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

Prefabrication experiments - 362 - Modern structural archetypes - 02 - Space Frame Urbanism

 

The development of three-dimensional trusses, space and trellis frames, from corresponding, dimensionally coordinated and repeatable linear components patterned to cover and limit architectural space is linked to iconic names in architecture: Fuller, Wachsmann and Le Ricolais explored the links between geometric archetypes and building structures. The three engineers/architects/industrialists/inventors are synonymous with large spanning frames articulating a symbiotic relationship between structural form and architectural space through reducing material use; maximum span with minimal weight. Founded on the principles explored earlier by Alexander Graham Bell, the triangular pyramidal truss is an inherently stable modular unit aggregated, clustered or amassed to shape lightweight frames that distribute structural constraints throughout their composing elements and reticulated network. Fuller's geodesic domes, specifically the double shell domes used a triangular pyramid, the tetrahedron, to fashion form and space. Its compositing equilateral triangles seen as a simple metric for elemental fabrication. These robust, triangulated and filigree structures were used to posit new designs for housing, factories, exhibit edifices, and most surprisingly as enclosures for futuristic cityscapes. 

Inspired by Fuller's great circles and by mentor Yona Friedman (famous for his aerial megastructure city proposals), David Georges Emmerich united reticulated structural form with his singular vision of building new cities over existing ones. Involved with groups like the Congrès Internationaux d’Architecture Moderne (CIAM) and a founding member of the Groupe d’Études d’Architecture Mobile (GEAM) in 1957, Emmerich envisioned space frame structures as an opportunity to develop mobile, flexible, adaptable and everchanging megastructures in response to the rapidly evolving modern city.  His representations of Coupoles Stéréométriques present the links with both Fuller and Friedman. The «coupoles» or domes, imagined as simple to assemble shells, would enclose multi-level neighbourhoods floating within the overarching limits of pure structural form. Patent drawings provide a clue to the simple building methods that would reform cities and buildings. In a similar way to his contemporaries who explored the potential of mass-produced components to solve housing crises and offer a way forward for stagnating city form, the structuralist vision of at once covering, limiting, controlling, relating and measuring «stéréométrie» architectural space remains a unique reverie of the post-industrial city.

Stereometric Domes and patent drawings for domes

Prefabrication experiments - 361 - Modern structural archetypes - 01 - Suspended Frames

 

Tall buildings' development was a direct result of industrialization principles applied to construction. Mechanization (elevators and machines) and mass production (replicated components) simplified the assembly of larger and taller spanning edifices and increased capacity to service these vertical communities. Skeletal frames composed of normalized and optimized steel profiles made it possible to build these structures without substantially increasing their weight to span ratios. Enlarging structural capacity through standardized components is a central theme in modern architecture inspired by manufacturing principles and leveraging them in building construction. Architects envisioned steel and glass cathedrals reaching upward and searched for ways to express weightlessness. 

 

The suspended frame, a major contribution to structural engineering, is a notable example of two specifically modernist canons related to skeletal frameworks: open planning and cantilevered floor plates. Unobstructed floors are carried from above and transmit their loads to a centralized core that braces the entire structure. Outrigger frames are a variation of suspended frames with «outrigger beams or trusses» attached to the core that support one or more floor plates. 

 

A beautiful example of the suspended frame was designed for British Petroleum in Atwerp, Belgium by Léon Stynen architect in 1963. The system is a straightforward expression of the archetype: rooftop cross beams or gallow beams shape a unidirectional hanging system supported by 2 longitudinal mega-beam trusses that transfer floor hanging loads to the central core. The spanning floor plates are stayed by tensile elements suspended from the gallow beams and determine the façade’s grid.  

 

The 11 floors float over the neighboring context and seem at first glance to be supported only by the central element; Once perceived from the rooftop, the megastructure holding up the perimeter is analogous to a masterful hand holding up a rigid marionette. The rigorous structural grid is transmitted throughout the building with the curtain wall expressing the link between structure and skin; a corporate internationalization of architecture generalized during the twentieth century. All elements of the hanging structure are manufactured parts that come together to shape a flexible and adaptable large-scale building kit. The typical floor plate also deploys the basic core and adjacent spaces pattern associated with many tall buildings.

