土建畢業(yè)設(shè)計(jì)外文翻譯--基于結(jié)構(gòu)約束探索不規(guī)則網(wǎng)狀鋼和玻璃外殼形式

1、<p>　　基于結(jié)構(gòu)約束探索不規(guī)則網(wǎng)狀鋼和玻璃外殼形式</p><p>　　Sigrid Adriaenssens, M.ASCE1; Laurent Ney2; Eric Bodarwe3; and Chris Williams4</p><p>　　摘要:在對荷蘭阿姆斯特丹荷蘭海事博物館頂部覆蓋的一種高效的結(jié)構(gòu)形式進(jìn)行探究的文章中，作者簡要討論了作用力對最早的玻璃屋頂覆蓋物的

2、影響。在20世紀(jì)末到21世紀(jì)初，外露的鋼骨架玻璃殼設(shè)計(jì)慢慢出現(xiàn)。這些設(shè)計(jì)形式在從雕塑到幾何再向結(jié)構(gòu)轉(zhuǎn)變。通過荷蘭海事博物館鋼玻璃殼屋頂?shù)陌l(fā)展，對它的挑戰(zhàn)性設(shè)計(jì)的討論得出了設(shè)計(jì)者在基于一個詩意的幾何思想的基礎(chǔ)上，對尋求有效的結(jié)構(gòu)鏈形式的探索。本文提出了一種建筑結(jié)構(gòu)設(shè)計(jì)方法。這種方法稍微適和用數(shù)值模擬方法探索目的是在所有的的三角化、四面性和五面性的網(wǎng)面中實(shí)現(xiàn)平面化的結(jié)構(gòu)鏈模形。然而，如何通過分析玻璃面的途徑將其很好的解決并呈現(xiàn)給人們?yōu)閷?shí)現(xiàn)平

3、面化向人們提出了挑戰(zhàn)。對照此種方法得到麥克斯韋互惠網(wǎng)絡(luò)圖。最后，雕琢出的平面向人們展示了典雅、耐用。</p><p>　　DOI:10.1061 /(土木)ae.1943 - 5568.0000074。©2012美國土木工程師學(xué)會。</p><p>　　CE數(shù)據(jù)庫主題詞:設(shè)計(jì);鋼材;玻璃;古跡;屋頂;荷蘭。</p><p>　　關(guān)鍵詞:形狀;概念設(shè)計(jì);模型

4、探究;鋼玻璃殼體結(jié)構(gòu);歷史意義的庭院;平面化感官;結(jié)構(gòu)約束;麥克斯韋互惠網(wǎng)絡(luò)。</p><p>　　正文：隨著工業(yè)革命的興起,玻璃金屬結(jié)構(gòu)出現(xiàn)受兩個因素支配: 其一、在人口過多的城市, 社會對綠色和安靜的空間的渴望；其二、新的建筑材料(玻璃和鐵) 的出現(xiàn)。</p><p>　　在十八世紀(jì)初,第一溫室裝以玻璃的屋頂出現(xiàn)在人們生活的中。它們的高昂的建設(shè)和維護(hù)成本(由于玻璃和必需的供暖系統(tǒng))讓它

5、們成為精英階層的標(biāo)志。他們的彎曲形狀 [(1) 嵴溝連跨型 例如, 查特斯沃思莊園, 英國(建于1834年), 與(2) 拱形, 例如, 裘園（倫敦市郊著名植物園）, 英國 (建于1844年) (Kohlmaier and Von Sartory 1991)]允許稀疏的陽光進(jìn)入室內(nèi)并照在柑橘和檸檬樹上(因此,名稱橘園)。其他品種的溫室植物、灌木和奇異的植物也被安置在橘園。其中棕櫚樹, 扮演著大量的宗教色彩,是尤其令人印象深刻的和有名的植

