pisa

Buildings That Lean

When we look at buildings or even at images of them, we barely register their shapes and surfaces before moving on to consider the next. Building alignment seems to only ever matter when it attracts our attention and one way it can do that is by thwarting our expectations.

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Why is Le Grande Arche not looking straight down the Champs Elysées? What’s gone wrong? Where’s it looking instead? Why are we personifying buildings? [And what’s with all the questions?] Back in 1985 reasons were indeed given for its non-alignment but they’ve become lost in the mists of time along with the purpose of Maccu Piccu and how the pyramids were constructed. There’s a chance we’d still remember if they’d been that important. It’s clearer with mosques. If we know a building is one then we know it’ll be facing Mecca even though it might not be aligned with anything else we see.

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Another way alignment makes us aware of it is when something isn’t in vertical alignment – as in leaning, tilted, skewed, listing … askew … squiffy. The dish of this next building doesn’t look like it’s facing anything in particular but, if we know what this building is and does, we will reasonably assume it’s aligned with something out there. We simply can’t see what. Awesome yet useful structures like this and those fancy solar collectors that track the sun aren’t considered architecture because their alignments are comprehended through knowledge, not conjecture.

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The Iconic Tilt

Snøhetta’s Alexandria Library is another matter. Its cylindrical volume and single inclined surface make it look as if it rotates and tilts to track the sun. This illusion is sufficient for its alignment to be iconic, and for the whole thing to be considered architecture. I’m using the word iconic only for convenience. It’s more correct to say its alignment designates – in that it’s being used to make some sort of statement, i.e. “say something”. But what?

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First of all, we notice its alignment because it looks different from that of everything else we can see. Its alignment also seems different by virtue of it being with respect to The Sun and not with respect to ephemeral things such as roads, buildings, and coastlines. This building’s alignment creates an association of place if we know that this building is in Egypt with its long history of Sun worship. By aligning itself towards The Sun, the building has the alignment of things that are not buildings – such as sunflowers, solar collectors and sun worshippers

The Iconic Skew

The lean of the Marine Traffic Control Tower for the Port of Lisbon Authority (1997, Gonçalo Byrne Architects) also satisfies all conditions for iconic alignment. 

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Its alignment looks different from that of everything else we can see and it also seems different from anything we may know of. We sense it is a controlled lean. It’s alignment has a unity with its location in that it is leaning towards the harbour we know it is there to observe. Finally, it has the alignment of something not a building in that buildings don’t generally lean forward like a person trying to get a better view of something.

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from the architects’ website

This tower is very photogenic and part of the reason we feel comfortable with its lean is because every ‘vertical’ is inclined to produce an even and meaningful skew. The structure and plan are exactly what you’d expect.

The Statement Lean

Philip Johnson and John Burgee’s twin La Peuerta Europa [a.k.a. Gate of Europe, KIA] Towers in Plaza Castilla, Madrid date from 1989. Visually, it’s unclear whether they want to be leaning or not as their shapes are telling us one thing and their patterns another.

Structurally, they’re as you’d expect, with a vertical structural core where topmost floor plate overlaps footprint. These were the world’s first inclined tall buildings, and leaning at 15°. The lean is said to have come about by the requirement to have a large setback at the front of the site in order to clear a subway interchange but, when Philip Johnson’s involved, you can never be sure.

Again the alignment looks different from that of everything else we can see, and it also seems (or at least at the time, seemed) novel and different from anything we know. This is a strong combination of factors but any association of alignment is a weak one because it’s self-contained about the thoroughfare and so could be reproduced anywhere. There’s nothing strongly binding the two buildings to this particular place. Neverthless, the building alignment is not like that of a building in that buildings don’t as a rule lean forward as if to oversee a portal. Subjective associations that are absent are just as important as the ones that are present and the result here is a pair of buildings that are alien to their surroundings.

The Not-So Meaningful Lean

It is the same with this proposal by Vasily Klyukin. It doesn’t matter what for, for the proposal’s title, In Love, says everything we need to know.

