A note in Shallow pointed arch

Scholars have considered structural behavior of pointed arches deeper than semi-circular: they have less horizontal thrust in comparison to semi-circular arch. However, in Persian architecture, some pointed arches shallower than semi-circular have been used for centuries. Specifically, in the Safavid era, one of these pointed arches became so prevalent that its widespread use helped make it a symbol of this era. Noting that descending the crown increases horizontal thrust, why did master builders use such arches? Using a displacement-based approach, by interactive thrust line analysis, the author examines three prevalent arch forms, a Sassanid three-centered arch, a four-cantered arch documented by Jamshid Kashani and the Savafid Panj-o–haft arch to answer this query. The results demonstrate that although this geometrical change increases the horizontal thrust of arches, it also increases the seismic resistance of these arches: the most important structural issue in Iran