Persian Architect's Mastery over Geometry to Build Discontinuous Double-Skin Domes in Nain Style

Since centuries ago and due to time and necessity, Iranian architectural roofs have been built in various forms and evolved in the course of time. The Iranian Architectural roofs can be divided into two general forms: flat and curved. Domes are of curved roofs among which discontinuous double-skin ones have salient features. In terms of architectural form, structural characteristics and geometric proportions, double-skin domes are among the important elements of Islamic architecture and need to be investigated extensively. Close structural analysis of double-skin domes may offer approaches to restore them more effectively. The present research aimed to show that there has been a direct relationship between form and size of the domes, and between the traditional architects’ mastery and creativity as well as techniques to build the domes. The structure of double-skin domes in Nain Style was examined as closely as possible. To do so, the primary data were collected through library sources, field studies and recordings and conducting interviews with restoration experts and architects. Then, geometric proportions and structural characteristics were modeled digitally by 3-D soft wares. Finally, the results were analyzed and compared descriptively. The main focus was on studying the architects’ mastery on geometry with respect to applying creative techniques to build double-skin domes in Nain Style. The results indicated that the material used, available sources as well as the architectural mastery and capabilities of local architects who, themselves, were inspired by architects of the past generations all have had a great impact on forming double-skin domes in Nain Style. Dome has been contrived as a response to a need for elimination of columns from nave-like spaces and to create a vast space with a dominant view. Iranian domes, being constructed over time by such materials as mud-bricks, bricks and stone, have taken various forms derived from “form geometry” as well as from architect’s abilities. Iranians used it due to its ability to cover a vast space more than any other kind of covering element. Where they made correctly, domes might endure for much longer periods of time. Being an important architectural element within the frame of Iranian architecture history, as is evidenced from sample bullae discovered at susa, domes have an unexpected rather short history in western world; as we have just found one case of double shell – discrete dome from 16th century ; and some people even believe that the dome of sant marco church in venezia (14th century) ,with its inner bricked shell and the outer wooden one, has been derived from the so-called Iranian dome of Soltaniye. Among astonishing architectural elements, domes have their own high stature and some scholars refer their invention to earlier Iranian architects. Of oldest Iranian domes mentioned in written documents one can mention Bazeye-hur (of char taghi type), Ghaleye Dokhtar in Fars,as well as Firuzabad and Niyasar fire temples of Arsacids and Sassanid periods This architectural element became in intense use in post Islamic architecture and in religious buildings in particular. One sees in available domes some similar structural technology with minor differences, corroborating our hypothesis of local architects’ creativities and affecting of structural shapes. Everyone interested in cultural affairs should try to permeate the respect for artistic monuments in the society. The mystery behind learning artistic experience, as well as protection and conservation of those pieces of art, is to know how to hear, to read and to comprehend their specific features (Brandi).