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The intention may have been to create something iconic [ugh!] but, again, there’s no notion of association that links the alignment of this building to its surroundings. It alignment still looks different however. It also seems different in that it’s (mercifully, still,) unusual for the alignment of a building to make such a facile pointOnce more, there’s no association of alignment that binds this building to this particular place. A building having this alignment could be built anywhere and to exactly the same effect. Finally though, its alignment is unlike that of a building in that buildings don’t love other buildings let alone express it by leaning against them

Like the Johnson-Burgee towers above, it’s not iconic – merely alien. The same can be said for these next three buildings, none of evoke ideas binding their alignment to where the building is.

The Enigmatic Lean

Jurgen Meyer H’s 1999 Townhall in Scharnhauser Park, Germany is inclined 5° lean to the east. (Its atrium also has a 5° lean to the north.) As is the case with many Jurgen Mayer H. buildings, nobody knows why.  

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Cantilevering as The New Leaning

Here, the building now appears to be leaning into some serious headwind as propels itself forward. From nowhere in particular.

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The Because-we-can Lean

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Me, I prefer a linear lean but this is Capital Gate in Abu Dhabi, billed by people more knowledgeable than I as the world’s furthest leaning building. It becomes difficult now to determine what’s a lean and what’s a cantilever but degrees from the verticla are its units of measurement. With this building, the floors farthest out there are occupited by a hotel Hyatt – the same people who devised the Pritzker Prize to thank architecture for increased footfall. RMJM, the Scottish architectural firm famous for its nine lives, designed Capital Gate to have a lean of 18°.

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The Capital Gate project was able to achieve its record inclination through a special engineering breakthrough that allows floor plates to be stacked vertically up to the 12th storey and staggered over each other by between 300mm to 1400mm, which allows for the tower’s dramatic lean. 

This must be that special engineering breakthrough although I’d prefer to save that word to describe momentous discoveries such as cures for cancer.

The gravitational pressure caused by the 18 degree incline is countered by the world’s first “pre-cambered core”; a technique that utilizes 15,000 cubic metres of concrete reinforced with 10,000 tons of steel with the core deliberately built slightly off centre. It straightened as the building rose …, moving into (vertical) position as the weight of the floors has been added.

But just in case,

The building has an extra-ordinary exoskeleton or “diagrid” to absorb and channel the forces created by wind and seismic pressure as well as the gradient of Capital Gate

The Unitentional Lean #1

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Most famously leaning is the Leaning Tower of Pisa, the campanile for the adjacent cathedral. We never appreciate the architect’s success at harmonizing the Gothic elements of the bell-chamber with the Romanesque style of the tower. We appreciate how its alignment looks different from what’s around it. It’s something that occurred naturally. Nobody designed it to be that way. Its alignment is free of aesthetic baggage. How refreshing is that!?  

The tower’s foundations were laid in 1173 and this is where problems began since those foundations were improper for ground that was, it turned out, softer on one side. Unsurprisingly, the name of this original architect is not known. Construction was delayed for a century or so while the Republic of Pisa was battling neighbouring city-states. When construction resumed in 1272, the new architect Giovanni di Simone built the remaining floors with one side taller than the other to produce a tower that’s somewhat banana shaped.

It wasn’t the best idea to concentrate on the visual aspects of the problem without considering the [clue!] underlying reasons for it. The additional material on the side of the lean might have pushed the tower’s centre of gravity further in the wrong direction for the tower continued to lean. Adding seven large and rather heavy bells to the bell chamber completed in 1372 can’t have helped.

Over the centuries, various attempts to correct the lean were made but it kept increasing to 5.5°. It was only in 2001 people finally understood what was going on. [ref.]

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The exact cause of the tilt was not fully understood until 2001, when a serious stabilization effort (which began in the 1990’s) was completed. It was known prior to the start of this stabilization effort that the tower had been built atop an inadequate foundation (which was only 3 meters thick); and was constructed on very soft silty soil. Had these been the only factors at work, uniform settlement of the tower could have been expected; and the city of Pisa would play host to a significantly less famous (albeit more vertical) tower. The 800 year old mystery was finally solved by John Burland, an English geotechnical engineer, who discovered that the primary cause of the tilt was a fluctuating water table which would perch higher on the tower’s north side, causing the tower’s characteristic slant to the south. [http://madridengineering.com/case-study-the-leaning-tower-of-pisa/]

As is the way with many intractable problems, an open call for solutions was held. One person suggested freezing the soil around the tower solid – an idea wacky enough to have worked if it hadn’t required the soil to be liquidified first. One child cutely suggested digging a hole on one side and letting the tower sink into it. This is basically what was done.