6、物,從而也把溫室的形象進(jìn)一步提升。</p><p>　　十九世紀(jì)中期，溫室類型學(xué)已全面發(fā)展，由此便產(chǎn)生了文化室、暖房以及冬景花園[例如, 皇家溫室、拉肯,比利時(建于1876年)現(xiàn)于Fig. 1 (Woods and Swartz 1988)].冬季花園是本文特別感興趣的,因?yàn)樗且粋€社交場合，與一棟私人豪宅或公共建筑及其接近。在十九世紀(jì)下半葉，大規(guī)模生產(chǎn)的負(fù)擔(dān)得起的鐵進(jìn)一步鼓勵了高層和大跨度由鋼材和玻璃建成的展

7、廳的設(shè)計(jì)和施工。大量光線進(jìn)入展覽區(qū)的建筑物，如水晶宮、英國(建于1851年)(如圖所示在Fig. 1)。其如網(wǎng)狀的鋼結(jié)構(gòu)骨架是預(yù)制的，后來被拆除,從海德公園搬運(yùn)至倫敦南部的西登哈姆。不幸的是,它在1936年毀于火災(zāi)。</p><p>　　19世紀(jì)后半期和20世紀(jì)早期，公共建筑物屋頂?shù)脑O(shè)計(jì)和施工又經(jīng)歷了一個很大的提升，冬景花園不再種植植物，而是覆蓋在重要的歷史公共建筑的庭院上方[例如 , 大英博物館的大院子, Un

8、ited Kingdom, 英國; 見 Fig. 1; the Deutschen Historischen Museum, and Museum fur Hamburgische Geschichte, 德國(如期分別在2001和2004年建成的Schlaich Bergermann and Partners); 和the Smithsonian Institute,Washington, DC (Foster and Partner

9、s, and Buro Happold in 2001)]。頂部覆蓋玻璃的單層鋼骨架的形狀由雕塑、幾何、物理以及施工條件等因素共同決定。最近這些結(jié)構(gòu)的重新崛起，伴隨著由數(shù)字化設(shè)計(jì)演化出的工具，使得設(shè)計(jì)師能夠開發(fā)和分析出更多大膽和自由的幾何設(shè)計(jì)。</p><p><b>　　單層玻璃鋼骨架結(jié)構(gòu)</b></p><p>　　今天的設(shè)計(jì)師（有過設(shè)計(jì)和工程背景）在設(shè)計(jì)這些非種

10、植植物的冬季花園時主要遵循以下四個因素: 實(shí)施現(xiàn)狀,建筑美學(xué),建筑幾何形狀和建筑物結(jié)構(gòu)效率等。</p><p><b>　　現(xiàn)代冬季花園</b></p><p>　　在過去的二十年里, 存在著這樣與歷史有關(guān)的公共建筑，它們已經(jīng)能夠通過擴(kuò)展建筑物的中部空間適應(yīng)室內(nèi)或室外氣候。那些狹小的建筑物通常利用中部空間提供光亮。鋼結(jié)構(gòu)玻璃外殼為設(shè)計(jì)的挑戰(zhàn)提供了唯一的解決方案。歷史的

11、顯示，設(shè)計(jì)師在研發(fā)設(shè)計(jì)殼體結(jié)構(gòu)的過程中往往會受到一系列約束條件的限制。其限制條件通常包括高度的限制以及強(qiáng)加于現(xiàn)有建筑物,尤其是水平方向，最大負(fù)荷的限制。大英博物館法院屋頂是滑動軸承支撐,這樣就沒有水平推力落在歷史博物館的砌體墻上(威廉姆斯2001)?；仡欁罱脑O(shè)計(jì)我們就會意識到，推動鋼結(jié)構(gòu)玻璃殼結(jié)構(gòu)設(shè)計(jì)的因素主要是建筑形態(tài)美學(xué)而非結(jié)構(gòu)的性能。</p><p><b>　　建筑美學(xué)</b>&l

