A Retrospective View of Olympic Structures in China Tien T. Lan Institute of Building Structures, Chinese Academy of Building Research, Beijing 100013, China Received February, 26, 2008; Revised version April, 12, 2009; Acceptation May, 15, 2009 ABSTRACT: Sports facilities for Olympic Games and other events are constructed all over the world. These buildings require a larger and larger space for operation, which is characterized by long span, lightweight and variable forms. Various forms of spatial structures proved to be a rational and effective form to serve the purpose. In the paper, the modern developments of Olympic structures employing double layer grids, cable-suspended and membrane structures in China are reviewed. The illustrated examples show the impact of the advanced technique from outside and innovations on its own effort. In addition, three main structures for 2008 Beijing Olympic Games, i.e. the National Stadium, the National Aquatic Center and the National Indoor Stadium are discussed. It is expected that a large amount of construction on sports buildings for Olympic Games etc. will be done in China. Through Olympic structures, the interflow and cooperation between China and the world will further flourish in the future. Keywords: Spatial structures; Space frames; Cable-suspended structures; Membrane structures, Sports buildings. 1. INTRODUCTION A review of the development of the history of mankind reveals that one of its special features is the continuous improvement and expansion of its living space. From the remote antiquity, people dug into caves or built timber sheds, all these were only for the space of subsistence. With the development of science and technology, people learned to build more secure and comfortable spaces with different building materials. Not only living and production could be carried out in such space, but also various kinds of public activities. Consequently, construction of larger and larger spaces was required. From the Pantheon in ancient Rome to the modern Millennium Dome in London, the diameter of the dome increased from 43m to 320m. This shows the vivid example of the development of space for mankind. People will no more close the country to international intercourse, but to extend the exchange between countries, continents and to a worldwide scale. Such requirements will inevitably change the pattern of the construction. Among all kinds of activities for interchange, no doubt sport events are the most exciting one, which attracted thousands of people to attend. Consequently, sports facilities for Olympic Games and other events are constructed all over the world. Such buildings were employed not only in the sense of sports tournaments, but also expanded into to the scope of cultural, academic and commercial exchanges. For those buildings, the requirement of a large space for operation is characterized by long span, lightweight and variable forms. An overview of the development of these structures shows that three-dimensional spatial structures will most fulfill the above requirements. Various types of spatial structures, like shell structures, latticed steel structures, cable structures and membrane structures proved to be a rational and efficient form to serve the purpose [1]. International Journal of Space Structures Vol. 24 No. 2 2009 79 • Corresponding author. E-mail Address: [email protected]
Transcript
A Retrospective View ofOlympic Structures in China
Tien T. Lan
Institute of Building Structures, Chinese Academy of Building Research, Beijing 100013, China
Received February, 26, 2008; Revised version April, 12, 2009; Acceptation May, 15, 2009
ABSTRACT: Sports facilities for Olympic Games and other events areconstructed all over the world. These buildings require a larger and largerspace for operation, which is characterized by long span, lightweight andvariable forms. Various forms of spatial structures proved to be a rational andeffective form to serve the purpose. In the paper, the modern developments ofOlympic structures employing double layer grids, cable-suspended andmembrane structures in China are reviewed. The illustrated examples show theimpact of the advanced technique from outside and innovations on its owneffort. In addition, three main structures for 2008 Beijing Olympic Games, i.e.the National Stadium, the National Aquatic Center and the National IndoorStadium are discussed. It is expected that a large amount of construction onsports buildings for Olympic Games etc. will be done in China. ThroughOlympic structures, the interflow and cooperation between China and theworld will further flourish in the future.
Keywords: Spatial structures; Space frames; Cable-suspended structures;Membrane structures, Sports buildings.
