結構中力的傳遞路徑應該是清晰可見的，這也是sbp的結構工程師在設計中所希望展現的結構的可讀性。只有當建築用材與構件截面在形式上不被強制規定的時候，才可對結構體系進行發展，針對結構自身特性進行相應地設計與建造。
The force path in the structure should be clear andreadable, which is also what sbp has been striving to do. Existing structuresystem could achieve great improvement only when there is not much compulsiveboundary conditions for the materials and element sections.
© sbp / Marcus Bredt
五月末六月初，歐洲冠軍聯賽剛結束，馬上又將迎來世界盃的哨音。本期特稿將向大家介紹由sbp公司首創而且不斷在眾多的體育場館中設計中頻繁採用，並結合不同項目環境條件下不斷創新發展的典型輕型結構體系——環索屋蓋結構體系及sbp設計的一些採用該結構體系的世界著名體育場。
It’s now end of May and the beginning of June. The UEFAChampions League just finished its final game and there comes the whistle forthe games of World Cup. This time we are going to give a brief introductionabout a typical light structure- Ring cable roof structure, which is originally created and further developed by schlaich bergermann partner, and has been frequently used in lotsof stadiums. In this article you will also see how this structural system hasbeen successfully applied in famous stadiums that are designed by sbp.
預應力鋼索可以在耗費很少材料的情況下實現很大的結構跨度，但對於索網結構而言，其對應於索的錨固而產生的造價會很高。鋼索端部的錨固是實現索網結構樣式多樣化的前提，但是這需要耗費大量的錨固基礎，索網扣件、錨固件等。
Prestressed cable structures span wide with a minimumof materials, but are expensive if they are back-anchored and finely meshed.Back anchoring is a prerequisite for the variety of possible forms, but it requiresgigantic foundations and the fine meshing involves numerous costly cable clampsand anchorages as well as covering.
環索屋蓋結構充分發揮了預應力鋼拉索結構的優良特性且規避了其短處，其結構構造類似於輪輻。輪輻由截面較薄的輪輞結構，大量輻條和一個中央輪軸組合而成。剛度很小的輪輞在單獨工作的時候很小的外力就可以讓其產生屈曲。通過輻條的預張拉後，輪輞的剛度則得到了很大的加強。
The Ring cable roof structure maximizes the favourablestructural performance and minimizes the unfavourable shortcoming of cablestructure. It is working like a spoke wheel. A spoke wheel is composed of a rimwith thin section, some spokes and a wheel spindle in the center. The rim wouldeasily get buckling problem when it is bearing any external forces as aconsequence of the small stiffness. But while the three components work as aintegration, the stiffness is hugely strengthened as the spokes are prestressedand thus bring the rim into another internal force status.
在環索屋蓋結構中，結構外圈設置的封閉的壓環擔起了輪輞的角色，結構內圈的封閉預應力拉環則起著類似於中央輪軸的作用。壓環和拉環之間通過按一定間距布置的徑向拉索連接。拉環中的預應力在放射狀分布的徑向拉索上產生拉力。徑向拉索內的拉力傳遞到外環上在外環內部產生壓力。預應力在這一輕型結構中的的作用就是提高整個屋蓋結構的剛度 ，從而減小屋頂結構的位移和屋頂的振動以及非均勻荷載下的抗壓環彎曲變形。拉索不但可以向抗壓環傳遞荷載而且能起到穩定抗壓環的作用。最終拉環、壓環與其間的鋼拉索一道構成了該內力自平衡的「自錨」形式環索屋蓋結構。
In a Ring cable roof structure, the compression ringwhich is usually placed at the perimeter of the stadium takes the role of therim in the spoke wheel while the prestressed tension ring in working as thewheel spindle in the center. Radial cables were used to connect the compressionthe and the tension ring. Compression ring is applied in this system so thatradial cables can be anchored to the compression ring, and thus theprestressing force will be balanced within the roof structure system. Likewise,tension ring is applied in this system so that the big opening in the middle ofthe roof is realized and the prestressing force in the tension ring stablizesthis whole system. Thus the roof structure is a self-anchored system. Theself-anchored spoked-wheel roof is placed on vertical support columns and formsthe most economic structural system for wide-span stadium roofs. Furthermore,the slender cable can barely be seen and thus makes a light and elegant stableroof.
