Deployable domes based on angulated scissors: A method of design based on geometrical construction

Deployable domes can be used as special roofs in large-span structures and can protect people from changing weather. In Colombia, and particularly in Bogotá, the weather changes several times during the day, so deployable domes can be especially useful. This paper presents a method for designing and building iris-type deployable domes based on geometrical construction that has been developed as part of a class-based research project at Universidad Nacional de Colombia and at Pontificia Universidad Javeriana. The interesting thing about this method is that is simpler than a mathematical method because is constructed using Computer Assisted Drawing (CAD) software or by using descriptive geometry; the process and the result are very precise and do not require special knowledge in engineering or in advanced math. During the research, it was necessary to fill the gaps in the information by trial-and-error tests; this led us to discover a hidden Fibonacci sequence, to find an accurate way to calculate the length of the scissors, and to successfully produce different shapes of domes. As a geometrical method, it could not only be used for the design of large span roof systems but can also be applied in product design, nanostructures research, and the design of other parts of the buildings as facades or mechanisms.