Photo by Paul Hermans licensed Creative Commons-Share Alike 4.0 

Prefabrication experiments - 360 - Fabricating Modern Structural Form

 

Notably during industrialization with the invention of new materials, methods and building types, achieving maximum spans with minimal material informed structural theory and pedagogy. Correlating these two objectives, modern architects and engineers explored varied and variable structural systems that have become synonymous with their era. From ribbed slabs to castellated beams, reducing weight while maintaining and profiling structural integrity requires intelligent constructions, assemblies, and geometric finesse.  The geodesic domes of Buckminster Fuller, the grid shell tessellations of Pier Luigi Nervi, August Komendant's concrete space frames and Robert LeRicolais' lightweight beam experiments all materialized structural conceptualizations by decreasing material use; all shaped geometry, points, lines and their networks to respond to stresses and strains in an optimal manner. 

 

Through examining beam principles, compression, and tension in upper and inferior parts of a beam with forces neutralized closer to the center of the beam, matter is directed to eliminate waste and in response to loads, producing systems that are physical illustrations of their most favorable load transmissions. Today, generative design tools make it possible to optimize the representational and structural relationship even further between modular elements, structural form and geometry; grid shell systems combine resistant forms and shapes with lightweight struts or other modular elements that can be arranged according to underlining physical criteria and material characteristics. These structural optimizations can also lead to construction efficiencies based on similar ideals of modularization, assembling edifices from multiplied dimensionally coordinated components; An idea eloquently defined by Pier luigi Nervi's patent for structural prefabrication.  

 

Stacking boxes, aligning frames, organizing, or mapping shapes from tile-like elements all speak to the relationship between structures and reproductible components - a type of piecework quilting to achieve building form.  Further, modern structural prototypes with increasing spans defined a uniquely modern syntax linked to universal, flexible, and adaptable open spaces free from any structural obstacles.  The next ten blog posts will examine structural archetypes, the modern use of grid, modularity, geometry, and replicability to showcase innovative building systems.  Prefabrication, industrialized building systems, offsite construction and platform principles applied to architecture, all, in some way, employ similar modular schemes to propose the efficient production of edifices. 

Gatti Wool Factory ribbed isostatic slab by Pier Luigi Nervi

Prefabrication experiments - 359 - Containerization of housing

 

Residential housing design employs repetitive organisations and has been the subject of industrialized production using volumetric boxes or panelized building systems in a variety of materials. Spans are relatively small and rectangular. Apartments are often repeated from one floor plate to the next with interchangeable modular built-ins for wet spaces (kitchens, baths).  These patterns guide the housing market making it an ideal sector for normalized fabrication and process replication. A notable production analogy devised to improve efficiencies in housing uses the ISO container storage unit, a stackable block determined by intermodal transport with standardized dimensions and connections as a model for building construction.

 

Normalized containers generalized and communicated a way of shipping things across the planet. The boxes also outlined a common way of storing things, aboard a ship, in a port or in warehouses.  A similar containerization strategy is behind English company Verbus’ way to quickly put together mid-rise housing.  The basic building block, a generic module looks and works much like a shipping container that has been modified and tuned according to multi-unit residential requirements. The volume, 3,6m width x12,2 m length x2.9 m in height includes openings for a central corridor, which defines a double loaded floor plate of small studio flats. Windows and balcony elements are provided on the units’ extremities.  Service shaft holes above and below the container structure standardize duct placement to pre-set vertical mechanical distribution. 

 

More than just a container, the Verbus system has been designed with attachment points to vary massing from straight linear plans to rhythmic alternating and protruding compositions. Cladding and brickwork hangers are also incorporated for any number of wall systems to be attached to the basic steel structure. The generic floor plan presents a 12’ grid with 5 juxtaposed containers, 3 of which have the corridor scheme while the two end containers complete 2-bedroom units, without the hallway space. The steel structured volumes can be stacked up to 16 stories high and have found resonance with hotel design, a definitive outlet for a containerized design.

Verbus massing and floorplate diagrams

 

Prefabrication experiments - 358 - Sterckeman caravans and a house for everyone

For better or for worse, prefabrication often evokes the preconceptions associated with the mobile home. Objectively, the negative press, suspect construction methods and low quality materials have long been forgotten. Today’s manufactured dwellings have nothing to do with pre and post-war prefabs. The obsession with mobility, the possibility of towing one’s home and using industrialized materials and processes to offer accessible dwellings endure as the objectives of the mobile home. The Sterckeman family, based in France in the small town of Seclin near the Belgium border started producing mobile homes or «caravanes», in accordance with the optimistic leisure-based dreams post WW2. As was the case with other mobile home companies, the Sterckemans also attempted to produce inexpensive fixed housing prototypes. 