12、t;/p><p>　　利用可用幾何數(shù)字建模工具，更多的建筑師通過把他們的工作建立在審美(通常是主觀的)條件上來實(shí)現(xiàn)結(jié)構(gòu)的布景效果。它們的結(jié)構(gòu)設(shè)計(jì)主要取決于結(jié)構(gòu)形式的創(chuàng)新,而非結(jié)構(gòu)的重力荷載條件。因此，這種特殊的設(shè)計(jì)方法可以解決結(jié)構(gòu)缺乏結(jié)構(gòu)效率的問題。不幸的是, 這種結(jié)構(gòu)解決方案通常必須使用一些笨拙的、重要的材料來構(gòu)造這些建筑形態(tài)。這些自由延伸的構(gòu)造會在建筑物產(chǎn)生不利的內(nèi)力，也會在建筑物的表面造成無法預(yù)料的其它不利力的

13、影響。這些形狀依靠彎曲支撐受力-最有效的基本負(fù)荷的方法。然而，設(shè)計(jì)師往往忽略這樣一個事實(shí),即建筑物自由的結(jié)構(gòu)形式由傳統(tǒng)的建筑和結(jié)構(gòu)方式構(gòu)造產(chǎn)生。弗蘭克蓋里,普利茲克獎建筑師, 促進(jìn)了這種建筑設(shè)計(jì)進(jìn)程, 他傳達(dá)過這種建筑設(shè)計(jì)的想法而沒有過這種建筑設(shè)計(jì)(Shelden2002)。一個合理化的設(shè)計(jì)，在初步設(shè)計(jì)階段，需要超越傳統(tǒng)布局經(jīng)驗(yàn)而且要以結(jié)構(gòu)的完整性設(shè)計(jì)為中心(Leach et al . 2004)。</p><p&g

14、t;　　形成一個初步的建筑結(jié)構(gòu)形態(tài)需要一個強(qiáng)大的工程師和承包商團(tuán)隊(duì)。例如, Nuovo Polo Fiera Milano, 意大利 (建于2004年) (Guillaume et al. 2005) 的屋頂殼體設(shè)計(jì)概念是由建筑師馬希米亞諾·福克薩斯,然后交給結(jié)構(gòu)工程師和承包商Mero TSK 集團(tuán)解決結(jié)構(gòu)上和構(gòu)造上的關(guān)系后確定的(見圖 2) (Basso et al. 2009)。</p><p>&

15、lt;b>　　幾何造型</b></p><p>　　幾何學(xué)是一種工具, 古代建筑模型的構(gòu)造就已經(jīng)使用。當(dāng)然，這也一直受到立體解析幾何和設(shè)計(jì)者想象力強(qiáng)加的規(guī)則的限制。幾個世紀(jì)以來,建筑學(xué)已經(jīng)能夠圍繞簡單的幾何圖形來判斷建筑物在結(jié)構(gòu)和構(gòu)造上的質(zhì)量。 [我們可以從花之圣母大教堂的圓頂及其最近的混凝土外殼的設(shè)計(jì)中找到這樣的例子。花之圣母大教堂的圓頂，意大利(建于1436年),由菲利普·布魯內(nèi)萊

16、斯基；其最近的混凝土外殼，費(fèi)利克斯·坎德拉(Moreyra Garlock and Billington 2008)] 旋轉(zhuǎn)彎曲型屋面,移動型屋面,和大小可變型屋面能讓它們更好的組合成殼體屋面結(jié)構(gòu)，并分散成一個個小小的單元。在這種背景下, 耶爾格·施萊希和漢斯·舍貝爾在鋼殼結(jié)構(gòu)的工作是一種創(chuàng)新。他們設(shè)計(jì)了將屋面分為平面四邊形網(wǎng)格方法，能夠獲得正確的移動型屋面,和大小可變型屋面。柏林動物園的HippoHous

