Typology of the "Internal Form-Structure" Drawing upon Argan's Formal Approach (Case Study: Historical Bridge-Caravanserai in Iran)

In the process of defining the nature of architecture, three elements recur which are indispensable components of architecture: type, function, and structure.  The three can be related to the three attributes produced by Vitruvius, i.e. strength, utility, and beauty.  The findings of contemporary research on the discourse of typology indicate numerous contradictions between various definitions and concepts of type and typology as a general, plain image that represents a category of buildings.  Some definitions draw on the formal aspects, while others acknowledge the conceptual and intuitive facets of type.  To Quatremère de Quincy, model is to be copied and imitated as it originally is, while type is something from which any artist can extract their artworks that bear no resemblance to one another.  In 1960, Guilio Carlo Argan presented theoretical support for Quicychr('39')s ideas of typological and morphological memories.  To him, typology is not merely a statistical process or categorization. Rather, he relies on formal and functional aspects in believing that analysis and simplification of the physical functions of a structure and its configuration take place in a typological series. As per Arganchr('39')s definition, the term type applies to various levels including the formal composition, structure, and ornamental elements.  In his opinion, linking typology to the technical structure turns it into a rigid foundation for formal research.  Thus, the type becomes the internal structure of a form, or an element which encompasses unlimited form variations, transformation, and correction in its structure.  The internal structure of form can be displayed in a diagram of the shared structural attributes of a number of buildings extracted through a reductive process of comparison and elimination.  The main questions of the research revolve around the typology of the bridge- caravanserais (bridges with residential spaces) in Iran, and the idea of maintaining the continuity of old architectural traditions to employ them to meet the new requirements of such buildings. This was meant to lay the groundwork for the regeneration of creative works which are also favored by the society.  To this, the present study attempts to provide a proper typology for ten of the aforementioned bridge-caravanserais drawing upon the levels of typology put forth by Argan. It examines the void space in the bridge-caravanserais as the habitable space, their structural function in decreasing the pressure from the weight of vaults and decreasing the strength of bridges being discussed. Using a descriptive - analytical method, the data were collected through desk and field studies.  The typological findings introduce 4 different types of bridge - caravanserais. Being the most prevailing type, the first one includes spatial components (rooms) at the columns of the bridge, categorized in two groups based on the number of levels (one- and two-story). In the second category, the rooms are situated over the columns, in the space between the ridges of the arch in order to reduce the pressure from the weight of vaults. The third type has the rooms flanking the bridge as the entrance, establishing an architectural and structural link to the riverbanks. The fourth type is a combination of two or three of the other types.