建筑設(shè)計(jì)與結(jié)構(gòu)設(shè)計(jì)的關(guān)系

金箱溫春

在對建筑設(shè)計(jì)的整體思考中，空間、形式、肌理是由建筑設(shè)計(jì)決定的，而結(jié)構(gòu)和材料則是由結(jié)構(gòu)設(shè)計(jì)所遵循的力學(xué)定律決定的。換句話說，建筑設(shè)計(jì)更偏重視覺領(lǐng)域，而結(jié)構(gòu)設(shè)計(jì)更偏重物質(zhì)領(lǐng)域，兩者的密切關(guān)系尤為重要。在良好的合作中，建筑師會(huì)思考結(jié)構(gòu)，結(jié)構(gòu)工程師也會(huì)思考建筑，這將有利于提升建筑的整體吸引力。本文討論了三種建筑設(shè)計(jì)和結(jié)構(gòu)設(shè)計(jì)之間的關(guān)系，同時(shí)介紹了由金箱結(jié)構(gòu)設(shè)計(jì)事務(wù)所完成的一些結(jié)構(gòu)設(shè)計(jì)實(shí)例。

1 結(jié)構(gòu)設(shè)計(jì)與建筑設(shè)計(jì)同步推進(jìn)——福井季候泥博物館

這是一種令結(jié)構(gòu)工程師激動(dòng)的情況——通過建筑設(shè)計(jì)和結(jié)構(gòu)設(shè)計(jì)來共同決定方案。福井的季候泥博物館便是一個(gè)例子。展出的季候泥是在湖底堆積了7萬年的淤泥，長度綿延49m，展示了過去的天氣及氣候狀況。建筑呈條帶形，9.6m寬、76m長，用來進(jìn)行季候泥的展覽及研究。首層是與景觀相融合的大堂和架空空間。二層是展覽空間，被一堵鋼筋混凝土墻從中間分為6.4m寬和3.2m寬的兩個(gè)空間。屋頂材料應(yīng)客戶要求使用當(dāng)?shù)啬静?。鋼筋混凝土墻和屋頂?shù)牟粚ΨQ性隨之帶來了結(jié)構(gòu)的問題（圖1,2）。

圖3展示了整個(gè)設(shè)計(jì)過程：首先由建筑事務(wù)所制作初版模型，接下來建筑和結(jié)構(gòu)事務(wù)所共同制作分析模型。第一階段討論結(jié)束之后確定了3號(hào)模型的結(jié)構(gòu)體系。在結(jié)構(gòu)概念調(diào)整之后，建筑事務(wù)所制作了4號(hào)模型。最后，雙方共同完成最終模型。在整個(gè)模型制作、研究過程中，兩個(gè)事務(wù)所同時(shí)思考著結(jié)構(gòu)和建筑兩個(gè)領(lǐng)域出現(xiàn)的問題。

在第一次討論會(huì)上，建筑師就提出了建筑整體的造型和功能，圖3-a是當(dāng)時(shí)制作的模型。這是一個(gè)不對稱結(jié)構(gòu)，因此需要水平方向的剛度。但因?yàn)槟窘Y(jié)構(gòu)很難制作剛性框架，因此需要加入對角構(gòu)件。我們討論了結(jié)構(gòu)設(shè)計(jì)中的問題并研究解決辦法。首先，我按照放置對角構(gòu)件或系梁的思路分析了如圖4所示的幾類結(jié)構(gòu)體系。其中，B型體系是最有效率的，但系梁會(huì)影響建筑空間的打造。F型體系設(shè)置了鋼柱預(yù)埋鋼筋混凝土墻，以抵抗水平力。從建筑設(shè)計(jì)角度講，D型和F型是合適的選型。

圖3-b和3-c是由我的工作室制作的可選結(jié)構(gòu)類型的分析模型。我們和建筑師討論了這些模型的建筑空間形象和機(jī)械效率。同時(shí)，建筑師研究了構(gòu)件的布局并制作了相應(yīng)的模型。經(jīng)過與建筑師的充分討論，我們最終選中了如圖3-e所示的D型與F型相組合的結(jié)構(gòu)體系。但是，這一系統(tǒng)還存在著縱向抗震能力差的問題。因此，如圖5所示，一些對角構(gòu)件被加入到傾斜的框架中，以將屋頂?shù)牡卣鸷奢d傳遞給鋼筋混凝土墻。在材料的使用上，如果使用木材，對角構(gòu)件之間的連接將會(huì)非常復(fù)雜，因此使用鋼材。但不管怎樣，結(jié)構(gòu)體系依舊是復(fù)雜的。