1. INTRODUCTIONA review of the development of the history of mankindreveals that one of its special features is the continuousimprovement and expansion of its living space. Fromthe remote antiquity, people dug into caves or builttimber sheds, all these were only for the space ofsubsistence. With the development of science andtechnology, people learned to build more secure andcomfortable spaces with different building materials.Not only living and production could be carried out insuch space, but also various kinds of public activities.Consequently, construction of larger and larger spaceswas required. From the Pantheon in ancient Rome tothe modern Millennium Dome in London, thediameter of the dome increased from 43m to 320m.This shows the vivid example of the development ofspace for mankind.
People will no more close the country tointernational intercourse, but to extend the exchange
between countries, continents and to a worldwide scale.Such requirements will inevitably change the pattern ofthe construction. Among all kinds of activities forinterchange, no doubt sport events are the most excitingone, which attracted thousands of people to attend.Consequently, sports facilities for Olympic Games andother events are constructed all over the world. Suchbuildings were employed not only in the sense of sportstournaments, but also expanded into to the scope ofcultural, academic and commercial exchanges. Forthose buildings, the requirement of a large space foroperation is characterized by long span, lightweight andvariable forms. An overview of the development ofthese structures shows that three-dimensional spatialstructures will most fulfill the above requirements.Various types of spatial structures, like shell structures,latticed steel structures, cable structures and membranestructures proved to be a rational and efficient form toserve the purpose [1].
International Journal of Space Structures Vol. 24 No. 2 2009 79
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Figure 1. Double Layer Grids for Capital Sports Hall.
2. THE MODERN DEVELOPMENT2.1 An OverviewThe development of contemporary long span roofstructures in China was influenced by the technologyfrom the Western world. The application of spatialstructures could be said to have commenced in the earlyfifties, when different types of reinforced concrete shellswere built. The largest shell structure is an ellipticaldome, which has a clear span of 60m and covers amachinery shop. Since the mid sixties, a plate-likesystem of space frame – double or multiple layer grids,has been developed as one of the most proliferated typeof spatial structures. It has been chosen as the main typeof structural system for sports buildings as well as forhangars. The maintenance hangar in Beijing CapitalAirport has a double span of 153m with a width of 90m.Latticed shells were developed later by taking advantageof the mature technique from double layer grids. A hugelatticed shell composed of a braced barrel vault in thecentral part and two half-domes at both ends was builtfor the Ice Skating Rink in Harbin. The shell is quasi-elliptic in shape with an overall dimension of 86.2m ×191.2m. Braced barrel vaults supported along thelongitudinal edges were used extensively for the storageof bulk materials. The largest span is a coal storage forHuaneng Heat and Power Plant in Beijing, which coversa span of 120m and a length of 210m. Cable structureswere first used to cover long span sports buildings asearly as 1960. New types of cable roof were developed,such as the double layer counter-stressed cable systemand transversely stiffened single-curvature cable-suspended system. The concept of tension structure wasfurther extended to membrane roofs in 1970s. A kind ofnew synthetic material which can resist tensioneffectively opened a new era for membrane structures.One of the recent trends in the design of long span roofsin China is the innovation of hybrid structure. Somekinds of supporting structure, like arch, rigid frame orstayed cable are used in combination with certain typeof spatial structures. The great structural potential andvisual beauty of spatial structures have provided anideal solution for covering long span buildings [2].The following examples taken from the advances ofspatial structures in China show the impact ofadvanced technique from outside and innovations onits own effort.
