ABSTRACT
The idea of r eciprocal structures is known fro m the Middle Ages from sketches of Villard de Honnecourt, Leonardo da Vinci and Sebastiano Seglio (Popovic-Larsen 2008, Roelofs 2008). Reciprocal structures, call ed also nexorades, ar e str uctures const ructed fro m stiff element s, which lengths ar e shorter than a distan ce between fulcra of the structure. Each element is supported with the previous one and supports the next elem ent with itself. Elemen ts are supported directly one with the seco nd or in this way that fronts of second-rate elements are att ached to side surfaces of superior elements. The basic self-supporti ng reciprocal sy stems may be build from three, f our or more elements (Fig. 1). For the reason that in four-element systems, beams are perpendicular one to another, t hey are most useful for designi ng coverings of typical buildings. Elementary four-element reciprocal sy stems may be linked into com pound arrangements in one of ways shown below (Fig. 2). In this article, the attention is attracted only on them.
