Prefabrication experiments - 363 - Modern structural archetypes - 03 - Reticulated and lamella structures

Arches, vaults and domes are not ordinarily associated with industrialized construction or with modern building methods. Braced frames became the way forward for building with materials like steel and reinforced concrete replacing compressive masonry-based systems. With both steel and concrete skeletons, diagonal elements are used to buttress assemblies ensuring lateral stability with lightweight linear, compressive or tensile elements. Using intersecting patterns to configure and strengthen structural systems is not limited to frame construction but has also informed more complex geometries. Geodesic domes use a network of triangles in a similar way to organise reticulated spherical forms; triangles are arranged through lines of stress to construct robust lattices that act as structural membranes. Trusses use these diagonal, bracing principles to alleviate weight by creating a network of oblique segments to achieve structural inertia and optimize beam effect while using a small portion of the material that would be necessary for similar spanning monolithic beams. 

 

Triangulation is not limited to reticulated orthogonal frames. Interweaving elements in lamella-shell roof structures reinforce shapes in a similar way. Invented in 1908 by inventor / architect Frederich Zollinger the elemental ribbing is based on an analogy to mushroom cap structures. The gills or lamallae that grow underneath the cap are very thin and support a covering (the cap); together they form a very strong umbrella structure using minimal matter. The lamella roof uses this basic idea: a series of diagonal arches criss-crossed to reinforce and compose an overall space covering shell. A network of lamellas can be arranged in any vaulting structure, archetypical or free formed. The skin layer covering the ribs provides a diaphragm that bonds with the lamellas to form a thickness that is a fraction of the weight of a full shape. This principle was beautifully deployed by Pier Luigi Nervi in his airplane hangars and was also adopted in timber and steel warehouse structures. Similar concepts are used in reinforced concrete waffle slab construction, ribs and gills designed in varied grids give the slab structural strength and reduce its weight.  

Lamella archetype structure