最終，我和建筑師再次進(jìn)行了討論，并決定將結(jié)構(gòu)體系改為如圖6所示。原先的體系由木構(gòu)件和鋼筋混凝土墻組成，優(yōu)化后的系統(tǒng)在木屋頂和鋼筋混凝土墻之間加入了鋼構(gòu)件，總體來說較復(fù)雜的構(gòu)件均采用了鋼材。這個(gè)系統(tǒng)的模型由建筑事務(wù)所制作，其中，相對輕巧的鋼構(gòu)件支撐起體積巨大的木結(jié)構(gòu)，由此結(jié)構(gòu)體系和建筑形象均發(fā)生了變化（圖3-f）。

圖7展示了最終的結(jié)構(gòu)體系：木屋頂由膠合木梁和膠合板組成，梁、對角構(gòu)件和柱均采用小尺寸鋼構(gòu)件，鋼筋混凝土墻和樓板由二層的預(yù)應(yīng)力梁支撐。屋頂采用復(fù)合結(jié)構(gòu)，木結(jié)構(gòu)的布置簡潔明了，而其下較復(fù)雜的部分則全部使用鋼構(gòu)件（圖8,9）。

建筑呈條帶形，9.6m寬、76m長，用來進(jìn)行季候泥的展覽及研究。首層是與景觀相融合的大堂和架空空間。二層是展覽空間，被一堵鋼筋混凝土墻從中間分為6.4m寬和3.2m寬的兩個(gè)空間。屋頂材料應(yīng)客戶要求使用當(dāng)?shù)啬静?。鋼筋混凝土墻和屋頂?shù)牟粚ΨQ性隨之帶來了結(jié)構(gòu)的問題。

The building is used for exhibition and research of the varve.Therefore,the shape of the building is belt shape which has width as 9.6m and length as 76m.Material of the roof is wood of the local area requested by the client.Second floor is used for exhibition space,and there is RC wall in the center,which divides space as 6.4m and 3.2m.The asymmetrical relation of RC wall and roof has arisen structural problem.First floor is used for lobby and pilotis which is unified with landscape.

1 福井季候泥博物館室外效果2 福井季候泥博物館二層室內(nèi)效果

首先由建筑事務(wù)所制作最初模型，接下來建筑和結(jié)構(gòu)事務(wù)所共同制作分析模型。第一階段討論結(jié)束之后確定了3號(hào)模型的結(jié)構(gòu)體系。在結(jié)構(gòu)概念調(diào)整之后，建筑事務(wù)所制作了4號(hào)模型。最后，雙方共同完成最終模型。

Firstly,the model was made by the architectural office.Next revised models were made by both offices.And the system as No.3 model was determined aたer the discussion of first stage.Aたer changing structural concept No.4 model was made by architectural office.Final models were made by architectural office and my office.

3 福井季候泥博物館設(shè)計(jì)過程

按照放置對角構(gòu)件或系梁的思路分析了幾類結(jié)構(gòu)體系。其中，B型體系是最有效率的，但系梁會(huì)影響建筑空間的打造。F型體系設(shè)置了鋼柱預(yù)埋鋼筋混凝土墻，以抵抗水平力。從建筑設(shè)計(jì)角度講，D型和F型是合適的選型。

I researched several types of structural system shown.The idea is to place diagonal member or placing tie-beam.Type B is the most efficient,but tie beam disturbed architectural space.Type F is placed steel column embedded RC wall to resist horizontal force.Type D and F is available for architectural design.

4 福井季候泥博物館結(jié)構(gòu)研究

5 福井季候泥博物館對角構(gòu)件布置圖

原先的體系由木構(gòu)件和鋼筋混凝土墻組成，優(yōu)化的系統(tǒng)在木屋頂和鋼筋混凝土墻之間加入了鋼構(gòu)件，總體來說較復(fù)雜的構(gòu)件均采用了鋼材。在這個(gè)系統(tǒng)中，相對輕巧的鋼構(gòu)件支撐起體積巨大的木結(jié)構(gòu)，由此結(jié)構(gòu)體系和建筑形象均發(fā)生了變化。

Previous system is composed of wooden members and RC wall.Improvement system is to place steel members between wooden roof and RC wall,and complicated parts are composed with steel.With this system,not only structural system but architectural image was changed as bigger wooden structure is felted to be supported by small steel members lightly.