17、e，德國（建于1996年），由建筑師設(shè)計(jì)Grieble和Schlaich Bergermann以及合作伙伴(Schober 2002,Glymph et al . 2004)利用這種方法設(shè)計(jì)的一個優(yōu)美的鋼殼,見圖3。</p><p>　　通過結(jié)構(gòu)形式考慮結(jié)構(gòu)效率</p><p>　　幾乎所有傳統(tǒng)的結(jié)構(gòu)設(shè)計(jì)原理(從材料選取、剖面圖,節(jié)點(diǎn)類型, 整體微分幾何、和支撐條件), 整體微分幾何學(xué)都是

18、確定一個殼體結(jié)構(gòu)是否是穩(wěn)定的,安全的,足夠的支撐。每個擁有精美結(jié)構(gòu)網(wǎng)絡(luò)的大跨度殼體結(jié)構(gòu)都是由大量細(xì)小模塊組成。第一個此類結(jié)構(gòu)的設(shè)計(jì)在于設(shè)置精確的邊界條件,在這個精確的邊界內(nèi)外殼的形狀可以向外拓展。在實(shí)現(xiàn)膜強(qiáng)度的穩(wěn)定性，曲線形狀是至關(guān)重要的。彎曲的殼體需要通過尋找“正確”的幾何形狀來避免因自重而只有膜起作用的結(jié)果。薄膜效應(yīng)使材料的性能得以充分發(fā)揮。結(jié)構(gòu)設(shè)計(jì)最重要的的挑戰(zhàn)首先在于確定約束骨架的殼體的三維(3 d)表面。在二十世紀(jì),建筑師和工

19、程師[高迪(Huerta 2003),奧托(Otto et al .1995), 易思樂(Billington 2008)]嘗試?yán)梦锢硇问綄ふ疫@樣一種方法,在對于一個給定的材料,建立一組邊界條件和重力荷載,以尋找有效的三維結(jié)構(gòu)形狀。為鋼殼結(jié)構(gòu)找到一個纜索系統(tǒng)的重要性首先在于這樣一個事實(shí)，自重(鋼和玻璃引起的重力負(fù)載) 主要貢獻(xiàn)的負(fù)載被抵消。子模塊需要軸向加載使截面輪廓最有效地受力。利用數(shù)值模擬形式尋找方法[力密度法(Schek 197

20、4)和動態(tài)松</p><p>　　在NSA庭院競爭設(shè)計(jì)鋼玻璃殼體結(jié)構(gòu)</p><p>　　在不久的將來，荷蘭海事博物館計(jì)劃徹底的改造項(xiàng)目。十七世紀(jì)歷史建筑成為受限空間阻礙了游客的運(yùn)行。博物館的院子需要集成到旅客流通空間,且要規(guī)避天氣影響,保持最小的室內(nèi)溫度。這樣，一個邀請?jiān)O(shè)計(jì)大賽被舉辦，為這座歷史建筑增加更多附加價(jià)值一個新的玻璃屋頂產(chǎn)生了。2005年,奈伊和其合作伙伴,一個總部位于布魯塞爾

21、的工程設(shè)計(jì)咨詢公司, 鋼和玻璃結(jié)構(gòu)外殼設(shè)計(jì)贏得了這次比賽。外殼的制造和施工在2009年和2011年之間。2012年,該項(xiàng)目被授予阿姆斯特丹建筑獎。</p><p>　　Finding the Form of an Irregular Meshed Steel and Glass Shell</p><p>　　Based on Construction Constraints</p&

22、gt;<p>　　Sigrid Adriaenssens, M.ASCE1; Laurent Ney2; Eric Bodarwe3; and Chris Williams4</p><p>　　Abstract: In the context of the search for an efficient structural shape to cover the Dutch Maritime Mu

23、seum courtyard in Amsterdam, Netherlands,</p><p>　　the authors briefly discuss the driving design factors that influenced the earliest glass roof coverings. The trends that emerged during the</p><

24、p>　　late 20th and early 21st century in the design of skeletal steel glass shells are exposed. These design developments range from sculptural to</p><p>　　geometric and structural intentions. The discussi