2.2 Double Layer Grids for SportsBuildingsIn 1967, a new sports hall accommodating 10,000 seatswas planned to be built in Beijing. It was to be thelargest indoor stadium that has ever been built in China.Architects and engineers were facing the problem of
finding new structural forms to replace theconventional steel arch or truss. It happened that thePauley Sports Center for the University of California atLos Angeles covered with a 91m × 122m space framecame to the sight of designers. Inspired by the similarstadium in U.S., two-way diagonal latticed grids wereused to roof the Capital Sports Hall covering an area of99m × 112m (Fig. 1). Members were made ofcomposed angle sections to replace the rolled H-sections in Pauley Sports Center, and both wereconnected by high tensile bolts. The construction ofCapital Sports Hall proved that the space frame wasboth mature in technique and rational in cost. It couldmeet all functional requirements of long span roofs andcompete favorably with conventional systems. It wasso successful that almost all these large sports halls orgymnasiums in the major cities of China wereconstructed with double layer grids later [3]. InShanghai, it was further developed to suit the plans incircular and hexagonal shape. The Shanghai SportsArena is 110m in diameter (Fig. 2) and the ShanghaiNatatorium is an unsymmetrical hexagon with axesmeasuring 95m and 90m respectively. Three-waylatticed grids were used, which were interconnected bylatticed trusses in three directions. The members weremade of circular tube sections and connected bywelded hollow spherical nodes. Hence double layergrids were always chosen as the structural system forthose important sports events. For the 11th AsianGames held in Beijing, in 13 new sports buildings, 7gymnasiums employed double layer grids as the roofwith span ranging from 50m to 70m.
2.3 Cable-suspended Roofs for SportsBuildingsThe first attempt to build a long span cable-suspendedroof in China was in 1961. The Beijing Workers’ SportsHall used a circular double layer cable-suspended
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structure with a diameter of 94m. The bicycle- wheeltyped structure was constructed by adapting the fruitfulexperience from two former cable roofs built abroad –the US pavilion at Brussels World Exposition in 1958and the Utica Memorial Auditorium in 1960, withdiameters of 104m and 73m respectively. An ingeniousapproach was taken by incorporating a double set ofradial cables, upper and lower layer, connected to anouter compression ring and two tension rings at thecenter. Such arrangement not only produced a self-anchoring system, but also was vibration resistant.
In the early 1980s, a single curvature cable-suspended structure was used for the ZhiboGymnasium, Shandong Province, with a span of 54m(Fig. 3). However, such type of structure was inspiredby the Western practice, such as an exhibition hall inDortmund with 80m span and a natatorium inWuppertal with 65m span. Such form of hanging cableis vulnerable to wind and vibration effects and usuallywill induce instability of the cable. In earlier days,heavy dead load for the roof was used to solve thisproblem. It was further improved by using a method ofoverloading-prestressing process as has been done inMontevedio Stadium in Uruguay. In Zhibo, the cableswere prestressed by overloading on the roof, and thejoints between the roof slabs were filled with fineaggregate concrete. After removing the excess loading,the cables act integrally with the roof slabs like aconcrete shell, which provides sufficient flexuralrigidity to the roof surface.
Due to the shortcoming of excessive heavy deadload, the modern trend is to replace the concrete roofslab with light cladding like metal decks. In China,an innovative method of establishing transverselystiffened elements on the cables has been introduced.Cables are laid in one direction of the building, andthen trusses or beams are established orthogonally onthe cables. By depressing the end supports, the
trusses or beams become the stiffening elements, andpre-tensioning is resulted in the cables. The cablesand stiffening elements will act integrally, which willconsiderably increase the flexural rigidity of the roof.This system has been successfully employed inAnhui Gymnasium (Fig. 4), hexagonal in shape witha size of 72m × 69m, and also in YangpuGymnasium, Shanghai, 54m × 45m in rectangularshape. It was further developed into a doublecurvature saddle-shaped roof for ChaozhouGymnasium in 54m square [4].
2.4 Membrane Structure for SportsStadiumsMembrane structure, with the unique feature oflightweight and translucency, played an important rolein the field of spatial structures. The air-supportedmembrane structure of the U.S.A. Pavilion in OsakaExpo ’70 built in 1970 marked the beginning of the eraof membrane structure. Since then, it has developedrapidly on a worldwide scale. However, membranestructures were seldom used in China until 1997. Forthe 1997 China’s 8th National Games in Shanghai, a
new multi-functional grand stadium with a capacity of80,000 spectators was planned to be built. Membranestructure was employed for the cantilevered roof of themain stadium, covering an area of 36,100 m2. The roofis in elliptical form with a size of 288.4m × 274.4m,while the central open-air matching field is 213m ×150m (Fig. 5). The roof structure is composed of 32cantilevered steel trusses with spans that vary from 21mto 73.5m. Each truss is supported at the back into themain concrete superstructure columns. All cantileveredtrusses are interconnected and stabilized by three hooprings of steel space trusses to form a saddle shaped roof.A flying mast fabric roof structure is established on thecantilevered trusses. Each flying mast unit is built withfour upper ridges cables, four bottom suspension cablesand a flying vertical compression post. PTFE-coatedfiberglass was chosen to cover the roof.
