Optimal Parameters of Form and Structure of Rotational Symmetrical Synclastic Shells (RSS) in Nature and ArchitectureCase Study: Bird Eggshell

Natural forms and structures have always been a source of human inspiration for the creation of space. The present study focuses on one of the most important sources of inspiration from nature, namely Rotational Symmetrical Synclastic shells (RSS), and deals with the formal and structural optimality of these shells and their role in architecture. The methodology of this research is descriptive-analytical and simulation. It also uses primary sources and case studies in nature, such as bird eggs to analyse the form and structure of natural RSS shells, and to determine how to use their capacities in architecture. To this end, the article first addresses the typology of RSS shells. Then, the formal principles of RSS shells in nature are examined, which include various formal structures. Then, the typology of these shells in past and contemporary architecture is examined, including different types of arches and domes based on compressive or tensile behaviour. Another objective was to study the formal and structural optimality parameters in nature and architecture. It is very important for architects and designers in this field to have data control in order to achieve optimal and innovative forms and structures. Due to the variety of RSS shells, the focus of this research has been on spherical and parabolic examples. In the study of the "circular parabolic" shells, first, the required parameters were defined. The parametric definition of "spherical" and "circular parabolic" surfaces showed that the optimality of the shell surface can be achieved by adjusting parameters. In order to identify the optimality parameters of RSS shells in nature, bird eggs were examined as a case study. Various studies have shown that many parameters are effective in the optimal formation of bird eggs, such as: clutch size, roll factor, Hand Wing Index (HWI), degree of conical or elliptical egg elongation, and structure of the egg, among others. On the other hand, changing in numerical parameters also showed that by increasing the height of the egg, surface optimality in relation to volume can be increased. In examining such natural RSS shells, which are great examples of natural structures, we arrived at hidden rules and parameters. Some of these have been implemented in architecture, while others have not yet been considered. The ones that have generally been implemented are: achieving formal and structural optimality with maximum resistance in large openings, using the least materials and having minimum surface area, reducing resistance to lateral wind forces in minimal formal and structural contact, and having an optimal form in response to environmental and weather conditions. However, the findings show that there are other rules, which should also be considered by architects, such as design and implementation of context-sensitive in-situ shells and prefabricated shells focused on the specificities of each context, and utilizing new technologies to achieve maximum optimization of form and structure in RSS shell architecture. Thus, by examining natural RSS shells, it may be possible to achieve new and more efficient architectural ideas and design processes.