6 福井季候泥博物館結(jié)構(gòu)系統(tǒng)的變化

7 福井季候泥博物館結(jié)構(gòu)系統(tǒng)

8 福井季候泥博物館室外效果

9 福井季候泥博物館木梁和鋼構(gòu)件

2 建筑設(shè)計(jì)主導(dǎo)結(jié)構(gòu)設(shè)計(jì)

在一些情況下，建筑師會(huì)優(yōu)先考慮建筑的形象，而結(jié)構(gòu)設(shè)計(jì)的作用只是盡可能完全地實(shí)現(xiàn)建筑設(shè)計(jì)。但即使是在這種情況下，結(jié)構(gòu)設(shè)計(jì)也需要考慮結(jié)構(gòu)效率和結(jié)構(gòu)原則。以下將介紹兩個(gè)項(xiàng)目。

2.1 京都車站中庭

京都車站的設(shè)計(jì)師選自一場國際設(shè)計(jì)競賽。該建筑是一個(gè)大型車站綜合體，包括火車站、酒店、百貨商店和劇院。建筑面積達(dá)23萬m，地上16層，地下3層。在建筑的中心，是一個(gè)由玻璃屋頂和幕墻組成的車站大廳。

圖10 為競賽中建筑師的手繪，展示了車站中庭的效果。左側(cè)為平臺(tái)的入口大門，鋼結(jié)構(gòu)由建筑結(jié)構(gòu)連續(xù)支撐。右側(cè)與車站前廣場相連，墻體的鋼結(jié)構(gòu)由最高達(dá)20m 的組合框架支撐。人們穿過鋼框架，從大廳走到站前廣場。建筑師想要呈現(xiàn)一種特殊的結(jié)構(gòu)效果——由薄鋼構(gòu)件組成的1.44m? 1.44m 的精致網(wǎng)格，而從結(jié)構(gòu)角度來說，過窄的網(wǎng)格是不合理的。建成后中庭的效果幾乎與建筑師的草圖完全一致。結(jié)構(gòu)構(gòu)件是寬100mm，截面為方框的鋼構(gòu)件，各構(gòu)件之間采用焊接的連接方式（圖11,12）。

圖13是鋼結(jié)構(gòu)的橫剖面，橫向均布桁架結(jié)構(gòu)。圖14為鋼結(jié)構(gòu)的立面圖，標(biāo)注了鋼桁架的支撐點(diǎn)。縱向是無格柵構(gòu)件的空腹結(jié)構(gòu)，但是這類結(jié)構(gòu)不足以支撐豎向荷載傳遞，也不足以抵抗地震荷載。因此，在帶狀空間中又加入了格柵構(gòu)件。在這座建筑中，對角構(gòu)件的布置十分重要，雖然有時(shí)與建筑的造型相矛盾，但也可能會(huì)實(shí)現(xiàn)感性的視覺效果。

2.2 青森美術(shù)館

青森美術(shù)館的設(shè)計(jì)靈感來源于槽溝，這種場地形態(tài)在古遺址研究中由線性開挖土壤形成。場地臨近一個(gè)著名的古遺址，挖崛土被放置在建筑的底部，建造的房間被懸掛于上層。槽溝和房間之間被用作展陳空間。因此，展陳空間的形狀和組織較為復(fù)雜（圖15,16）。

這座建筑的結(jié)構(gòu)體系非常復(fù)雜。我曾嘗試著建立結(jié)構(gòu)設(shè)計(jì)的規(guī)則（圖17）。剛性桁架結(jié)構(gòu)位于整個(gè)建筑的頂部空間，由一些通向地下室的結(jié)構(gòu)核心筒支撐，許多房間懸掛其上。當(dāng)懸掛的房間較大時(shí)，便會(huì)加入另一組桁架結(jié)構(gòu)。

圖18展示了由核心單元、屋面矩陣、墻梁和樓板單元組成的結(jié)構(gòu)體系。這個(gè)分析圖同時(shí)也給出了結(jié)構(gòu)設(shè)計(jì)的原則。但是，真正的建筑在三維空間上是非常復(fù)雜的。我們按照規(guī)則布置了結(jié)構(gòu)構(gòu)件，同時(shí)制作了結(jié)構(gòu)模型，用于和建筑師的交流溝通（圖19,20）。

在復(fù)雜的結(jié)構(gòu)中，統(tǒng)一結(jié)構(gòu)構(gòu)件尺寸是非常重要的，立柱和支柱的截面邊長被統(tǒng)一為300mm。圖21展示了施工現(xiàn)場的情況。復(fù)雜的結(jié)構(gòu)系統(tǒng)依舊會(huì)遵循一定的規(guī)則，因此我認(rèn)為通過一些規(guī)則來進(jìn)行控制是非常重要的。