It is worthwhile to mention that the originalconceptual design of this stadium employed acantilevered steel trussed system supporting atranslucent lightweight roof. Influenced by the trendsof those new stadiums around the world, the Chineseauthority concluded that a membrane structure wouldbe the best solution. In order to provide the mostadvanced new technology, material and construction,the U.S. engineers and contractors, WeidlingerAssociates and Birdair Inc., were invited to provide adesign-build service. However, it was too late to makea substantial change of the structural scheme and theoriginally proposed cantilevered steel trusses weremaintained. As the roof covering, a flying mast fabricroof structures was developed.
The construction of the membrane roof forShanghai Stadium had a profound and lastinginfluence on the development of membrane structuresin China. Since then, more than a dozen stadiums usedfabric to cover the canopies, each with an area of morethan ten thousand square meters [5]. Essentially the
structural system of Shanghai Stadium is a ‘FrameSupported Membrane Structure’, the main load-bearing structure is the steel trusses. It has evolved toa more complicated system of ‘Integral Pre-tensionedMembrane Structure’ where cables and the membraneact integrally. Such an example can be found in WeihaiStadium which is situated in Weihai city, ShangdongProvince, along the scenic east coast of China (Fig. 6).This stadium can accommodate 30,000 spectators. Thehorizontal projection of the canopy is in the shape ofquasi-elliptical, with an overall size of 236m × 209m,while the inner ring is 205m × 143m. The canopy roof,covering an area around 25,000m2, is composed of 34inter-connected umbrella shaped units with varyingsize. Each unit is constructed with ridge and valleycables covered with fabric and supported by a mastnear the center, inner ring in the front and boundarycable connected to the grandstand beam in the back.The inner ring is formed by a tensile cable which linksall units together. The size of each unit variesaccording to its position on the roof. The largest one isalong the shorter axis of the ellipse, with a cantileverspan of 33m, while the smallest one is along the longeraxis with 16m cantilever. The fabric used for thecanopy is PVC coated polyester with PVDF topcoating.
3. 2008 BEIJING OLYMPIC GAMES3.1 National StadiumThe new National Stadium is located in the center ofthe Olympic Green situated at the northern suburbanof Beijing. It will be the main site for the opening andclosing ceremony of the 2008 Olympic Games an alsofor the athletics and football matches. It is an 80,000seats capacity stadium, with an additional 11,000temporary seats for the Olympic Games. The structuralelements of the double-curved roof mutually supporteach other and converge into a grid-formation – like a
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Figure 5. Membrane Roof for Shanghai Stadium. Figure 6. Membrane Roof for Weihai Stadium.
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bird’s nest with its interwoven branches and twigs.This is what the architects, Herzog & De Meuron andChinese Architecture & Design Group, attempted toconceive (Fig. 7). According to the preliminary design,which is the winning scheme from an internationalselective tendering, this huge stadium is in quasi-elliptical shape, with major and minor axes of 332mand 296m respectively. In the central portion, there isa structural opening around the size of 140m × 70m –the inner bowl. A retractable roof is designed to coverthe inner bowl, so that the central portion of thestadium roof may be closed or open [6].
