarding material properties, soil conditions, and model idealizations, as well as the absence of direct experimental validation and comprehensive uncertainty quantification. Consequently, this study provides qualitative insight into the influence of SSI on the seismic response and collapse behavior of slender historic URM minarets, rather than providing definitive quantitative predictions of their structural response.