Khashkhāshī in the design of Iranian detached double-shell onion domes: classification and preliminary assessment of structural role

Abstract

The detached double-shell dome comprises the outer shell, inner shell, drum, and usually stiffeners. This article closely examines a kind of stiffener, called ‘khashkhāshī ,’ within two main discussions. (I) By comparing various examples, eight cases representative of all the khashkhāshī types are selected and studied morphologically to introduce a grounded definition for khashkhāshī , encompassing twelve types assorted in three distinct structural forms. (II) By implementing a base model with variations of khashkhāshī , their different structural effects on the overall structural behaviour of the dome are analyzed using linear Finite-Element modeling subject to dead and seismic loads. Although beneficial in redirecting the force flow and decreasing the stress and span increase at the expense of added weight, khashkhāshī might cause localized inefficiencies in some cases. The obtained results are solely for a better understanding of the behaviour of the khashkhāshī , and shall not be directly used for studying individual cases.