25、on of the competition design development of the Dutch Maritime Museum steel glass shell</p><p>　　roof shows the quest for a structurally efficient catenary form based on a poetic geometric idea. This paper p

26、resents a construction-driven design</p><p>　　methodology that slightly adapts the numerical form found catenary shape with the objective of achieving planarity in all the triangulated, foursided</p>

27、<p>　　and five-sided mesh faces. The challenge of facet planarity is gracefully solved by an analytical origami approach and presented. This</p><p>　　approach is compared with finding the Maxwell recipr

28、ocal network diagram. The final faceted shape shows elegance and structural efficiency.</p><p>　　DOI: 10.1061/(ASCE)AE.1943-5568.0000074. © 2012 American Society of Civil Engineers.</p><p>

29、　　CE Database subject headings: Design; Steel; Glass; Historic sites; Roofs; Netherlands.</p><p>　　Author keywords: Shape; Conceptual design; Form finding; Steel glass shell; Historic courtyard; Planarity fa

30、ces; Construction constraint;</p><p>　　Maxwell reciprocal network.</p><p>　　Introduction</p><p>　　In the wake of the Industrial Revolution, glass metal structures</p><p&g

31、t;　　appeared as a result of two factors: society’s desire for green, quiet</p><p>　　spaces in overpopulated cities, and the scientific emergence of new</p><p>　　construction materials (glass and

32、 iron).</p><p>　　In the early nineteenth century, the first greenhouses with a</p><p>　　glazed roof appeared as living spaces. Their tall construction and</p><p>　　maintenance costs

33、 (because of the glass and the required heating</p><p>　　system) made them style icons of the elite. Their curved shapes</p><p>　　[(1) ridge and furrow e.g., Chatsworth, United Kingdom (built<

34、;/p><p>　　in 1834), and (2) vaulted, e.g., Kew, United Kingdom (built in</p><p>　　1844) (Kohlmaier and Von Sartory 1991)] allowed the sparse</p><p>　　sunlight into the space and hit th

35、e citrus and lime trees (hence, the</p><p>　　name orangery). Other varieties of tender plants, shrubs, and</p><p>　　exotic plants were also housed in the orangery. The introduction</p>&l

36、t;p>　　of the palm tree, an impressive and prestigious plant with large</p><p>　　religious significance, pushed the shape of the greenhouse further</p><p><b>　　upwards.</b></p&g

37、t;<p>　　In the middle of the nineteenth century, the development of</p><p>　　greenhouse typologies was in full swing, and resulted in culture</p><p>　　houses, conservatories, and winter g

38、ardens [e.g., the Royal greenhouses,</p><p>　　Laeken, Belgium (built in 1876) shown in Fig. 1 (Woods and</p><p>　　Swartz 1988)]. The winter garden is of particular interest to this</p>&l

39、t;p>　　paper because it defines a social meeting place adjacent to a private</p><p>　　mansion or public building.</p><p>　　Mass production of affordable iron in the second half of the</p>

40、;<p>　　nineteenth century further encouraged the design and construction</p><p>　　of tall and large span exhibition halls made of cast and wrought iron</p><p>　　and glass. Plenty of light

41、 entered the exhibition areas of buildings,</p><p>　　such as the Crystal Palace, United Kingdom (built in 1851) (shown</p><p>　　in Fig. 1). Its filigree iron structural skeleton was prefabricate

42、d, and</p><p>　　it was subsequently dismantled and moved from Hyde Park to</p><p>　　Sydenham in South London. Unfortunately, it was destroyed by fire</p><p><b>　　in 1936.</

43、b></p><p>　　The second half of the 20th and the early 21st centuries experienced</p><p>　　a new uprising of the design and construction of roofs over</p><p>　　social gathering pl

44、aces, winter gardens without plants, covering</p><p>　　courtyards of historically important public buildings [e.g., the great</p><p>　　courtyard of the British Museum, United Kingdom; see Fig. 1

