Morphogenesis of Kinetic Reciprocal Frames

Kinetic structures in civil engineering and architecture gained considerable more attention in the very recent years as a practical solution to face time dependant performances. Realized projects are mostly bridges, retractable roofs, while in architecture the trend follows the category of interactive architecture (IA) started in the sixties of last century from the intersection between architecture and cybernetics. Recent studies were focused on static and kinematic determinacy of Reciprocal Frames, but their potential in the field of kinetic structures is still unexplored. Reciprocal Frames (RF) were studied in the past as a practical solution to span distances with shorter elements. Leonardo da Vinci discovered interesting RF patterns and studied three dimensional arch structures for bridges. RF are generally defined as structures that forms closed circuits of forces, and where elements joins in intermediate points. In the present paper we will describe a new subset of kinetic structures based on reciprocal frames topology and pin-slot constraint, a connection where a pin is constrained to move along a slot, and to rotate around its axis. The first step in obtaining a kinetic reciprocal frame is to substitute in the intermediate connection the rotational hinges with pin-slot constraints. The second step it to determine the shape of the slot so as that the desired motion are compatible with the given constraints. The morphogenesis procedure is explained, in particular the operations performed from the imputed data, i.e. the imposed displacement of the elements and the topology of the connection between elements, to the output data, i.e. the shape of the elements.