The primary structure for the roof is composed of aseries of steel portal frames rotated around the innerbowl. This arrangement provides a three dimensionalload-bearing system that distributes the largeconcentrated loads from the retractable roof evenly tothe perimeter. Each portal frame is formed by a megacolumn and 12m deep roof truss. The mega columnhas three main booms – one vertical and two inclined,they are tied together by diagonal elements forming athree dimensional truss system. The roof truss iscomposed of top and bottom booms made from 1.2m× 1.2m box sections with diagonal struts. Depth of thebottom chords reduces towards the center of thestadium from 1.2m to 0.8m. The boxes are weldedfrom steel plates with thickness varying from 15mm to60mm. The secondary structure, using similarstructural elements as the primary structure, dividesthe roof into different shapes of grids. Steel fabricationwill be complicated by the fact that some portal framesare intersected at very acute angles in the inner bowl.Likewise, at its edges the roof flows into smoothcorners, creating a seamless transition into the façade.Thus at the corner between façade and roof, the boxsections are curving and twisting in three dimensions.The steel fabrication and erection are by no means agreat challenge. Membrane panels are used to coverthe roof grids at the top and bottom booms level. A
single ply of ETFE foil with thickness of 0.25mmclads the roof surface. About 1500 panels withdifferent shapes fill in the grids formed by the primaryand secondary structures, totaling a developed area of40,000m2. An acoustic lining of PTFE fabric, also inthe form of panels, is established beneath.
Much controversy has been evoked on the structuralscheme of this main stadium. It is criticized that suchportal frame structure with flexural load-resistingbehavior is not suitable for use in long span roof ofmore than 300m. Although the structural engineer hasmade every effort to optimize the design, the effect ofreducing the steel consumption was very limited. Inorder to manage a thrifty Olympic Games, the designof the main stadium was reviewed and building costwas pared back. Following the advice of a group ofexperts, slimming down has taken place and the planlayout has been modified. The retractable roof iscancelled and the central opening above the field isenlarged to 190m × 124m. However, the concept of the‘nest’ is being maintained. Consequently, the totalsteel tonnage can be reduced from 53,875t to 41,875tand 12,000t of dead load is reduced from the roof.Despite this chopping, it is still enormously heavy. Theresult is an astonishing amount of steel consumption.
3.2 National Aquatic CenterThe National Aquatic Center is also located in thecenter of the Olympic Green in Beijing, opposite to theNational Stadium. It is the venue for themultifunctional aquatic sports for the 2008 Olympicswith a seating capacity of 11,000 plus 6000 temporaryseats. It will also serve as a sports and recreation centerfor the public [7]. This is a winning design of aninternational competition submitted by the uniteddesign group composed of China Construction(Shenzhen) Design International, PTW ArchitectsAustralia and Ove Arup Australia. The structural formof the building imitating the composition of water
Figure 7. Plan and Model of National Stadium.
bubbles was highly appreciated for its creativeness.The square sided cube seems to be extremely simple,but the variations are shown by cladding the walls androof by different shapes of air cushions. The patternlends itself with high repetition which is essential foreasy construction, yet it gives the impression oforganic irregularity (Fig. 8).
Inspired by water, the architectural design concept isto put water into a cube [H2O]3, this is where the nameof the building ‘Water Cube’ comes from. The entirebuilding is a cubic of 177m × 177m × 31m in size,totaling an area of 80,000m2. The constitution of thesteel roof and wall structure is originated from a cuttingmodel of a three dimensional space with maximumefficiency. In the early 1990s Irish professors Weaireand Phelan proposed a most reasonable scheme to fillin a space. The constitutive model is composed of twodifferent polygonal elements, one with 14 surfaces andthe other with 12 surfaces. The former polygonalelement has 2 hexagons and 12 pentagons, while thelatter element has all pentagons. The Weaire-Phelanscheme is considered to be the most efficientconstitution in a space. The geometrical configurationof the building is created on the basis of the abovemodel. An array of Weaire-Phelan polygons is firstformed with a size bigger than the building. Rotatingthe array about an axis, the polygons that fall eitheroutside the building envelope or within the inner space
are trimmed off. The resulting polygons form the roofand walls of the building. The boundary lines of thepolygonal elements on the trimming planes constitutethe top and bottom chords of the roof structure as wellas the chords of the interior and exterior surfaces of thewalls. At the same time, the edges of the polygonsbetween two trimming planes constitute the webmembers (Fig. 9).