根據實際項目屋蓋造型、屋面覆蓋材質等的不同，環索屋蓋結構體系演變出了兩個壓環一個拉環、一個壓環兩個拉環、一個壓環一個拉環等不同的類型以滿足建築需要。
Depending on the architectural appearance and thecovering materials and so on, there are several types of Ring cable roofstructure options while sharing the same principle of mechanics.
巴西馬拉卡納體育場是為1950年巴西世界盃而興建的一座足球場，它在建成時能夠容納20萬名觀眾觀看球賽，是當時世界上最大的體育場。馬拉卡納的名氣，不僅僅來源於它的規模，馬拉卡納同時見證了許多頂級賽事、頂級球員輝煌時刻以及足球史上的一些難忘瞬間。球王貝利在馬拉卡納體育場打進了他效力巴西國家隊的第一個進球，也是在馬拉卡納體育場打進了他為國家隊效力的第1000個進球。1950年7月16日，相當於裡約熱內盧1/10人口數量的觀眾湧入了馬拉卡納體育場，含淚在自己家門口見證了巴西隊在世界盃決賽上以1:2輸給了烏拉圭。
The stadium Maracanã was erected to host the World Cupin 1950 and was the largest stadium in the world with a capacity of 200,000spectators. This is however, not theonly reason for its fame. Its mythical status can be attributed both to the legendary matches and players that it hashosted –Pelé scored his first goal for the nation here and, years later, his thousandth goal as a professional player – as well as some of themost traumatic moments in Brazilian football it has witnessed: on July 16th, 1950, almost a tenth of Rio’s population was in the Maracanã and broke downin tears as Brazil lost the World Cup final 1:2 to Uruguay.
為了迎接2014年世界盃以及2016年夏季奧運會，馬拉卡納體育場於2010年3月開始重修工程。馬拉卡納體育場需要做出一系列的改造以滿足國際足聯對世界頂級賽事舉辦體育場的相關要求。體育場的上層觀眾席被進行了加固翻新，而下層的觀眾席則直接進行了拆除重建以確保更好的觀賽視角。對於當時的馬拉卡納體育場重修工程，其中的一個主要問題是屋頂：其混凝土結構的懸挑屋蓋只能夠最大限度地為現場45%的坐席起到遮擋作用。
As is to host the World Cup in 2014 and the SummerOlympic Games in 2016, Maracanã started reconstruction to fulfill FIFA standards. The upper spectator tier wasrenewed and the lower tier completely rebuilt with improved sight lines. Themain problem, however, was the roof: a concrete construction that cantileveredforward just enough to cover 45 percent of the seats.
一開始的時候，設計師打算保留既有的屋蓋結構並將其向體育場內側進行加固延伸。但是很快他們發現這些已經建造了半個世紀之久的混凝土懸挑梁既無法被加固，也無法繼續提供足夠強度滿足當前結構需求。同時，原有結構上再建造新的屋蓋結構也被否決了，因為這樣會改變體育館的外觀，這是不被允許的。最終sbp的工程師提出一個環索屋蓋結構解決方案，這個屋蓋在結構高度是如此的小以至於它可以作為一個整體嵌入原混凝土結構而不改變這個世界聞名的足球場的外觀輪廓。馬拉卡納球場的環索屋蓋結構由一個外圈壓環，三個拉環以及兩者之間的徑向拉索組成。為了放置該環索屋蓋，舊的混凝土屋蓋懸挑梁被移除。對應於下部混凝土結構環形布置的60根混凝土柱，環索屋蓋結構也分成了60個單元，其截面尺寸為1m x 2m的外圈壓環就放置於混凝土柱頂。這60個連接節點中有52個是不傳遞橫向力的，風荷載等引起的水平力僅通過4對對角切向布置的錨固件傳遞給下部混凝土結構。
At first the planners pursued the strategy ofextending the existing roof coverage inward, retaining the existing roofconstruction. But the existing concrete cantilevers, now more than half centuryold, could neither be strengthened nor were they capable of supporting theroof. It was not possible to add a new roof structure as it would have alteredthe stadium’s appearance. Finally the engineers at schlaich bergermann undpartner developed a roof construction that was so flat that it could beinserted into the historical construction without altering its iconicsilhouette. The approach applies a new variant of the spoke-wheel principleemploying a compression ring around the perimeter, three inner tension ring andsome radial connection cables as the spokes. The cantilever arms were removedas to make space for the newly introduced roof. The sixty columns of theexisting structure correspond to the sixty segments of the roof, while thespoke-wheel roof lies like a rigid lid, the one by two meter cross-sectionhollow beam of the compression ring resting on the tops of the sixty columns,fifty-two of which do not produce transversal forces. Horizontal forcesresulting from wind loads are dissipated only via four pairs of diagonallyarranged tangential anchor points.
