What is a Megastructure?

The short-lived Japanese architectural movement of Metabolism is, Rem Koolhaas noted, notable for being the only architectural movement that didn’t originate in a Western country. I can’t say this is wrong, but I don’t feel it’s all that true either. Metabolism wasn’t exactly global and who’s to say local architectural movements are happening everywhere all the time? It’s just that we don’t hear about them and, if we do, it’s because they’ve been brought to our attention as a kind of uncritical de-regionalism/homogenization of everything. Metabolism was unique to 1960s Japan. We just made it part of our history, effectively neutering it until Archigram came along and did the same for us in metal.

1960

1961

1964

Other than its provenance, Metabolism was defined by two more things. One was megastructure and the other was the notion of growth and changeability. Isozaki’s huge steel spaceframe at Expo ’70 was more Metabolist because of its author than its megaframe. More Fun Palace than Metabolist, it was big structure but not Metabolist megastructure akin to tree trunks serving useful parts such as accommodation with services and a structure at the same time. As ever, the joy of megastructures was the impossibility of them ever being possible. Trees have no problem delivering nutrients to growth areas via a stabilizing structure but mammals do and buildings do. Putting everything inside an exoskeleton works for crustaceans but wouldn’t do for Metabolists as it couldn’t show the potential for growth and change. There’s also the problem of it looking too much like those conventional space-enclosing shells known as walls. The charm of Metabolism may have stemmed from the conceptual incongruity of its two defining characteristics but it also made it impossible to build anything other than representations of them. It was very 1960s in that respect. Expo ’70 is said to have been Metabolism’s swansong. That’d be about right. Ten years seems to be the best-by of any of those representations we call styles.

Although the idea of having services pass through mega structure was a stupid one, the other idea of a structure that allows for units of building volume to be added or replaced wasn’t much better despite buildings often needing to have units of building volume added or replaced. The problem here is one of redundancy. How much structure is going to be built to support and service an arbitrary amount of additional building volume? We can design in some structural redundancy for the additional dead load but we’ll also have to add a bit more if that load is going to be a live (changing) load. It’s a problem. Another conceptual niggle with the growth analogy is that with trees, the structure becomes more massive as the tree grows. This doesn’t happen with buildings (or with molluscs). Sure, Metabolist buildings could be (theoretically) extended with additional structure supporting additional modules of building volume but the building is now less like a tree and more like bamboo that propagates underground. This inconvenient absurdity is probably why in 1962 Izozaki produced another City in the Air proposal with incremental growth for both accommodation and the structure to support and sustain it. However, even if the building is extended horizontally, the vertical cores still need to be designed for an unspecified amount of additional load. City in The Air V2.0 is only slightly more realistic.

By 1969 megastructures were huge. They’ve since gone out of fashion but Paolo Soleri’s megastructure cities outlined in his book Arcology: The City in the Image of Man were truly impossible, visionary stuff. This next image helpfully includes The Empire State Building for comparison. What all this concrete did other than put a city up in the air was never clear. In retrospect, we might see it as a a “touch the ground lightly” move but this would be tempered by our knowledge of the planetary impact of so much concrete for so little purpose.

This has always been the contradiction with megastructures. They are first of all, structures designed for an arbitrary and unspecified amount of building volume to be added. Or are they? Maybe a megastructure is more about attitude than potential, and its primary function to support itself first and foremost? What we do know is that any structure that doesn’t work to capacity is a waste of materials and, perhaps sensing this contradiction, Soleri saw infrastructure such as dams as megastructure as having a satisfying amount of concrete and then proceeded to adorn it with botanical centers, greenhouses and other visionary stuff.

They were examples of hanging program onto an infrastructure for which a justification is assumed. It’s still naïve compared to BIG’s megastructure which monetizes airspace in those mega-infrastructures known as bridges. It assumes surplus structural capacity and that the details can be sorted out later.

If ostensibly practical megastructures such as dams and bridges have a habit of staying just as visionary as the purpose-unbuilt visionary ones, then we’re going to have think about what it is about megastructure proposals that makes them so appealing? Consider this next photograph. Is it a megastructure? It is big and it exists but it doesn’t have the visionary romance we associate with megastructures. The program it was designed for never eventuated but there’s nevertheless the potential for growth and change? I don’t think it matters. It’s all concrete not doing much and China has at least 300 massive structures such as this one which is the New South China Mall in Dongguan. What we see in this photograph is about 20% of it

These are big structures with potential but no purpose. Thinking just in terms of the amount of concrete that went into the building of structures like these, it’s an architect’s duty to repurpose them and extract some utility from all this concrete that’s already been manufactured and poured. The difficulty stems from the fact that these are specialized structures optimized for one purpose only.

In that way they’re a bit like any other highly specialized structure such as aircraft carriers that are excellent at providing a place for military aircraft to take off or land at sea, but not very useful for anything else. There’s not much you can do with a decommissioned aircraft carrier.

So yes, this post is just me arranging the the furniture here for a demonstration project to convert a shopping mall into housing. This will of course be proof-of-concept and it will involve various assumptions that will hopefully be realistic. I don’t have data or dimensions for New South China Mall so I will be using the mall I mentioned in the Mallville post as my demonstration megastructure. The mall is approximately 350 metres long and approximately 70 meters wide on average. China’s second aircraft carrier The Shandong is 305 meters long and 75 meters wide. (For reference, the USS George H.W. Bush is 332 m long x 42.8 m wide.)

Far from being abandoned, my demonstration mall is completed and fully-functioning neighborhood mall. From memory, about 50% of its retail space is food and beverage, approximately 25% is children’s after-school activities and the remainder is everything else. There are two basement parking levels, five levels above ground, and a rooftop garden.

The mall is unusual in having ten entry points at ground level, external access to all levels on the south-west side (1) and two levels of external gallery access and shops on the east side. (2) One corner has direct access to B1. (3) There are three IN ramps and two OUT ramps. All this permeability would improve liveability were it to actually be converted into housing, but I don’t expect it to make any difference to actually fitting the housing into it.

I used store directory boards and fire escape plans to create a working model.

This image of the B2 car park gave column positions. There was much variation for both the positions and the thickness of the columns, particularly around the atriums. Most of this was undecipherable using the positions and sizes of columns in the car park levels but occasional more detailed information was used for cross checkin . These next two images of B1 were vital for scaling. The basic column grid is 8.4 meters x 8.4 meters.

Car park beam depths ranged from 50 cm to 70cm but longer beams on large columns span the upper level spaces between atriums to produce column free circulation corridors on all upper levels. For the working model, I will assume that floor slabs and supporting beams are accommodated within a 1-metre thick “slab” and, for the time being, will assume an additional headroom of 70cm in places where there are no beams. A model of an assumed structure isn’t any more accurate despite being modeled in detail.

The mall levels around the atriums will have cantilevered beams as well as hidden transfer beams to deal with local events. Some rationalization and simplification would be necessary and, in order to continue, a regularized column grid of 8.4 m x 8.4 m was used but keeping the one change of direction. Floor levels of the actual mall varied between approx. four metres high for B2 to six metres high for B1 (because of sewage and water supply) and generally five meters high for all the other levels. I used a uniform FF height of 5.5 meters.

Despite the change of use, I will keep the elevator cores and fire escape stairs. I’m imagining a low-energy building but won’t make a decision on whether or not to keep the escalators functioning. Facades will be removed and the atriums naturally ventilated. Services and utilities will need a rethink.

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Mallville

Modest Megastructures

The building is not trying to be a mountain