Prefabrication experiments - 346 - Concrete - timber composites

Ecological imperatives are challenging the building industry's habits. Timber platform frame for houses, steel for tall buildings, reinforced concrete for fireproofed multi-unit dwellings were the accepted methods of construction since these materials and systems were normalized at the beginning of the twentieth century. Recognized as both durable and regulated, steel and reinforced concrete were generalized while timber’s use was relegated to lightweight stick building or specialized laminations for large spanning roofs for arenas or stadiums. The last few decades have changed these entrenched perceptions of steel and concrete with the rediscovery of mass timber systems specifically with CLT technology (Cross laminated timber). Timber’s low carbon footprint when compared to the high-embodied energy of steel and concrete has opened a window of opportunity for its use in any building type. Tall timber building research is profiting from both industry and policy agendas. While this seems to promulgate the same type of material silos that have hindered true innovation within the construction industry, some are looking toward hybrid systems that unite material properties to elevate quality while mitigating challenges. 

 

A western Canada based architectural firm recently proposed a hybrid solution for an «Office building of the future». The CEI architects design of a 40-floor structure combines the advantages of CLT with those of reinforced concrete. A central concrete core braces the tall structure, and a timber / concrete composite is used for floor slabs. Taking advantage of concrete’s compression strength and wood’s tensile strength floor slabs use these characteristics to optimize beam effect (concrete above neutral axis; timber below neutral axis) for spans without significantly increasing weight or sag as would be the case with concrete or timber alone. Mayr Melnhof Holz is a European company based in Austria that has brought this type of composite to market. XC is their prefabricated concrete-timber laminated slab offered in multiple modular sizes. The combination of timber and concrete increases fire protection and offers the advantage of increasing mass to simplify foundations specifically in comparison to all-timber buildings which often require tensile anchors to compensate for their relative low mass. 

prefabricated concrete / CLT slabs

Prefabrication experiments - 345 - Pluralist Tower

 

Prefabrication, mass production and industrialized building systems cultivated the potential of a new architectural language; the repetition of components, compositions or elements over a standardized grid became iconic of modernism and its modularity. One step further, these same concepts underwrote the international style that led to the erection of similar looking buildings in every city. A globalized representation of capitalism, the curtain wall tower manifested newness based on architectural and industrial integration. Many reacted to this sameness, most strongly, in reaction to how people could live in vertical towers devoid of individuality. An enduring approach created from this reaction is the open building theory founded on John Habraken's theories of a more authentic relationship to building which inscribed the duality of collective and personal elements as two necessary systems of housing blocks. Supports (collective) and infill (individual) founded many experiments where edifices no longer reflected a generic sameness but argued for individual expression outlined by a shared framework.

 

A fascinating tower project demonstrating this type of response is Gaetano Pesce's Pluralistic tower designed for Sao Paolo, Brazil in the late 1980s. Pesce envisioned the tower as «superimposed territories (platforms) equipped with the necessary services that may be bought by different owners who, with the help of other architects decide how to design the outer “skin” and the internal arrangement of every floor, with the result that a highly innovative building is created». In appearance, a complete rebuttal of modernist values, the tower expresses the distinctiveness of its inhabitants through systemic variability. It is based on a collective structure, a tall megastructure of floorplates, onto which individuals could dictate what their part of the tower would look like; a vertical urban plan with a programmed constructive freedom. A powerful manifesto, the un-built tower underscored a willingness to combine industrial potentials with design freedom. This pluralist concept while in line with Pesce's vision of distinctiveness in architecture also continues to display the difficult relationship architects entertain with mass housing: a continuous alternation between determined or undetermined arrangements. It remains to be seen how current housing needs will swing the architectural pendulum.

Pluralist Tower model

Prefabrication experiments - 344 - A universal modular building block

The ISO shipping container revolutionized the global economy. International logistics were standardized and regulated based on the idea of a normalized packaging and storing device. The universal box's dimensions along with its stackability were proposed for controlling multimodal cargoes. Organizing disparate variables from a centralized normalized unit has unquestionably contributed to  «platform thinking» as it pertains to  applying a shared model to complex supply chains. The container along with the juxtaposing, stacking clamps and simple assembly details has also inspired many to imagine the same type of assembly approach in architecture and construction. 

 

Companies like Sekisui in Japan, 369 pattern buildings - a more recent exploration on the topic - and perhaps most iconically, Z Modular, an American modular builder has proposed a chassis or rectangular prism with a structural steel skeleton that can be amassed, piled, aligned to produce an open building system. Framed by transport dimensions, the box could be used across multiple building types with medium spans. 

 

The modular universal connector invented by Julian Bowron and brought to market by Z Modular, fixes different corner elements in x,y,z directions to combine posts or beams to stack and clamp individual modules together. The patented modular box applies flexible planning principles to modular construction allowing interiors to be arranged similarly to those of conventional building systems. It is basically a post and beam structure with floors composed of steel decking and girders. Stacked and aligned units create spaces and perimeter faces that are free from structural constraints and in terms of spans are akin to lightweight timber or flat slab construction. Elevations can also be planned and composed with more freedom. The box’s universality makes it possible to oversee and propose common standards for the modular industry in a similar way to what was done in the structural steel industry or even in the concrete industry allowing varied producers to commercialize the same universal building block.   The Z Modular box also indirectly relates to the idea of Platform DfMA which evokes the platform principle applied to architecture through producing multiple designs based on the same kit-of-parts. 

The modular connector by Julian Bowron and Z Modular