45、; the</p><p>　　Deutschen Historischen Museum, and Museum fur Hamburgische</p><p>　　Geschichte, Germany (both Schlaich Bergermann and Partners, built</p><p>　　in 2001 and 2004, respe

46、ctively); and the Smithsonian Institute,</p><p>　　Washington, DC (Foster and Partners, and Buro Happold in 2001)].</p><p>　　The shapes of these glass-covered, single-layered steel skeletal</p

47、><p>　　shells were driven by a combination of sculptural, geometric,</p><p>　　physical, and constructional considerations (Williams 2000). The</p><p>　　recent re-emergence of these str

48、uctures goes hand in hand with the</p><p>　　evolution of digital design tools that enable the designer to develop</p><p>　　and analyze more free and daring geometries.</p><p>　　Sing

49、le-LayeredSteelSkeletalShellsCoveredwithGlass</p><p>　　Today’s designers (either from an architectural or engineering</p><p>　　background) of these nonbotanical winter garden shells seem to</

50、p><p>　　be guided by one or more of the following four driving factors: </p><p>　　Fig. 1. (a) Laeken winter garden (Belgium, built in 1875) still serves as</p><p>　　a social meeting pl

51、ace. (Jackson 2007; reprinted with permission from</p><p>　　the photographer); (b) prefabricated Crystal Palace (United Kingdom,</p><p>　　built in 1851) was dismantled soon after its intended us

52、e (reprinted</p><p>　　from http://commons.wikimedia.org/wiki/File:Crystal_Palace.PNG,</p><p>　　originally from Tallis’ History and Criticism of the Crystal Palace.</p><p>　　1852); (

53、c) British Museum Courtyard (United Kingdom, built in 2000)</p><p>　　steel roof adds value to the museum by expanding the useable circulation</p><p>　　space (image by authors)</p><p&g

54、t;　　imposed existing situation, sculptural architectural esthetics,</p><p>　　geometric shape, and structural efficiency through form.</p><p>　　Imposition on an Existing Situation: The Modern<

55、/p><p>　　Winter Garden</p><p>　　In the last two decades, existing historically relevant public</p><p>　　buildings with a central open courtyard have been adapted to extend</p>&

56、lt;p>　　the useable floor area to an indoor/outdoor climate. These</p><p>　　generally narrow buildings count on the courtyard for daylight.</p><p>　　Steel and glass shells offer a unique solut

57、ion to this design challenge.</p><p>　　The historic context for these shells imposes a series of</p><p>　　design constraints within which the designer has the freedom to</p><p>　　de

58、velop the shell’s form. The boundary conditions often include</p><p>　　height restrictions and limits upon the maximumextra load that can</p><p>　　be imposed on the existing building, particular

59、ly in a horizontaldirection. The British Museum Court Roof is supported on sliding</p><p>　　bearings so that no horizontal thrust is exerted on the historic</p><p>　　masonry walls of the museum

60、(Williams 2001). In the reviewing</p><p>　　the design of recently realized steel shells, the driving design factor</p><p>　　more often seems to be architectural scenographic esthetics rather<

61、/p><p>　　than structural performance.</p><p>　　Sculptural Architectural Esthetics</p><p>　　With the available geometric digital modeling tools, more architects</p><p>　　ba

62、se their work on esthetic (and often subjective) considerations to</p><p>　　achieve scenographic effects. This sculptural design intent can be</p><p>　　appreciated for its inventiveness of plast

63、ic forms, but not for its</p><p>　　consideration of gravity loads. This particular design approach thus</p><p>　　raises questions from a structural point of view with respect to the</p>&

64、lt;p>　　resulting lack of structural efficiency. Unfortunately, the structural</p><p>　　solutions necessary to make these sculptural shapes possible typically</p><p>　　use an awkward and signi