3 結(jié)構(gòu)設(shè)計(jì)主導(dǎo)建筑設(shè)計(jì)

結(jié)構(gòu)設(shè)計(jì)的構(gòu)想有時(shí)會(huì)啟發(fā)建筑設(shè)計(jì)的思路，這同樣令結(jié)構(gòu)工程師十分激動(dòng)。在這種情況下，結(jié)構(gòu)工程師必須對建筑設(shè)計(jì)具有深入的理解。以下將介紹兩個(gè)項(xiàng)目。

10 京都車站中庭手繪圖紙

11 京都車站中庭結(jié)構(gòu)構(gòu)件

12 京都車站中庭室內(nèi)效果

13 京都車站中庭結(jié)構(gòu)橫截面

14 京都車站中庭結(jié)構(gòu)立面

15 青森美術(shù)館室外效果16 青森美術(shù)館玻璃室內(nèi)效果

17 青森美術(shù)館結(jié)構(gòu)設(shè)計(jì)草圖

18 青森美術(shù)館結(jié)構(gòu)分析圖

圖18展示了由核心單元、屋面矩陣、墻梁和樓板單元組成的結(jié)構(gòu)體系。這個(gè)分析圖同時(shí)也給出了結(jié)構(gòu)設(shè)計(jì)的原則。但是，真正的建筑在三維空間上是非常復(fù)雜的。我們按照規(guī)則布置了結(jié)構(gòu)構(gòu)件，同時(shí)制作了結(jié)構(gòu)模型，用于和建筑師的交流溝通。

Figure 18 shows the structural system,which is composed with core unit,roof matrix,wall girder and floor unit.This diagram gives a rule of structural design.But real architecture is 3-dimnsionaliy complicated.We made structural model to show the arrangement structural elements according to the rule.This model was used for the meeting with architects.

19 青森美術(shù)館結(jié)構(gòu)分析模型20 青森美術(shù)館最終版結(jié)構(gòu)模型21 青森美術(shù)館鋼結(jié)構(gòu)施工現(xiàn)場

3.1 群馬蟲世界

圖22是群馬蟲世界建筑設(shè)計(jì)初期的圖紙。場地位于山腳下的斜坡，建筑的整體形象是覆蓋在斜坡上的玻璃薄膜；屋頂?shù)男螤钍怯扇龡l線切割出的球體的一部分。玻璃屋頂下方是蝴蝶的溫室，大混凝土樓梯下方是一些觀察室。這種玻璃結(jié)構(gòu)需要呈現(xiàn)出足夠通透的效果，因此使用了單層的格柵網(wǎng)殼，并且結(jié)構(gòu)構(gòu)件全部本著少而薄的設(shè)計(jì)宗旨。

圖紙只能顯示形式和造型，卻無法說明結(jié)構(gòu)設(shè)計(jì)。設(shè)計(jì)屋頂網(wǎng)格結(jié)構(gòu)時(shí)需要確定溫室條件以及構(gòu)件的截面和連接方式。首先，我本著實(shí)現(xiàn)最優(yōu)空間效果的設(shè)計(jì)原則，切割球體時(shí)，在三個(gè)方向上旋轉(zhuǎn)平面，使其相交于中心點(diǎn)卻互不重合，在表面形成三個(gè)方向的切割線。隨后，我的工作室制作出如圖23所示的結(jié)構(gòu)模型，其中網(wǎng)格長度約為4m，幾乎全部由相似三角形構(gòu)成。在這個(gè)階段，我調(diào)整了屋頂?shù)母叨?，因?yàn)榻ㄖO(shè)計(jì)的屋頂高度過低，以至于無法減少結(jié)構(gòu)構(gòu)件的受力。我希望可以通過減小構(gòu)件尺寸達(dá)到透明的結(jié)構(gòu)效果（圖24）。

接下來，我們開始考慮支撐條件，共研究了四種情況（圖25）：A型在每個(gè)角部設(shè)置三個(gè)支撐構(gòu)件；B型在溫室周圍和角部設(shè)置連續(xù)的支撐構(gòu)件；C型在屋頂周邊設(shè)置V形柱；D型在溫室周圍設(shè)置支撐構(gòu)件并在周邊設(shè)置V形柱。

