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2008年11月22日 (土)

Bamboo scaffolding(竹足場)--香港の建築

   Nv22003_1280Nv22001_1280

写真(クリックすると拡大します)は、最近何度か登場のNorman Foster設計の香港上海銀行の建設時の現場写真です。上の2頁といちばん下の2頁ともに「Watermark Publications Limited発行(1989)のNorman Foster Buildings and Projects Volume3よりコピーさせて頂きました。」

建物外壁に、見事なまでに組まれた竹足場に驚かされます。しかしこと足場に関しては、23年ほど前に撮られたこの写真も、現在も変わっていないのです。
今回、香港に行って、高層、低層どこの建築現場も足場は竹足場でした。
 現在、日本ではほとんどの建築現場で鋼管足場が使用され、以前住宅などに使われていた丸太足場もほとんど見られなくなりました。
しかし香港では、どこを探しても鋼管足場を見つける事は難しいでしょう。
香港で竹足場が使われるのは、鋼管よりはるかに安価で、入手も簡単、軽量で運搬と取扱いが楽というのが理由のようです。市内で荷台に竹を満載したトラックを何台も見かけました。
この竹足場、誰でも組み立てと良いわけで無く、足場組み立ての技能講習を1年間ほど受けてから、実務につくと聞きました。日本の足場組み立てはとび職の仕事ですが、香港でも足場専門職の仕事のようです。
それにしても、鋼管足場に慣れている者にとっては、この竹足場はなんとも頼りなく、これで大丈夫だろうかというのが実感でした。僕は高所は苦手ではありませんが、ひもやゴムバンドで結ばれただけの、竹足場に登るのは遠慮したいというのが本心です。

Dscn3452_320写真左、志木ニュータウンの大規模補修工事での鋼管足場)
(写真中上、訪れたレパルスベイの海岸線の高層建築に、芸術的とも思える竹足場が組まれていた)
(写真中中、Topの写真と同じ香港上海銀行建設時の外壁廻りの竹足場
ークリックすると拡大します
(写真中下、同じく内部吹き抜け部分の竹足場
ークリックすると拡大します
Dscn3315_320

Nv22002_1280 Nv22004_1280

p.178

The new Bank building was conceived as clusters of layered space,

suspended bridge-like from vertical masts with service ‘cores’on the

outboard edges. These cores were built off-site in a factory by a labour

force who were not normally associated with the construction industry.

They were then shipped to the site and clipped on to the building as sealed modules, already fitted out down to the last detail of soap dispensers and taps.

Quality had been controlled in factory conditions and, by being able to

work simultaneously on and off site, the overall time-scale for the project was dramatically reduced.”

Norman Foster, Process Architecture, March 1986

The east elevation with its deep cutbacks revealing the sequence of module/stair/stair/module ‘towers’ each flanked by their own service risers. Like the modules, these risers were prefabricated in Japan and installed semi-complete units in three-storey high frames.

p.179

“To explain how an undertaking of such magnitude could be achieved within so short a time span is clearly beyond the scope of this article but four principles can be identified as fundamental to that achievement. First, the site would be more an assembly point than a building site in the traditional sense. Second, the building would be conceived and produced as prefabricated elements, manufactured around the world and then shipped or air-freighted to the assembly point.

Third, if industries outside the traditional sphere of the construction industry could offer a better performance then we would attempt to harness their skills and energies. Finally, we would actively collaborate with industry, using mock-ups and testing prototypes to anticipate, as for as possible, the eventual realities on site”

Norman Foster, Process Architecture, March 1986

The atrium under construction. This view, looking west, shows the three-storey high crossbracing in position, with the link bridges and support structure for the lift shafts beyond.

p.180

Bamboo groves are common all over Asia, with certain species growing up to 20 metres in height. Properly maintained and soaked regularly to stop them drying out, the cut poles can last for many years.

Bamboo works in tension just as effectively as in compression, so hanging or cantilevered structures can be erected with ease. Here, framing is supplied to the steelwork to provide access for the final application of corrosion and fire protection.

Traditional raffia ties may have given way to nylon straps, but in all other respects the techniques of bamboo scaffolding have not changed for hundreds of years.

It is a craft based on experience, handed down from generation to generation in close-knit family businesses.

The flexibility of bamboo allowed localised structures to be erected almost anywhere, cantilevering from the exterior of the building by up to two metres.

“I think the contrast of technology is interesting. The bamboo scaffolding for example: I don’t think it would be possible to realise this building without that indigenous bamboo scaffolding|-which erupts everywhere-any more than it would without the cranes by which it erects itself.”

Norman Foster, lecture to Sainsbury’s Executive Club, March 1984

.181

Tied securely to the building over its height, it is not uncommon, in Hong Kong, to see bamboo providing continuous scaffolding over 40 or 50 storeys.

The special rigs used to install the cladding panels could not extend to the highest extremities of the building, so bamboo had to be used instead. Shown here is the top of the east-side mast and stair tower at level 41

The final coat of paint was applied to the jib of the maintenance cranes, at the top of the building, on location. A freestanding bamboo structure was raised over 10metres from the open terrace below to provide access.

A temporary steel ‘floor’ was installed at level 11over the central atrium to provide a work platform during installation of the bank of mirrors that form the inner ‘half’ of the sun scoop. It also supported this impressive bamboo structure-which was only in place for a few weeks-used to fix the ceiling panels and beam casings that line the atrium’s soffit.

“The scaffolding is traditional bamboo which is more efficient than any more recent scaffolding; it withstands hurricanes, it goes up faster and

more cheaply. It is one of the few true vernaculars in Hong Kong.”

Norman Foster, lecture at Centre Pompidou, February 1981

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コメント

Hi, I'm doing some research on the bamboo scaffolding used for the HSBC main building and your posting has been very helpful. But I was wondering if you have all the English explanations? Some were cut off in your scans and I would really like to read them. I couldn't buy this book because it is out of print. Could you please help me? Thank you.

Phoebe Hoo

投稿: Phoebe | 2010年9月 7日 (火) 10時36分

>Dear Phoebe,
Thank you for your comment to my blog.
There are only 4 pages of description about bamboo scaffolding in the book "Norman Foster: Buildings and Projects Volume 3".
Those pages have been scanned and seen in my blog.
But as some explanations were cut off in my scans, I have added all the explanations in my blog.
I am glad if this is helpfull for you.

投稿: Souroku | 2010年9月 8日 (水) 22時54分

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