An investigation in Geometry and Proportion in relation with Structural System in Buildings with Discontinuous Double Shell Domes in Tafresh Region

On top of indicating their significance, Safavid domed structures are valuable examples of design and construction techniques. Evolved from their Timurid precedents, they have initiated established regional styles which demand more research. Based on case studies, the present survey studies geometries, proportions and their relationship with structural systems in a number of Tafresh tombs based on library and on-site collected data using logical, geometric and software-based analyses, in order to eventually study the structure of the double-shell domes. This is done through examining the relationship between geometric and structural order of the whole building. Thus, the research questions are ‘what is the relationship between the structural order of the discontinuous double-shell domes and the overall geometry and proportions of the building’, and ‘what are the principles used in the design and construction of these domes’. The results show that their designs are based on those basic forms that implement golden proportions in different parts of the building. Also, the overall geometry of plans and the building’s hidden geometries, especially in their sections and façades, affect the structural order of their domes and create a connection between theoretical and practical geometry in such a way that the dimensions of the plan are effective in determining the span, the thickness of the drum and the thickness of the dome's base. The dome’s height is commensurate with the ceiling height of the building, with the dome height and stiffeners; height having a golden proportion.