我們對豎向荷載進(jìn)行了彈性屈曲分析，屈曲系數(shù)如圖26所示：B型結(jié)構(gòu)因?yàn)榇嬖诰植看罂缍瓤臻g，體系抗屈曲效率不高；在周邊布置V形柱的C型體系非常高效；D型體系被認(rèn)為是最適合這一結(jié)構(gòu)的支撐方式，同時(shí)構(gòu)件尺寸也被最小化。我將確定的結(jié)構(gòu)網(wǎng)格和支撐方式提交給建筑師，他接受了我的建議并確定使用V形柱（圖27）。格柵構(gòu)件管徑在中心區(qū)域?yàn)?56mm、在周邊區(qū)域?yàn)?00mm，V形柱的構(gòu)件管徑為300mm。連接構(gòu)件使用的是如圖28所示的鑄鋼。玻璃由DPG及點(diǎn)狀玻璃直接固定在主體結(jié)構(gòu)構(gòu)件上。該屋頂沒有二級結(jié)構(gòu)，非常簡單和通透（圖29）。

3.2 國營昭和紀(jì)念公園花與綠文化中心

國營昭和紀(jì)念公園花與綠文化中心是一個(gè)位于公園內(nèi)的多功能建筑，平面長150m、寬30m。設(shè)計(jì)概念是打造一個(gè)位于公園內(nèi)，朝向天空的帶狀綠色空間。建筑內(nèi)部種滿樹木和各類植物。屋頂是一個(gè)不規(guī)則的傾斜曲面，成為建筑造型的特色所在。

22 群馬蟲世界平面和立面

23 群馬蟲世界穹頂結(jié)構(gòu)模型24 群馬蟲世界玻璃穹頂室外效果

25 群馬蟲世界支撐條件

26 群馬蟲世界彎曲分析結(jié)果

27 群馬蟲世界建筑模型28 群馬蟲世界鑄鋼連接構(gòu)件29 群馬蟲世界玻璃屋頂

屋頂由兩種結(jié)構(gòu)支撐。一種是鋼筋混凝土的環(huán)形白墻，另一種是圍合成圓柱的白鋼柱，這些構(gòu)件被統(tǒng)一稱為圓柱體。地震力僅由鋼筋混凝土墻體抵抗。圓柱體則被隨機(jī)地布置于屋頂之下（圖30），內(nèi)部是特定的功能空間，外部是靈活的功能空間。鋼筋混凝土圓柱的布置需要在平面上尋求一個(gè)良好的平衡。

屋頂?shù)脑煨蛶缀跏瞧降?，其上種滿了樹木和各種植物。由于彎矩在設(shè)計(jì)中占主導(dǎo)地位，因此采用鋼桁架結(jié)構(gòu)，通過平面網(wǎng)格、整體起伏、局部起伏三個(gè)步驟，確定屋頂?shù)脑煨图捌錁?gòu)件的平面布置。

項(xiàng)目采用平面網(wǎng)格的設(shè)計(jì)方法。圖31是屋頂桁架平面圖，圓圈表示支撐屋頂?shù)膱A柱體。連接多個(gè)圓柱體的中心點(diǎn)形成三角形，內(nèi)部又再次進(jìn)行分割，因此網(wǎng)格的邊長趨近相同。徑向構(gòu)件從每個(gè)圓柱體展開，并且在另一個(gè)方向上連接到其他的構(gòu)件。該網(wǎng)格結(jié)構(gòu)利于傳遞豎向荷載。

屋頂采用連續(xù)扭轉(zhuǎn)的條帶造型。我們將縱軸方向上正弦和余弦曲線的振幅確定為1.5m，進(jìn)而確定屋頂兩端的高度，然后用一條直線連接屋頂兩端，形成曲面，最終通過幾何分析確定屋頂?shù)恼w起伏造型。

最后一步是確定屋頂局部起伏造型(圖32)。圓柱支撐桁架的彎矩在靠近連接處較大。彎矩的分布決定了桁架的高度，因此桁架在大多數(shù)位置的高度為2.5m，在靠近圓柱體的位置會(huì)增高1m，即上弦桿件在圓柱體附近會(huì)被提高1m。屋頂?shù)拇蟛糠謪^(qū)域被厚度約為300mm的土壤覆蓋，土壤的厚度依桁架上弦桿件的起伏而發(fā)生變化，圓柱體頂部連續(xù)傾斜的地形，會(huì)形成深約1.2m的護(hù)坡，在這些位置，也會(huì)種植高大的樹木。

這個(gè)體系的概念源自于結(jié)構(gòu)思想，實(shí)現(xiàn)了結(jié)構(gòu)設(shè)計(jì)、建筑設(shè)計(jì)和景觀設(shè)計(jì)的統(tǒng)一。圖33是按上述步驟制作的半屋頂模型。雖然每個(gè)步驟都很簡單，但當(dāng)他們結(jié)合在一起的時(shí)候，就會(huì)有一些復(fù)雜。

