柳葉橋，揚州，中國

建筑設(shè)計/工程設(shè)計：馬克·曼朗Architect/Engineer:Marc Mimram

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柳葉橋，揚州，中國

Liu Ye Footbridge,Yangzhou,China,2010

建筑設(shè)計/工程設(shè)計：馬克·曼朗Architect/Engineer:Marc Mimram

這座步行橋連接了不同時期發(fā)展起來的城市兩岸：東岸是歷史古城，西岸則是新城區(qū)。它同時提供了一處與大地脫離的觀景點，讓人們在運河中央觀賞這座城市所在的廣闊平原，這里密布的運河網(wǎng)絡(luò)曾是一望無際的水稻田。

我們將步行橋的中部拓寬，以創(chuàng)造一個公共空間。結(jié)構(gòu)張開的側(cè)腹正好保護(hù)行人的安全。

設(shè)計也體現(xiàn)了結(jié)構(gòu)的錨固感。步行橋從地面升起，兩端固定以保證平衡，而支撐橋梁的大型基礎(chǔ)則深埋在土中，不會讓人看到。

因此設(shè)計可以看作是三段式的：首先是一段由坡道和樓梯組成的人行道，將行人抬升到高處；其次是橋中部的空間，面向自然和城市景觀敞開；還有兩個錨固基礎(chǔ)，作為建筑的地樁。這3個元素也體現(xiàn)在步行橋的靜力設(shè)計中，它的端頭固定點得到凸顯，而它的質(zhì)量經(jīng)過轉(zhuǎn)移，似乎不再位于兩個鉸接點之間的結(jié)構(gòu)中心。

揚州是一座重要的工業(yè)城市，擁有中國最大、最現(xiàn)代化的海軍造船廠之一。為了呼應(yīng)這一產(chǎn)業(yè)，揚州步行橋的設(shè)計就像是兩片鋼板，共同組成一道變截面的箱型梁，看起來扭曲、锃亮而纖細(xì)。

步行橋的幾何形狀借鑒了造船工業(yè)中的先進(jìn)金屬加工技術(shù)，設(shè)計得像是一片扭轉(zhuǎn)的薄鋼板，其截面變化順應(yīng)了拱結(jié)構(gòu)的壓力傳遞路徑。橋的兩端固定，內(nèi)凹的部分則更加纖薄。結(jié)構(gòu)的適宜度體現(xiàn)在受力路徑的可視性、以及在這片平面和立面不斷變化的鋼板上走過運河的樂趣之中。

該項目及其結(jié)構(gòu)所采用的材料和建造方式都與當(dāng)?shù)卦齑瑯I(yè)的專業(yè)技術(shù)有關(guān)。步行橋的獨特形式建立在當(dāng)今中國依然使用的金屬加工工藝之上。當(dāng)你漫步走過這座橋，就會驚嘆于這項工程中將結(jié)構(gòu)簡化為一塊薄鋼板的強大能力。

這項設(shè)計體現(xiàn)了材料與形式的關(guān)聯(lián)，以及常規(guī)靜態(tài)受力與特殊建造方式的關(guān)系。建筑中使用了造船業(yè)常規(guī)的金屬加工工藝，以此來體現(xiàn)結(jié)構(gòu)上不同受力的分布。金屬加工的古老技術(shù)與當(dāng)代中國的知識體系融為一體。

在這座步行橋中，結(jié)構(gòu)受力完全展現(xiàn)在它的物理結(jié)構(gòu)中。立面的舒展曲線與步行道的曲線相協(xié)調(diào)，橋的中部變寬，形成一片公共空間。

步行橋在形式蘊含的力量中體現(xiàn)了結(jié)構(gòu)的邏輯，其形式的體量變化表達(dá)了一種符合靜力設(shè)計要求的結(jié)構(gòu)形式。

荷葉的材料經(jīng)濟(jì)性一直啟發(fā)著植物學(xué)家和結(jié)構(gòu)工程師。這一座形狀極為精確的橫向箱型梁所追求的恰恰就是這種經(jīng)濟(jì)性。它擁有變化的截面，而且金屬材料的加工與受力邏輯緊密相關(guān)。

揚州人將這座步行橋命名為“柳葉橋”，意思是柳樹的葉子，這種樹在揚州的運河邊十分常見。這個名字表達(dá)了對這一采用精致加工技藝的設(shè)計邏輯的敬意。這個通俗的名字也意味著，這座橋已經(jīng)內(nèi)化于揚州的物質(zhì)景觀和社會文化之中。（黃華青 譯）

1　實景/Bridge view

2　概念草圖/Concept sketch

3　模型/Model

項目信息/Credits and Data

客戶/Client:揚州市政府/Yangzhou City

建筑設(shè)計/Architects:Marc Mimram,Architecte DPLG

助理建筑師/Assistant Architect:Aldo Turchetti

結(jié)構(gòu)設(shè)計/Structure:Marc Mimram Ingenierie S.A.

助理工程師/Assistant Engineers:Razvan Ionica,Laurent Becker

完工時間/Completion:2010.04

數(shù)據(jù)/Data:長/Length:66.23m,寬/Width:3.00～5.70m; 鋼材/Steel:50t

造價/Cost:€900,000

攝影/Photos:Agence Mimram Paris

The footbridge creates a link between two urbanized banks of the city that have been developed at different periods; on the east bank,a historic sector of the city and on the west,new urban development.It also creates a place of observation,disconnected from the ground,at the canal’s center to offer a view of the very flat horizon in which this city,composed of canals that were once rice fields,is located.