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Nowadays the tower’s lean is basically constant at 3.97° and future shifts in either direction can be predicted with reasonable accuracy. 

The Unintentional Lean #2

Two of the twenty or so remaining Towers of Bologna have similar problems. As was the way, 12th century engineers believed a foundation 3m thick was sufficient to support anything. The taller of the two towers in the image below is 97m Torre Asinelli and the shorter is Torre Garisenda at 48m. Both were built to about the same height but Torre Garisenda began to lean so alarmingly its height was reduced to 48m in the 14th century. Nowadays it sports an impressive 3° lean but Torre Asinelli is none too vertical either.

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What we like about the Leaning Tower of Pisa, Asinelli Tower and Garisanda Tower is that they weren’t designed to be like that. Their alignments look different and that’s it – that’s all there is. They weren’t designed to have alignments that were novel or unusual or different in any way whatsoever. Those alignments weren’t designed to celebrate Italian Mediaval history or attract tourists to Bologna. Any associations we may make were never there. Although the Bologna towers are out of vertical alignment, their alignments are still very much the alignments of buildings.

The Unintentional Lean #3

San Francisco’s Millennium Tower is 654ft (197m) tall. Since its completion in 2009 it has sunk 16 inches and now has a two inch tilt at the base and an approximately six inch tilt at the top. This works out at about 0.04° so it’s not appreciable yet and, even if it becomes appreciable, there won’t be much appreciating going on. Here’s a New York Times report of the current state of the legals. Fingers are being pointed.

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So far, the noisiest threats involve residents who stand to lose on their investment. Millennium tower still looks vertical. It’ll be some time before its lean interrupts a game of pool or otherwise inconveniences the daily lives of its occupants. Of more immediate concern ought to be soil liquification which is a term you’d prefer to not have enter your consciousness when your building is built on friction piles in an earthquake zone having a 72% likelihood of at least one earthquake of magnitude 6.7 or greater before 2043.

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The lean of Millennium Tower will be easy to check against adjacent and more resolutely vertical buildings. For reference, the (intentional) lean of this curtain wall is quite appreciable at 1°.

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The next video was taken during the 2011 Great East Japan Earthquake.

I can’t identify the building with the dark cladding but some Shiunjuku Towers such as the Mitsui Building and Tokyo City Hall leaned up to 3’3″. Over 55 office floors this represents a lean of around 0.6°, each way, repeatedly, and for about 10 minutes. We need to remember that these were self-correcting, temporary and designed-for misalignments.

millennium-tower.jpgITALY. Pisa. The Leaning Tower of Pisa. From 'Small World'. 1990.

As we’ve discovered over the centuries, buildings with unintentional leans don’t fix themselves. It’s one thing to dig a hole under a twelfth century unoccupied tower in a grassy clearing and hope for the best, and quite another to attempt something similar for a 58-storey occupied building in a crowded city.

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This post grew from a suggestion by Chuck Choi – thanks Chuck!

3 thoughts on “Buildings That Lean

  1. Megan

    The second photo of the Marine Traffic Control Tower makes, from a distance, the tower and it’s site look like a funnel ship, so I’d guess that the tower leans so it appears to “be” a smoke stack. It’s pretty convincing if I squint my eyes!

    Reply
    1. Graham McKay Post author

      Thanks for that David! It’s really interesting. I followed the link and had a look at the plan. There was obviously a reason as it can’t have been easy to make it that way. Whatever it was it must have seemed important at the time. As it’s a late Middle Ages chapel, perhaps the reason lies there? Contrived building process as a kind of penance? Or perhaps to represent devotion? Or the possession of esoteric knowledge? Hmm, that’s not too different from where we are now. Thanks again.

      Reply

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