對構(gòu)件和細(xì)部的設(shè)計(jì)同時(shí)考慮到了制作水平。在連接處垂直放置直徑為150mm的鋼管，桁架的弦構(gòu)件和格柵構(gòu)件采用200mm寬的T形桿件，被連接到用高強(qiáng)度螺栓連接的扣板上。不規(guī)則形狀的桁架通過控制扣板的形狀和位置以及桁架構(gòu)件長度完成建造，使所有桁架用相同方式連接（圖34-37）。

4 結(jié)論

本文共討論了三種結(jié)構(gòu)設(shè)計(jì)和建筑設(shè)計(jì)的關(guān)系。在每個(gè)項(xiàng)目里，這兩者的關(guān)系是不同的。但即使是在建筑設(shè)計(jì)的過程中，當(dāng)建筑和結(jié)構(gòu)的合理性產(chǎn)生矛盾時(shí)，結(jié)構(gòu)設(shè)計(jì)的自身邏輯也是需要被尊重的，并且結(jié)構(gòu)工程師必須要始終追求結(jié)構(gòu)效率并實(shí)現(xiàn)結(jié)構(gòu)形式的優(yōu)雅性。

30 國營昭和紀(jì)念公園花與綠文化中心平面圖

31 國營昭和紀(jì)念公園花與綠文化中心鋼桁架平面網(wǎng)格

32 國營昭和紀(jì)念公園花與綠文化中心屋頂局部起伏造型

33 國營昭和紀(jì)念公園花與綠文化中心桁架結(jié)構(gòu)模型

34 國營昭和紀(jì)念公園花與綠文化中心連接體系35 國營昭和紀(jì)念公園花與綠文化中心施工現(xiàn)場

36 國營昭和紀(jì)念公園花與綠文化中心建成屋頂局部37 國營昭和紀(jì)念公園花與綠文化中心室外效果

1-7,9,11-37 金箱結(jié)構(gòu)設(shè)計(jì)事務(wù)所提供

8 內(nèi)藤廣建筑設(shè)計(jì)事務(wù)所提供

10 原廣司＋Atelier Phi 建筑研究所提供

Thinking about architectural design,space,form and texture are created by architectural design,on the other hand,frame and material are determined with obeying dynamics by structural design.In another word,architectural design is an image field,and structural design is a really field.It is important that both fields make close relationship.In a good relationship,an architect thinks about structure and an engineer thinks about architecture.The close relationship between architect and structural engineer creates enhancement of architectural attraction.Three types of structural design in attention of relationship to architectural design are considered in this paper.Several structural design practices which I designed are introduced.

This case is exciting experience for structural engineer.The design is determined from not only architectural aspect but structural aspect.One example is a museum of varve at the local city in Japan.Varve is an accumulated mud at the bottom of a lake for 70 thousand years,which has 49m in length and shows the state of weather and climate condition in the past time.The building is used for exhibition and research of the varve.Therefore,the shape of the building is belt shape which has width as 9.6m and length as 76m.Material of the roof is wood of the local area requested by the client.Second floor is used for exhibition space,and there is RC wall in the center,which divides space as 6.4m and 3.2m.The asymmetrical relation of RC wall and roof has arisen structural problem.First floor is used for lobby and pilotis which is unified with landscape (photo 1,2).

Figure 3 shows the process of design.Firstly,the model was made by the architectural office.Next revised models were made by both offices.And the system as No.3 model was determined aたer the discussion of first stage.Aたer changing structural concept No.4 model was made by architectural office.Final models were made by architectural office and my office.Models were made and structural and architectural viewpoints were confirmed in both offices simultaneously.

Architectural image and function were shown by the architect at the first meeting.We talked about structural problems and how to solve the problems.I researched several types of structural system shown as figure 4.Photo 3-b and 3-c are Skelton models of structural available type made by my office.I discussed with the architect about space image and mechanical efficiency of these models.At the same time architect researched the arrangement of members and made some models.Aたer discussion with the architect combined system type D and F shown as photo 3-e were selected.But this system had another problem about earthquake resistant of the longitudinal direction.Some diagonal members were needed in the slanted frame shown in figure 5 to transfer the earthquake load of the roof to RC wall.If the diagonal members were used wood,connection of members would be complicated.we thought to use diagonal members with steel.Anyway,structural system was complicated.

