Abstract
The natural vibration period of a structure is an essential parameter for earthquake-resistant design, performance assessment, and structural health monitoring. However, it is challenging to quantify for existing structures and ancient construction typologies that are not properly covered by design standards. This paper investigates the natural vibration periods of historical masonry minarets through a database of 111 structures from Egypt, Turkey, Jordan, and Bosnia and Herzegovina, compiled from literature publications and local archives. The database includes minarets with different geometries, architectural styles, conservation states, ages, and dynamic information determined either from ambient vibration tests (AVTs) or finite element analyses (FEM), depending on data availability in the original sources. Empirical models are proposed to estimate the natural vibration period using simple geometric parameters: the total height $$H$$ and a representative external plan dimension $$D_{rep}$$ , defined as the main body external diameter when available, or as the reported base dimension otherwise. The equations are developed through log-log regression and explicitly include the residual dispersion in logarithmic space, allowing the uncertainty of the estimates to be quantified. To avoid calibrating the empirical formulations on potentially uncertain numerical results, only AVT-derived records are used for the proposed regression models, while FEM-only records are analyzed separately as a comparison subset. Results show that height is a relevant predictor, while combining $$H$$ with $$D_{rep}$$ significantly improves prediction accuracy. The resulting bivariate model, $$LL{\rm{ - }}BI\left( {H,{D_{rep}}} \right)$$ , provides lower dispersion and stronger statistical performance than the height-only formulation. A focused analysis of Cairo’s minarets further indicates that both slenderness and the bivariate formulation are informative within this more homogeneous subset. The proposed model provides a practical tool for preliminary period estimation and large-scale seismic risk screening of masonry minarets.