▲馬拉卡納體育場 – 改造前 before renovation (photoby: Reprodução)
▲馬拉卡納體育場 – 改造後 after renovation © sbp/Marcus Bredt
新建的屋蓋結構通過徑向距內環1/3跨度的位置設置飛柱的方式來加強整個屋蓋結構的穩定性和剛度，結構中引入飛柱後得到了類似非常形狀的索桁架結構，在索桁架的外最外側為壓環，而在剩餘的三個內部的角點上則均為環形索構成的拉環。這個高度達到13.5米的梭形飛柱上還設置了檢修馬道及其他的設備。這個各處均向內懸挑了68米的屋蓋的總重量為4000噸，而每平米的用鋼量在90千克左右，因此本結構是名副其實的輕型結構。
The stability of the cable-net roof and the overallstiffness of the roof system is achieved by employing flying struts to holdapart the array of cables about two-thirds of the way into the roof, creatingflattened kite-shaped cable truss with one compression ring and three tensionring at its corners. Catwalk path and some technical installations were hang onthe 13.5-meter–high flying strut. The roof extend evenly 68 meters from allsides into the oval of the stadium. Weighting a total of approximately 4,000tons, equivalent to 90 kilograms per square meter, it is an extremely lightweightconstruction.
▲馬拉卡納球場-飛柱及索桁架示意 (rendering: schlaich bergermann partner)
© sbp/Marcus Bredt
© sbp/Marcus Bredt
建築師：gmp- Von gerkan Mark und partner
看臺結構設計-Daniel Fernandes.
業主方：EMOP,Rio de Janeiro
結構形式：輪輻式工作原理的環索屋蓋
長度：295m 寬度：258m
面積：46,500m2 座位：77,000個
竣工時間：2013年6月
位於烏克蘭的基輔國家奧林匹克體育場的前身叫做 「列夫託洛斯基紅館」。在20世紀20年代初，基輔當地建造了這座「紅館」用以舉辦第二屆全烏克蘭奧林匹克運動會。建造完成至20世紀末，這座體育館幾經改名和修整重建。2007年，波蘭和烏克蘭聯合申辦歐洲杯成功，並決定將決賽場地設置在烏克蘭的首都基輔，於是基輔市在原體育場既有結構的基礎上改造建設了基輔國家奧林匹克體育場。
At the beginning of the nineteen-twenties, the 「Redstadium Lev Trotzky」 was built to host the Second All-Ukrainian Olympic Gamesin 1923. This is the origin of the Olympic Stadium, Kiev. During the following80 years after the lifting up, it hasbeen reconstructed and renamed for several times. In the year 2007, thedecision to award the European football championship in 2012 to Poland and Ukrainepresented the city of Kiev with a new challenge. The cup final was to takeplace in the Ukrainian capital, so the city reconstructed the sports complexand naming it as Olimpiysky.