65、ficant accumulation of material.</p><p>　　These free-form shapes often lead to unfavorable internal forces and</p><p>　　under loading do not allow membrane stresses to develop within the</p&g

66、t;<p>　　surface. These shapes then rely on bending action—the least effective</p><p>　　of all basic load carrying methods. Designers often ignore the</p><p>　　fact that the free form is m

67、ade up of conventional constructional and</p><p>　　structural means. Frank Gehry, the Pritzker prize-winning architect,</p><p>　　promotes this architectural process, which expresses sculptural&l

68、t;/p><p>　　intentions but is disconnected from any sculptural intent (Shelden</p><p>　　2002). A rationalization is needed at the preliminary design stage</p><p>　　that goes beyond this

69、 scenographic experience and concentrates on</p><p>　　the structural integrity of the design (Leach et al. 2004).</p><p>　　The evolution of an initial sculptural shape into a constructable</p

70、><p>　　structure needs a strong team of engineers and contractors. For example,</p><p>　　the conceptual design for the shell of the Nuovo Polo Fiera</p><p>　　Milano, Italy (built in 20

71、04) (Guillaume et al. 2005) was developed</p><p>　　by the architect Massimiliano Fuksas and then handed over to the</p><p>　　engineers Schlaich Bergermann and Partners and contractor Mero</p&

72、gt;<p>　　TSK Group for the development of the structural and constructional</p><p>　　rationale for the project (see Fig. 2) (Basso et al. 2009).</p><p>　　Geometric Shape</p><p&

73、gt;　　Geometry is a tool that has been used since antiquity for the development</p><p>　　of architectural shapes. These forms are thus limited by</p><p>　　the rules imposed by analytical geometry

74、 and the designer’s imagination.</p><p>　　Through the centuries, architecture has developed around</p><p>　　“simple” geometries chosen for their constructive or structural</p><p>　　

75、qualities. [Examples can be found in the design of the cupola of</p><p>　　the cathedral Santa Maria del Fiore, Italy (built in 1436), by Filippo</p><p>　　Brunelleschi and more recently the thin

76、concrete shells by Felix</p><p>　　Candela (Moreyra Garlock and Billington 2008).] Surfaces of revolution,</p><p>　　translational surfaces, and scale-trans surfaces lend themselves</p><

77、;p>　　excellently to shell action and discretization into subelements.</p><p>　　In this context, the work of Jorg Schlaich and Hans Schober on steel</p><p>　　shells is innovative. They devised

78、 a method to find the right translational</p><p>　　or scale-trans surface that can be divided into four-sided</p><p>　　planar meshes. The HippoHouse of the Berlin Zoo, Germany (built</p>

79、<p>　　in 1996), designed by architect Grieble and Schlaich Bergermann</p><p>　　and Partners (Schober 2002, Glymph et al. 2004) exploits this approach</p><p>　　in an elegant steel shell, as

80、shown in Fig. 3.</p><p>　　Structural Efficiency through Form</p><p>　　Of all traditional structural design elements (ranging from material</p><p>　　choice, profile sections, node ty

81、pe, global geometry, and support</p><p>　　conditions), global geometry mostly decides whether a shell will be</p><p>　　stable, safe, and stiff enough. The shell spans large distances with</p&

82、gt;<p>　　Fig. 2. Nuovo Polo Fiera Milano (Italy, built in 2004; architect Massimiliano Fuksas, structural engineers Schlaich Bergermann and Partner and Mero</p><p>　　TSK Group) illustrates how a sculp

83、tural shell is discretized in four-sided and triangulated (at the supports) meshes</p><p>　　Fig. 3. Hippo House (Germany, built in 1997), designed by architect Grieble and Schlaich Bergermann and Partners, s

84、hows the discretization of</p><p>　　a translational surface into planar quadrangular meshes (photograph courtesy of Edward Segal, reprinted with permission)</p><p>　　a fine structural network (s

85、keleton) of individual small subelements.</p><p>　　The first design consideration lies in setting the exact boundary</p><p>　　conditions within which the shell shape can be developed. The</p&