 

A long-lasting partnership with well-known French architect Paul Chemetov, who had designed commercial and industrial buildings for the family, led to the company's experiment related to one of modern architecture's central themes: A house for everyone. Charles and Ray Eames, Jean Prouvé, Frank Lloyd Wright, Alvar Aalto, Cedrick Price, and the list could go on have all taken a stab at the problem of affordable, manufactured, and well-designed single-family dwellings. The Chemetov-Sterckeman relationship spawned a house made from mass-produced components. Developed on modernist canons, the house floats on pilotis (slender posts) but is grounded by a vertical service core that leads to and serves first story living spaces. A core-house in its most canonical expression, the centralized outward radiating grid-based geometry arranges the plan, its structure and supports external appendages suspended from the steel skeleton. The house showcases its elements as a part of an industrial kit; bay windows are made from repurposed skylights and tubular railings expose the design's link to off-the-shelf zeitgeist and narrative that architects love to argue for to reduce costs. 

 

The architectural prototype is a protected heritage landmark and was extended during its service life. The Sterckeman dwelling was part of an exhibit on Chemetov's work at the Cité de l'architecture & du patrimoine in 2012, showcasing the continued interest in the modernist dream of combining manufacturability with architectural impetuses.

Sterckeman - Chemetov house and excerpt from caravan catalogue

Prefabrication experiments - 357 - Bien Zenker Automated Production of Panelized Homes

 

Offsite production of building sub-assemblies is often compared to conventional construction to state its advantages in terms of costs or scheduling. Manufacturing has an immense potential to reduce costs through process standardization and has already shown to be quicker and more efficient through overlapping on and off site tasks. One point that should be made in favour of offsite construction is that construction quality is substantially increased as most work proceeds in a controlled setting leading to the same productivity gains made by most other industrial sectors. 

 

Offsite construction is not only about building indoors, away from unpredictable weather, but the controlled environment speaks to a harmonized process tuning supply chains, with design, information management and Lean production principles. Bien Zenker, a German house kit-of-panels producer offers a successful case study of applying famous German engineering and production knowledge to house building. The company manufactures panelized modular homes with a large catalogue of customizable models. The entire process is robust and anchored in a plant that combines automation, robotics and human intervention to manufacture dimensionally regulated panels. Timber elements are cut, set in position, fixed and assembled with other building materials to produce sub-assemblies for walls, floors or roofs with a preciseness that is rarely achieved on site. Once delivered, elements are stitched using extended weatherproofing barriers and materials.

 

Along with the obvious advantages of being quicker than conventional construction, the factory-produced panels go together seamlessly and with digitally modeled precision. The factory uses a linear process where panel skeletons are made on automated tables. Framing and assembly proceeds at worker’s arm length at an ideal level for quality control before the skeletal panel moves on to subflooring, sheathing or insulation depending on its final position in the overall house's assembly diagram. The flatpack panel strategy transports the simplicity of kit building to the jobsite as all panels are sequenced and identified to dictate the construction process. With the overlapping of tasks, panels can be produced while foundations are cast on site speeding up projects’ delivery substantially and showcasing an ideal relationship between on and offsite strategies. 

Bien Zenker panelized homes

 

Prefabrication experiments - 356 - Ecocapsule mobile dwelling

The ability to situate a home in any context according to needs, employment opportunities, or migration patterns underscored the development of the mobile home in the USA, the minimum dwelling in Europe and the plug-in pod in post-war Japan and beyond. The small portable house is a recurring figure in response to crises. The tiny house movement is spawning current attempts to bridge mobility and domestic comfort. 

 

Developed in Slovakia by the Ecocapsule startup founded by Igor Zacek, Sona Pohlova & Tomas Zacek (Nice and Wise, architects) in 2015, the egg-shaped micro-dwelling can be set anywhere on its leveling supports. Completely self-sufficient, the unit is powered by solar panels covering the elliptical roof and an optional wind turbine for supplemental power. Deployed as a fixed camper, mobile office, pop-up accommodation or a research station, the off-grid microarchitecture will suit different functions and sites over its lifespan. 

 

It's not clear how many of these units have been produced and it may be archived as another marginal prefab experiment. Like many previous capsules, the 8m2 space is structured by a steel chassis covered with aerodynamic composite fiberglass skins. Appearing more like a vehicle than a building in its renderings, it federates current and postwar prefab quiddity defining buildings as products.  The ellipse’s two centers arrange the plan. An entry leading to a camper like kitchen and bathroom, including a WC shower and small sink define the first while a foldable bed, table and a small storage space envelop the second focal point. The flexible built-in furniture can transform a workspace into a sleeping space. The interior is molded into the egg-shaped form establishing a comprehensive product / human ergonomic integration. 

