Proceedings of the First Conference Transformables 2013.In the Honor of Emilio Perez Piñero 18 th -20th September 2013, School of Architecture Seville, Spain EDITORIAL STARBOOKS. Felix Escrig and Jose Sanchez (eds.) A Novel 8R Mechanism for Reconfigurable Hypar Surface Koray Korkmaz 1 , Gözde Susam 2 , Yenal Akgün 3 1 Department of Architecture– Assoc. Prof. Dr., Izmir Institute of Technology, Izmir, Turkey, koraykorkmaz@iyte.edu.tr 2 Department of Architecture – Izmir Institute of Technology, Izmir, Turkey, gozdesusam@iyte.edu.tr 3 Department of Interior Architecture – Assist. Prof. Dr., Gediz University, Izmir, Turkey, yenal.akgun@gediz.edu.tr Summary: This paper aims to introduce a novel 8R reconfigurable mechanism which can meet different hyperboloid paraboloid surfaces. The novel design utilizes the overconstrianed Bennett linkage and the production principals of ruled surfaces. The paper begins with the brief summary on applications of hyperbolic paraboloid surface in architecture. Then the deficiencies and the shape limitations of Bennett linkage are presented. These deficiencies are aimed to be solved with a novel mechanism. Finally, proposed novel mechanism which is inspired from the basic design principles of Bennett linkage and the fundamentals of ruled surfaces is explained. Keywords: Ruled Surfaces, Hyperbolic Paraboloids, Bennett Linkage, Deployable, Reconfigurable INTRODUCTION Hyperbolic paraboloid is a ruled surface which has convex one way along and the concave along the other. We can obtain a hyperbolic paraboloid (hypar) as a ruled surface by sweeping a straight line over a straight path at one end and another non-parallel straight path. Hypars are one of the most used ruled surfaces in architecture, especially in the area of shells. Hypar surfaces in architecture distinguish themselves both with their aesthetic beauty and with their relative ease of construction. The first concrete roof of this type was built in 1922 spanning 16m with just 3 cm thickness by the famous German shell builder Franz Dischinger. This structure triggered the success story of concrete shells [1]. There are hundreds of concrete or masonry hypars which are built in the period from 1925 to 1975. Most of them come from the following nine engineers and architects: Eduardo Torroja, Félix Candela, Robert Maillart, Heinz Isler, Franz Dischinger, Ulrich Müther, Anton Tedesko and Eladio Dieste. Factories, warehouses, metro stops, grandstands, theatres, cinemas, churches, restaurants, bars and even houses used to be covered by shells. However concrete shell structures do not belong to today’s architecture. These thin shells have disappeared. First of all, they have become out of fashion and don’t make sense for long span structures. Candela was convinced that spans of more than 30 meters are not economical [1]. Moreover, they are dark structures which mean they are opaque and do not permit light to enter the space below. For natural light, openings are required but they make them even more difficult to analyze. In addition, shells are not compatible with modern building physics because the reinforced concrete does not have a good thermal insulation. Also, insulation claddings eliminate shell’s slenderness. They provide labor intensive formwork that makes shell structures expensive because especially in the developing countries labor became more and more expensive. As a summary, it is not feasible to construct concrete shells today. Today constructing hypars with steel is mainly preferred. Nonetheless, present hypar structures are still non-adaptive structures. Meanwhile, today architecture is in need of deployable structures that can offer adaptable space rather than traditional static space. Adaptable structures have been in use since humankind began to build because change has always been a part of the human life. However, the use of mechanisms scientifically in architecture does not traced back to even hundred years. In 1970, the Spanish architect Emilio Perez Piñero was the first who built deployable dome latticed structure in the modern sense. His design had led to the wide research in deployable scissor structures. The first research on deployable double curvature scissor hinge structures has been performed by Travis Langbecker. By improving Chuck Hoberman’s angulated units, he designed synclastic and anticlastic deployable structures with many angulated or polar units connected with revolute joints (Figure 1) [2]. However, numerous rigid units