The footbridge has been widened in its center to create a public space.Pedestrians are protected by the structural flanks of the construction.

The design also marks the anchorage of the structure by extracting the footbridge from the ground,ensuring equilibrium by means of end fixings,while the large foundations that support the bridge in the subsoil are blocked from view.

The design is therefore three-fold:it proposes a promenade via a system of ramps and stairs that lift the observer off the ground,a central space open to the landscaped and urbanised horizon,and the two anchors which serve as a landmark.These three elements are echoed in the static design of the footbridge,since its end fixing is emphasised and its mass is varied to the point where it appears not to exist at the centre of the structure between its two hinges.

Yangzhou is a major industrial city possessing one of the largest and most modern naval shipyards in China.To echo this industry,the Yangzhou footbridge has been designed like a double sheet of steel forming a box girder of variable cross-section that has been pleated,sheet metal worked and slenderised.

In reference to the advanced metalwork techniques employed in shipbuilding,the geometry of the footbridge has been designed like a sheet of steel,the variations of which follow the path of the stresses across an arch structure,fixed at each end and slimmed where the curvatures are inverted.

The finesse of the structure is revealed by the visibility of the path of stresses and by the pleasure of walking above the canal on this sheet of steel,which varies in both plan and in elevation.

The materials and installation relate the project and its structure to the know-how developed by local industry.The specific character of the footbridge is based on metalwork fabrication techniques,still used today in China.The civil work demonstrates,as one strolls along it,the capacity of its structure to be reduced to a thin sheet of steel.

The links between materiality and form,and between the generic condition of the static and the specific condition of fabrication are manifest in the design.The metalwork techniques common in shipbuilding are employed to express the distribution of the varying load stresses applied to the structure.The old techniques of metalworking are fused with contemporary knowledge in China.

In this footbridge,the forces within the structure are expressed literally by its physical structure.The soft curve of the elevation meets the curve of footpath,which widens towards the centre of the bridge,creating a communal public space at the centre.

The footbridge finds its structural logic in the strength of the shape,which expresses,in the variation of mass,a structure adapted to the requirements of the static design.

Observations of the Sagrada Regia(water lily)leaf have long inspired botanists and structural engineers in terms of the economy of material.It is precisely this frugality that has been sought here in the extremely precise shaping of the lateral box girders,which are of variable cross-section and have been metalworked in relation to the logic of the forces applied.

The people of Yangzhou have named the footbridge "Liu Ye",which means willow leaf,a common species along the canals of Yangzhou.This name would appear to be homage to a design logic nuanced by the fabrication techniques employed.This colloquial naming of the bridge suggests it has already become embedded in both the physical landscape and the social culture of the city.

評論

何可人：揚州，作為古運河的重鎮(zhèn)，本就是橋多，風(fēng)情也多的一座城市。顯然，這座建成于2008年的柳葉橋，橫跨古運河，聯(lián)通兩岸，優(yōu)美如同柳葉，輕盈如同風(fēng)吹柳葉的新橋，得到了揚州人民的喜愛。設(shè)計者在橋的中部加寬了橋面，提供了一個可以稍事停留以觀景和交流的空間，非常自然，而非刻意疊加的過多“說法”，然而又意味雋永。這座橋體現(xiàn)的詩意恰如揚州這座充滿詩意的城市映像，或者說它本身就是一首題詠揚州古運河的詩，純粹和安靜。當(dāng)然，沒有考慮坡道而只設(shè)計了踏步，確實有些缺憾。

張昕楠：一葉之橋

當(dāng)一片葉子彎成一個拱，它便成了一座橋——這是“柳葉”步行橋帶給人的直觀感受。但實際上，這個跨度超過60m，形如一張薄片的拱由5個部分組成：兩個隱藏在地下的橋基，兩個由橋基伸出的引橋和中部的橋面。位于橋身邊緣的側(cè)拱通過在不同部分的翻折變化，與其所在的橋身部分形成箱梁結(jié)構(gòu)，于受力方面加強了橋身各部分的穩(wěn)定性；在形式方面則強化了橋體的整體性和漂浮感；同時也帶來了空間的變化，在橋身中部創(chuàng)造出了更為開闊的空間。

Comments

HE Keren:Yang Zhou,as the important city along the Grand Canal,has always been the stylish town filled with many footbridges.This new "Liu Ye" bridge that links the opposite banks across the canal is as elegant and light as a willow twig in a morning breeze,which has gained much appreciation by local people.The designer widens the surface of the bridge in the middle,which provides a space for sightseeing,rest and communication.The design is natural and meaningful,but not pretentiously "overdone".This bridge represents the poetics of the city"s image,or rather; with purity and serenity,it attaches poemtry to the Grand Canal that winds through Yang Zhou.Of course,it is a bit pity that there are only steps,but not ramps on the bridge.

ZHANG Xinnan:A Leaf

When a leaf bends into an arch,it becomes a bridge–this is the intuitive feeling that the pedestrian bridge "Willow" brings.But in fact,over the span of 60 meters,this sheet-like arch consists of five parts:two abutments hidden underground,two bridge approaches jutting out from abutments,and a central deck.Through various twists and turns,the sidearch at the edge of the bridge and the bridge itself form a structure of box girders,thus strengthening the stability of various parts of the deck while also highlighting the integrity of the bridge and its sense of floating; in the meanwhile,it brings spatial changes,creating a broader space in the middle of the bridge.

4.5縱剖面/Longitudinal sections

6 平剖面/Plan section

7 實景/Bridge view