基輔國家奧林匹克體育場 - 改造前 (photo by: René Hoeflaak)
基輔國家奧林匹克體育場保留了大部分建於1968年的的原混凝土看臺結構，屋蓋結構則通過設置在看臺結構外圍的鋼結構立柱進行支撐，這樣避免了將屋蓋結構的自重和承受的外力直接作用到原混凝土結構及其下部基礎上去。鋼結構立柱的數量以及空間布置遵循了原看臺結構混凝土柱的布置原則，原結構的80條徑向軸線上對應設置了80根支承屋蓋的鋼結構柱。在鋼結構立柱上，採用了設置2個外圈壓環和1個內圈拉環的輕型環索屋蓋結構，屋蓋頂部通過張拉膜進行覆蓋。對於該體育場，由於設置了環繞足球場的跑道，且該跑道在長軸方向為長直線，在短軸方向為半圓弧，這樣的設置在一定程度上定義了整個體育場的幾何形狀，而如此的幾何形狀對於拉壓環結構來說較為不利，因為該幾何形狀的曲率變化較大，而拉壓環的曲率對結構內力有很大的影響。對於這種情況，結構設計師將支承屋蓋的鋼結構柱設計成了在半柱高位置向內折的折線形式，且對於沿體育場長軸兩側布置的鋼結構柱，其折角較小，而對於沿著體育場短軸兩側布置的鋼結構柱，其折角則較大，如此一來，較之體育場內場的幾何形狀，鋼結構柱的頂點閉合環和中間折點閉合環的在幾何曲率上有了更好的連續性，而這兩個閉合環即可以很好的作為屋蓋結構的兩個外圈壓力環。
▲折線形鋼結構梁以及上下兩個壓環 (圖片來源：JaegerF., Next 3 Stadia (p.100),2012)
The historically listed upper tier built in 1968 wereretained till now in Olimpiysky whilethe roof structure have to be built around the existing bowl of the stadiumwithout touching it. For the design of the roof structure, the existingsituation was similarly prescriptive as the number and spacing of the columnshad to follow those of the construction of the historic upper tier of spectatorstands. The eighty axes of the existing building correspond directly with theeighty columns of the new roof construction. The looped cable roof employs aninner tension ring and two outer compression rings arranged on above another,between which the bearing cables are spanned like the spokes of a bicyclewheel. The floor plan of the stadium is determined by the running track withlong straight sides and semi-circular narrow sides, an arrangement that is notideal for the compression and tension ring system. As a result, the bentportion of the columns above the elbow half-way up incline only slightly alongthe long sides and more distinctly around the ends, their tips describing anelliptical form in plan in turn creating more curvature. The resulting geometrybenefits the building as a whole, lending it greater tension and character.
© gmp Architekten
© sbp/Marcus Bredt
© sbp/Marcus Bredt
建築師：gmp- Von gerkan Mark und partner
業主方：Nationalenterprise Olympic NSC
結構形式：輪輻式工作原理的環索屋蓋
長度：306m 寬度：236m
高度：65m 座位：68,000個
竣工時間：2011年5月
加拿大卑詩省體育館在1981年到1983年間建造完成並於1983年6月19日正式開放。其開始建造時是為了用作不列顛哥倫比亞雄獅隊和溫哥華白帽隊的主場。建成時這座體育場的屋蓋結構為氣承式膜結構穹頂，在當時該穹頂屋蓋是世界上最大的之一。該穹頂結構屋蓋在2010年和2011年間的翻新工程中被環索屋蓋結構替代。
BC Place was built between 1981 and 1983 and opened onthe 19th of June 1983. It had been built to serve as a home for the BC Lions ofthe Canadian Football League and the Vancouver Whitecaps, who then still playedin the North American Soccer League. Mostcharacteristic feature of the stadium back then was its air-supported domedroof, the world’s largest of its kind. It however got replaced during anextensive renovation which took place in 2010 and 2011.