I and architect discussed again and decided to change structural system shown as figure 6.Previous system is composed of wooden members and RC wall.Improvement system is to place steel members between wooden roof and RC wall,and complicated parts are composed with steel.The model of this system was made by the architect's office (photo 3-f).With this system,not only structural system but architectural image was changed as bigger wooden structure is felted to be supported by small steel members lightly.

Figure 7 shows the final structural system.The wooden roof is composed of glulam beam and plywood panel.Beams,diagonal members and columns are used steel member.Steel members are small size.RC wall and slab are supported by prestressed beams of the second floor.The structure of roof is composite structure.Arrangement of wooden structure is simple and easy;the complicated part is used with steel member.Complicated details are used only in steel members (photo 8,9).

In some cases,architectural image precedes and the role of structural design must be to realize architectural design faithfully as possible.But even if in such a case,structural design is needed to think about structural efficiency and structural rule.Two projects are introduced.

2.1 Atrium in Kyoto Station

Kyoto is the ancient capital of Japan.The architect of this building was selected by an international design competition.This building is a large station complex,which has train station,hotel,department store,and theatre.It includes 16 floors,3 basement floors and has 230 thousand square meters of floor area.In the center of the building,there is a concourse,which was covered with glass roof and wall.

Figure 10 is the image drawing of the atrium,which was drowned by the architect for the competition.There is the entrance gate of the platform at the leた side,and the steel structure is supported by building structures continuously.The right side is connected to the plaza in front of the station,and the steel structure of the wall is supported by combined frames as the pitch of 20m.The architect wanted to make a special structure,which has delicate grid as 1.44m by 1.44m and composes with thin steel members uniformly.This image is not structurally rational because the grid is too narrow.The image of architecture is almost fit to the sketch of the architect.The structural member is 100mm wide steel square box section,and the members are connected by welding (photo 11,12).

The basic arrangement of the longitudinal structure is Vierendeel structure without lattice members.But the strength of this type structure is not enough to transfer vertical load to the support points and to resist seismic load.Therefore,lattice members are added at belt shape zone in order to transfer load to the support point and to resist seismic load (figure 13,14).In this architecture,arrangement of diagonal member is important.Placing diagonal members partially are in conflict with uniform image of architecture,but it is possible to realize architectural sensitive image.

2.2 Aomori Museum of Art

The next example is Aomori Museum of Art shown as photo 15 and 16.The motive of design of this architecture was arisen from Trench,which is the condition of digging soil linearly for researching ancient ruins.The

site is located near a famous ancient ruin,so Trench was selected a motive.Digging soil is placed at the lower part of the building and artificial rooms are hung from the upper structure.The spaces between trench and artificial rooms are used for exhibition space.Therefore,the shape and arrangement of exhibition space is complicated 3-dimensinally.

The structure system of this architecture must also be complicated.I tried to establish the rule of structural design.Figure 17 is the idea of structural design for this architecture.The rigid truss structure is placed at the whole area of the top of the building.The truss is supported by several structural core stranded from basement.Many rooms are hung from roof truss.When the volume of hanged room is bigger,other truss structures are added at the hung rooms.Figure 18 shows the structural system,which is composed with core unit,roof matrix,wall girder and floor unit.This diagram gives a rule of structural design.But real architecture is 3-dimnsionaliy complicated.We made structural model to show the arrangement structural elements according to the rule.This model was used for the meeting with architects (photo 19,20).

It is important to unify structural element size with complicated structure.Columns and bracing were unified the size as 300mm.Photo 21 is the scenery of construction.The structural system became complicated finally,but it is obeyed a rule.I think even if the structure is complicated,it is important to control with some rules.

Sometimes structural thinking arises architectural design idea.It is exciting situation for structural engineers.Structural engineers must deeply understand for architectural design in this case.Two projects are introduced.

3.1 Gunma Insect World

Figure 22 is the architectural drawing in basic design phase.The building site is in a slope at the base of a mountain.The image of the architecture is a thin glass membrane covered on the slope;the roof shape is cut part of a sphere by three lines.There is the hothouse for butterflies under the glass roof.There are several observation rooms under the concrete large stair.This glass structure was needed transparency,therefor the structure is single layer lattice shell,and the structure members were hoped less and thin.

