TECHNIQUES TO CARRY WEIGHT LOADS AND RESIST AGAINST BENDING IN CONICAL SHELLS, STUDYING CASE STUDIES OF KASHAN

Little has been written about the structural behavior of conical shells, while conical shells’ construction techniques due to the high rise and small span has always required special attention throughout the history of Islamic architecture. This paper aims to examine how conical shells bear weight loads and resist against bending through a qualitative analysis. After proving that ‘rise/span’ ratio affects weight loads and bending in external shells greatly, the main question of the paper is “what construction techniques architects adopted to carry weight loads, and how these techniques differed in domes with various ‘rise/span’ ratios”. To find out about paper’s main question, architectural maps and dimensions of six cases were documented, according to which some ratios and parameters have been defined to find out their probable correlation with ‘rise/span’ ratio.
Results show that to restrain weight loads in external shell, design of stiffeners and thickness of the conical shell play a crucial role to keep structure balanced. According to the results, ‘rise/span’ ratio has a positive correlation with ‘thickness/span’, ‘height of stiffeners/span’, ‘stiffeners’ sectional area/span’ and ‘gradual decrease of thickness’. In contrast, ‘Rise/span’ ratio does not have any meaningful relationship with ‘stiffeners’ end point’ and “the number of flat plains”.