考慮到現有的下部看臺結構以及業主希望翻新後的體育場成為溫哥華市區的一個地標的想法，輪輻式環索屋蓋結構的被選中做為了屋蓋的替換方案。對於卑詩省體育館的環索屋蓋結構，徑向鋼索向外連接於36根巨型的立柱，而這些立柱則沿著體育館外邊線設置於原結構之上。整個屋蓋結構由一個外壓環和一個內拉環組成，整個結構可以提供足夠的剛度以承受溫哥華地區200 kg/m²的雪荷載。在該屋蓋結構的內圈，還設置了另一個可開合式的膜結構屋頂，這個膜結構屋頂的開合用時約為10分鐘。屋蓋上鋪設的透光率較大的面積達9500 m²的ETFE膜對建築外觀及建築內部採光都有了很積極的影響。
Considering the structural performance of the existingstadium bowl and the desire for a landmark design in downtown Vancouver, alightweight cable-membrane structure has been chosen for the roof which worksaccording the spoked wheel principle. At the perimeter the cables are connectedto 36 iconic masts located on top of the existing structure. The system iscarefully balanced by an outside compression ring and an inner tension ringproviding sufficient stiffness to carry the immense snow loads of up to 200kg/m² in the Vancouver area. Besides the fixed membrane roof, the structureincludes a retractable roof consisting of inflatable membrane cushions whichunfold radially. The very transparent 9.500 m² ETFE perimeter facade has asignificant influence on the architectural appearance and the interior lightconditions.
© Michael Elkan
建築師： Stantec, Vancouver
業主方：BCPlace, Vancouver
合作單位：GeigerEngineers (engineer of record: David Campbell)
長度：261m 寬度：220m
固定屋蓋面積：32,500m2 可開合屋蓋面積：8,500m2
座位：56,000個
環索輕型屋蓋結構體系從第一次由sbp結構工程師設計研究並在大型體育場館中得以應用，到迄今在大多體育場館的屋蓋結構體系中得以不斷衍生發展，在解決大跨需要的前提下，可以在最大程度上實現場館內無柱空間和幾乎毫無遮擋的體育場內部視野。此外，由於大量採用了索、膜等材料，其結構效率，環保性和經濟性也具備極強的優勢，從工程界來推動社會向前進步，極具意義。
From the first time that the light-weight ring cableroof structure is developed and adopted in large stadiums to now that that itis broadly used in numerous of stadiums around the world, the ring cable roofstructure system is not only realizing the large span but also creating largenone-column space and the best view on site. Moreover, such a roof structuresystem possesses distinct advantage in terms of structural efficiency,economical efficiency and resource conservation. This is the way schlaich bergermannpartner is taking to make positive affect on human civilization progress.
在中國，sbp結構師事務所陸續在深圳寶安體育場、東莞體育中心、蘇州工業園區體育中心、海口五源河體育場等項目上均採用了基於輪輻結構原理的屋蓋結構。其中前三者作為閉合屋面要求的體育場，採用的是具備自錨特性的環索屋蓋結構體系；而對於海口五源河體育場，基於其月牙形的屋蓋形狀要求，我們將結構由自錨變換為屋蓋支座錨入下部結構。不同的項目，根據具體的邊界條件進行相應調整，可是，結構設計本身都應該是在基於充分理解結構原理的情況下進行的。正因為秉承這一原則，面對不同的項目背景，靈活的運用創新，才會使得環索輕型屋蓋結構在不同體育場館上以豐富多變的姿態展現給世人。
In China, schlaich bergermann partner has successfullypromoted such cable roof structure system following spoke-wheel principle insome stadium projects, such as bao』an stadium in Shenzhen, Dongguan sportscenter, SIP Sports Centre in Suzhou and wuyuanhe stadium in haikou. For thefirst 3 stadiums mentioned, we used self-anchored ring cable roof structuresystem as the shape of the roof is a closed loop. As for the wuyuanhe stadium,the self-anchored ring cable roof structure is not feasible as it is notpossible to build closed compression ring and tension ring on the crescentshape roof. The engineers in schlaich bergermann partner then developed anotherstructure. They decide to use semi-compression ring and semi-tension ring ofwhich both ends were anchored to the substructure. So the structure works inthe same principle of mechanics except for that the forces in the rings will goto the basement. Even if the same structural system is used, adjustments mustbe made as the boundary conditions of different projects must be different. Andall the adjustment should be based on the prerequisite that the structuralprinciple is fully understood by the designers. This is how engineers inschlaich bergermann partner are working and this is why the light-weight ringcable roof structure is developing rapidly and widely adopted in so manydifferent stadiums around the world.
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