This drawing indicated form and image,but didn’t indicate structural element.On structural design,making grid of the roof,determining support condition considered the hothouse,and determining member section and connection were needed.Firstly,I tried making the grid of the roof considering to appear the perimeter zone elegant.Rotating planes in three directions as cutting the sphere makes three direction lines at the surface of the sphere.Three lines cross the same point at center area,but are not coincident at perimeter area.The lines are arranged to coincident the cross point of the three lines.Aたer that,three-dimensional structural model showed photo 23 was made in my office.The grid length is about 4m.The shapes of triangle are almost the same form.In this stage,I arrange the height of the roof,because the height of the roof of architectural drawing is too low to reduce stress of members.I wanted to make member size smaller to realize a transparent structure (photo 24).

Next,the support condition was considered.Four cases of support condition were considered (figure 25).

Type A:There are three supports at each corner.Type B:There are continuous supports around the hot house and corners.Type C:There are the V shaped columns in the perimeter of the roof.Type D:There are supports around the hot house and the V shaped columns in the perimeter.

The elastic buckling analysis about vertical load was done and the buckling coefficient is shown in figure 26.The support of type D which is used vertical columns around the hothouse and V shape columns in the perimeter is thought suitable for this structure.The member size was minimalized by this structural system.I proposed to the architect the structural grid and the support condition.He accepted my proposal and made the design using V-shaped columns(photo 27).The member of lattice is pipe as 256mm diameter at the center area and pipe as 500mm diameter at the perimeter,and the member of V-shaped column is pipe as 300mm diameter.Connection is used with cast steel shown as photo 28.Glasses are fixed directly (on) main structural member by DPG,dot point glazing.There is not secondary structure.It is very simple and transparency roof (photo 29).

3.2 Showa Kinen Park Hanamidori Cultural Center

Another example is Showa Kinen Park Hanamidori Cultural Center.The building,which was planned within a park,is a multiuse facility with a 30m wide by 150m long planar size.The architectural design concept is a band of green space within the park;liたed upward toward the sky with trees and various plants.The building has irregularly shaped rooたop that incorporates slanted and curved surface.

The roof is supported by two types of the structure.One is white walls with cylinder shape made of RC,another is aggregates of white steel columns with cylinder shape.These elements were named cylinder.Seismic force is resisted only by the RC wall-structured cylinders.The cylinders were placed at random under the roof (figure 30).The inside of the cylinders are specific function spaces,the outer of the cylinders is provided flexible functions.It was important to place the RC wall cylinders in a good balance planarly.

The roof is configured so as to be nearly flat.There are plants and trees on the roof.Because the bending moment is dominant,a steel truss structure was used.The roof configuration and the layout of the members were important for this project and it was determined through the following three operations:planar grid,overall undulation of the roof and localized undulation shape of the roof.First,method of making planar grid is introduced.Figure 31 is the plan of the roof truss.The circles indicate cylinders which support roof.A triangular shape that joined the center points of multiple cylinders was formed,and the inside of each triangle was divided so that the length of the grid

was almost equal.A radial direction member expands from each of the cylinder,and connects to the member from other direction.This grid fits the flow of force for vertical load.

The overall undulation shape of the roof is continuously twisted belt.The height of both ends of the longitudinal direction were determined by sine and cosine curves with amplitude of 1.5 m.Then both ends were connected with a straight line to form surface.The undulation of the overall roof shape was determined with geometry.

Finally,the localized undulation shape of the roof is determined (figure 32).The bending moment diagram of the truss supported by the cylinder is bigger near the cylinder.If the height of the trusses is determined by the distribution of the bending moment,the height of the truss in general portions was 2.5m,and the height of the truss near the cylinder added 1m.The upper chord members are liたed 1m near the cylinder.The roof was covered with soil to a thickness of about 300mm in general areas.The soil level was also varied in accordance with the undulation of the upper chord members of the trusses,and an incline was continued at the top of the cylinders to create an embankment of about 1.2m depth.Large woods were planted in these portions.

This system was introduced from structural idea,and the structural design,the architectural design and the landscape design were unified by this method.Photo 33 is the model of half of the roof based on the rules.The three rules are simple,but when those rules are combined the result is a little complicated.Member components and details were designed in consideration of the fabrication.Steel pipes having a diameter of 150mm were placed vertically at the connection.The chord members and lattice members of the trusses were used a 200mm wide series of T-section members.T-section members were attached to gusset plates connected with high strength bolts.The irregularly shaped trusses were built by controlling the shape and positioning of the gusset plates and the length of the truss members.The basic method to make truss connection is only one type (photo 34-37).

Three types of structural design are considered in attention of relationship to architectural design in this paper.The relationship structural design and architectural design is variable in every project.Even if architectural design proceed has contradiction of structural rationality,philosophy of structure design is needed,and structural engineers must seek structural efficiency and realize structural elegancy.