86、gt;<p>　　curved shape is of vital importance to achieve stability through</p><p>　　membrane stiffness. Shell bending needs to be avoided by finding</p><p>　　the “right” geometry, so that

87、under the self-weight only membrane</p><p>　　action results. Membrane action makes efficient use of material. The</p><p>　　important structural design challenge lies in the determination of</

88、p><p>　　a three-dimensional (3D) surface that will hold the skeletal shell.</p><p>　　In the twentieth century, both architects and engineers [Gaudi</p><p>　　(Huerta 2003), Otto (Otto e

89、t al. 1995), and Isler (Billington 2008)]</p><p>　　experimented with physical form finding techniques, which for</p><p>　　a given material, created a set of boundary conditions and gravity</p

90、><p>　　loading that found the efficient 3D structural shape. The importance</p><p>　　of finding a funicular shape for steel shells lies in the fact that the</p><p>　　self-weight (gravi

91、ty loads caused by steel and glass) contributes</p><p>　　largely to the load to be resisted. The subelements need to be loaded</p><p>　　axially to make most efficient use of the section profile.

92、</p><p>　　Numerical form finding techniques [force density (Schek 1974)</p><p>　　and dynamic relaxation (Day 1965)] have been successfully applied</p><p>　　to weightless systems who

93、se shape is set by the level of internal</p><p>　　prestress and boundary supports. However, when it comes to funicular</p><p>　　systems whose shape is not determined by initial prestress but<

94、/p><p>　　by gravity loads (such as the case for masonry, concrete, or steel</p><p>　　shells), fewer numerical methods have been developed. This is</p><p>　　mainly because of the diffic

95、ulty of finding optimal forms for those</p><p>　　shells that rely on both tensile and compressive membrane stresses</p><p>　　to resist dead load. Kilian and Ochsendorf (2005) presented</p>

96、<p>　　a shape-finding tool for statically determinate systems based ona particle-spring system solved with a Runge-Kutta solver, used in</p><p>　　computer graphics for cloth simulation. Block and Ochs

97、endorf</p><p>　　(2007) published the thrust network analysis to establish the shape</p><p>　　of pure compression systems. For the initial design competition for</p><p>　　the Dutch M

98、aritime Museum roof project, the dynamic relaxation</p><p>　　method usually used for prestressed systems was adapted to deal</p><p>　　with 3D funicular systems with tension and compression eleme

99、nts</p><p>　　under gravity loads.</p><p>　　Competition Design for a Steel Glass Shell over</p><p>　　the NSA Courtyard</p><p>　　The Dutch Maritime Museum planned a thoro

100、ugh museum renovation</p><p>　　in the near future. The restricted space in the seventeenth</p><p>　　century historic building hinders the movement of visitors. The</p><p>　　courtyar

101、d needed to be integrated into the museum’s circulation</p><p>　　space, sheltered from weather, and kept to a minimal indoor temperature.</p><p>　　An invited design competition was held for a ne

102、w glass roof</p><p>　　that added value to the historic building. In 2005, Ney and Partners,</p><p>　　a Brussels-based engineering design consultancy, won this competition</p><p>　　w

103、ith a steel and glass shell design. The shell manufacturing</p><p>　　and construction processes took place between 2009 and 2011. In</p><p>　　2012, the project was awarded the Amsterdam Architec

104、tural Prize.</p><p>　　Initial Planar Geometry</p><p>　　In the late seventeenth century, the historic building housing the</p><p>　　museum (shown in Fig. 4) was the headquarters of t

105、he admiralship. It was the instrument and symbol of the Dutch maritime power. The</p><p>　　development of this sea-faring nation was closely linked to the</p><p>　　production of sea charts and t

106、he associated sciences, such as geometry,</p><p>　　topography, and, astronomy. The classic building also uses geometry</p><p>　　as a basis for design. The choice for the initial two-dimensional