 

Similar in discourse to Kisho Kurokawa’s, now dismantled, Nagakin Capsule Tower from the early 1970s, some 50 years later, the Ecocapsule takes the idea one step further by including complete self-sufficiency. Suggesting an untethered lifestyle, the only element that seems to be missing from this complete dwelling pod is an integrated form of mobility and a capacity for aggregating multiple units into inhabitable clusters.

Ecocapsule set in a landscape

Prefabrication experiments - 355 - mnmMOD modular panelized construction

 

Modular volumetric construction is gaining traction throughout North America. Stacking large manufactured container-like boxes to create buildings is often idealized but remains dichotomic, opposing production and customization. Volumetric modular is controlled by transport criteria and repetition is key to achieve economies of scale. The essence of modular is often related to volumetric but the term refers more correctly to using dimensionally coordinated elements to inform building design – a module can be any standardized element that regulates a project’s dimensions. Modular panelized increases potential for design freedom using prefabricated planar components to shape walls, floors and roofs.  Panels can be designed, fabricated and even modularized for a specific design. Stressed skin timber panels have been produced for years and are an easy way to speed up construction as components are assembled in a factory setting while construction proceeds on site. 

 

Design, fabrication and construction flexibility are at the heart of the mnmMOD-insulated panel invented by Tryggvi Thorsteinsson and Erla Dögg Ingjaldsdóttir. Expanded polystyrene foam moulded over and united with a cold-formed steel stud skeletal structure shapes strong, lightweight and high thermal resistant composite wall or roof elements. Panels are defined and dimensioned according to project layouts, fabricated, flatpacked and shipped on site where they’re simply assembled to form the envelope of any low-density structure. 

 

The mnmMOD panels are the central piece of an ADU (Accessory Dwelling Unit) start-up founded by the same Icelandic designers. MnmMOD panels showcase the platform theory used for years in the automobile industry applied to building construction. The panel is the basic dimensional unit that can be arranged in different shapes and formats to achieve multiple designs and in this case by different companies.  Plùs Hùs is the rudimentary microdwelling that uses the panels for walls and roofs anchored to a concrete slab. The unit is little over 300 square feet and can be personalized from a simple shed structure to a functional living space including a small bath and kitchen. 

 

Both modular volumetric and modular panelized systems allow for the overlapping of tasks that makes offsite construction a quicker alternative to the linear process of conventional building. Working with panelized subassemblies leaves more work on the job site than volumetric, but flatpacking panels optimizes transport. Further panels can be packed in sequence to further speed up construction.

mnmMOD composite EPS-steel stud panels

 

Prefabrication experiments - 354 - Gablok building system

 

Building with blocks is equally representative of ancient and present-day construction culture and has been outlined by master-masons as well as do-it-yourselfers. Amassing units that interlock or are bound together characterizes a modular adaptability associated with bricklaying. Frank Lloyd Wright’s Textile Blocks, modern cinder blocks and even mass timber logs have been proposed to be juxtaposed, aligned, stacked, and interlaced into innumerable brickwork patterns. While most masonry systems require some form of fixing or binding agent to hold elements together, dry assembly, like tongue and groove or knob and tube strategies has been envisioned to integrate intelligible strengthening details to further streamline construction.  

 

Inventor Gabriel Lakatos of Belgium received a patent (2018) for the composite timber-insulation Gablok building system. The basic pieces combine OSB (Oriented Strand Board) perimeter panels with an insulating core to form a thick, high thermal performance block (around R-30). The external boards shape a modular timber cells. The insulating core fills and adheres to the box. The core is shaped and raised over the timber faces to form two knobs (square-based prism outcrops). The insulation is indented below the cell to create corresponding voids (square tubes or dimples). The square knob and tube indicate a type of mortise and tenon connection.  The blocks can simply be stacked with the extending mass filling the void in the same fashion that toy blocks interconnect. The modular 290mm x 290mm insulated boxes compose a stressed skin wall, a sandwich wall system, that is both strong and airtight, equivalent to a site-assembled Structural insulated Panel (SIP). Large factory produced SIPS usually require more complex transport and some type of lifting mechanism on site for the panels, which would become quite heavy at a thickness of 290mm. Gablok breaks the same wall into manageable pieces. 

 

Conventional construction techniques can be used to complete exterior and interior systems over the blocks. Along with the wall elements, the system is completed with floor joist and beam elements that interlock in the same way. Geared to self-builders, it is possible to introduce elements to integrate other building components such as wiring, ducting and plumbing. 

Gablok interlocking building elements