Square or rectangular hollow sections are used forall chord members on both surfaces of the roof andwalls, either connected directly or by semi-sphericalnodes. Circular hollow sections are used for the webmembers inside and connected by spherical nodes. Theload-resisting behavior of these new types ofpolyhedron space grids is characterized by therelatively large bending moments at the ends of themember which requires rigidly connected joints. With3m thick walls and 7m deep roof, the claddings insideand out are made with ETFE air cushions. ETFE isabbreviated from Ethylene Tetra Fluoro Ethylenewhich is a kind of extruded foil. Its special featureslike lightweight, transparent and self-cleaningproperties become an ideal cladding material for theAquatic Center. The triple layer air cushions withthickness around 0.2 – 0.25mm are made according tothe shapes of the polygons, the largest panel being9m2. An air inflating system will keep constantpressure (from 200 to 750Pa) in the air cushions so
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Figure 8. National Aquatic Center.
Figure 9. Constitution of the Structure.
Tien T. Lan
that they can resist loadings. The total area of theETFE claddings amounts to 300,000m2.
3.3 National Indoor StadiumThe National Indoor Stadium is one of the three mainbuildings situated in the Olympic Green and serves forgymnastics and hand ball matches during the OlympicGames. Although there was a schematic designselected for this project, the final design wasaccomplished by the Beijing Institute ofArchitectural Design (Fig. 9). The entire building iscomposed of a competition area with 17400 seats anda warm-up area, totaling 80,890m2. The planeprojection of the roof is two rectangles. The one overthe competition area is in the size of 144.5m × 114mwhile the smaller one over the warm-up area is 63m× 51m, all with overhangings around the perimeters.The roof is in a wavy shape formed by concave andconvex cylindrical surfaces of different radii. [8]. Thearchitecture of this stadium is inspired by the“Chinese folding fan”. The nimble shape integratesaptly the function and tradition.
The roof structure of the indoor stadium employsa new type of two-way latticed grids with tensionedchords which is an evolution of “beam-stringstructures” in two directions. The two rectangularareas are all covered with orthogonally laid latticedtrusses at 8.5m intervals, with depth varying from1.52m to 3.97m. In the competition area with largerspan, additional elements composed of steel strutsand two-way tensioning chords are established underthe latticed grids. Circular hollow sections are usedfor all top chord and web members of the latticedgrids connected either directly or by hollowspherical nodes. Rectangular hollow sections areused for all bottom chord members connected bycast steel nodes. For tensioning chords beneath,cables made of cold drawn twisted steel wires with ahigh strength of 1670MPa are used. The construction
of the indoor stadium is complicated by the curvedconfiguration of the roof and different types ofconnecting nodes. In addition to the assembly of alarge number of members of the latticed grids, it isalso necessary to prestress the chord cables. Aninnovative method of sliding technique wasemployed.
4. CONCLUSIONOlympic structures are advancing rapidly all over theworld with the continuous emergence of newstructural types and new building materials. Theconstruction of long span roof structures and theapplied technique usually reflect the level of buildingtechnology of a country. The capability to build largescale sports facilities applying new structuralschemes and advanced technique will be animportant mark of the development of a nation’sscience and technology. Although China has made agreat progress in the field of long span spacestructures, there is still a lag behind the internationaladvanced level. The outgrowth of the rapiddevelopment of national economy in China is thelarge amount of construction on sports buildings forOlympic Games etc. For example, Beijing will behosting the 2008 Olympic Games; Guanzhou will behosting the 2010 Asian Games and Shenzhen for the2011 Universiade. A series of new sports facilities arenow under design or constructed [9]. It is interestedto see that many foreign design, consulting andconstruction firms are involved in it. The design andconstruction of these projects are usually executedthrough the mutual efforts of Chinese and foreignengineers. This will inevitably bring inspiring ideasand new technology to China. Through Olympicstructures, the interflow and cooperation betweenChina and the world will further flourish in thefuture.
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Figure 10. National Indoor Stadium.
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