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0 10 20m
transversalsection
roofplan
longitudinalsection
When Portugal won the right to host Euro 2004,the 12th
Europeansoccer championships,the country set about an ambitious
programof stadium building which,in a short period of time saw
sevennew stadiums built,while three were renovated,across eight
citiesat a cost of 550 million (AUD$896 million).All of the new
facilities were designed by Portuguese architectsand followed the
form of traditional amphitheatre-style arenasyou see in major
cities around the world;save for one outstandingwork:the Estadio
Municipal de Braga designed by Eduardo Soutode Moura within the
Dume Sports Park, on the northwest slopeof Monte Castro overlooking
the historic northern city of Braga.Shoehorned into a former stone
quarry,Souto de Mouras designfor the 30,000-spectator stadium
ignored the typology of thegladiatorial arena and re-envisaged it
as two long stands ofreinforced concrete with deep overlapping
tiers running parallelto the pitch,with a 202 metre suspension coil
cable concrete roofstrung between the two stands, and no spectator
stands behindeach of the goals.At one end the goals are set almost
hard againstthe rock face of the quarry,while at the other end the
view is ofcountryside and the city of Braga below.This
juxtaposition of the natural and man-made expresses theessence of
the Braga Stadium and the result is a powerful pieceof sports
architecture that seems to have been carved out ofthe mountainside
and quarry floor.The southwestern tribune in particular appears to
g row literallyfrom the craggy rock face as it climbs to a plaza at
the top of thequarry;while the northeastern stand rises free from
the quarryfloor;leaning back, rhythmically articulated by 16
powerful inclined50-metre-tall ribs of reinforced concrete,each
just a mere onemetre thick and designed to carry within them most
of thestadiums hydraulic and electrical infrastructures.In a
geotechnical feat of massive proportions,1.7 million cubicmetres of
granite and rock were blasted from the quarry face intowhich the
south-western stand snuggles and crushed intoaggregate for making
the concrete for the structure of the stadium.The carving and
shaping of the rock face was achieved througha series of
small,precise blasts to shape a cleft in the walls of thequarry. A
series of steel pins were then inserted into the rock wallto
stabilize the rock and prevent landslides.In the southwestern
stand,set barely a metre from the rock face,Souto de Moura has
created a dramatic Piranesian underworldof intense darkness and
light,descending from the plaza at thetop of the quarry via
stairs,lifts and concourses,with light drawnin through a series of
vertical shafts. The southeastern standis accessed from the quarry
floor through stairs inserted betweeneach of the vertical concrete
piers;with longitudinal circulationachieved through a series of
large circular openings cut intothe concrete ribs to reduce overall
mass.Its stability is ensuredby reinforced concrete slabs
supporting the stairs to each level.It is the subtle inverted arch
of the suspended roof of the BragaStadium,however,that is the
highlight of Souto de Mouras design.Spanning 202 metres over the
playing pitch,pairs of full-lockedcoil cables,spaced 3.75 metres
apart and strung between thetwo stands,support two massive
independent slabs of reinforcedconcrete just 240mm thick,slipped
over the cables 50 metresabove the ground,to cover each stand of
the stadium.The leadingedges of each roof over the playing field
are tied by steel gantriesthat carry lighting and sound.Rainwater
is drained from the roofs by large steel spoutssuspended from the
concrete roof slabs and into 40-metre-longsteel aqueducts of which
27 metres is cantilevered anchoredto 8-metre concrete columns in
the southeastern embankmentof the site.The water is channeled along
a watercourse and storedfor later use and distribution throughout
the stadium complex.AFAssociados,the structural engineers for the
stadium, describethe roof as a single curvature cable roof relying
on the self weightof the concrete elements to resist the effects of
dynamic windloads. The behaviour of the roof was verified before
constructionin wind tunnel tests on both rigid and aero elastic
models.Rui Furtado,a principal of AFAssociados,says the
constructionsequence of stress ribbon bridges and the Dulles
Airport buildingin Washington,designed by Eero Saarinen,provided
the firm withits direction for the roof, using precast planks
sliding over thecables with a thin layer of concrete poured on top
to minimizeproblems arising from differential directions.
The reinforced concrete slab is 240mm thick and was determinedby
balancing the need for a stabilizing mass while minimizingthe
weight, he says.The prefabricated elements were assembledover the
cables on top of the stands.Each new piece was linkedto the
previous piece with bolts and the pieces were slid alongthe cables
on Teflon sliders. When all the pieces were in positionthe
transversal and longitudinal joints between the panels werecast in
concrete.Souto de Moura talks of the roof in almost lyrical
terms:
The cables carry great tension loads.They are tied to a
batteryof concrete pillars in the structure on either side of the
field.These pillars lean outward against the pull of the cables.But
thatsnot enough.To counteract the thrust,the pillars are anchoredto
the stone they rest upon.So the roof is linked to the pillars
whichare linked to the stone.Ultimately it is the mountain that
supportsthe roof.It is this encounter,this meeting between the
naturaland the manmade that I find interesting to deal with.You can
seethe cables pulling and you can see the concrete working
againstthe forces to transfer the load to the stone.The manmade
structu reis dependent on the natural rock for its stability and
its make-up.Thus having the stone wall of the mountain terminate
the southeastend of the stadium instead of the usual seating is a
fitting reminderthat the stadium owes its existence to the
mountain. JR
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northwest elevationsection
Constructability was studied and a precast slab proved to bea
feasible solution.Cost estimates revealed that it could fit
withinthe budget.The design concept was then fixed and detail
designbegan.The architects general approach is to allow the
technicalneeds of the construction to rule the development of the
design.Thus,outside of the definition of the spaces and the
overallaesthetics,an intense,demanding and stimulating
dialogueresulted between the architects and the engineers wh ereby
thesearch for the design solutions only ended when both
disciplineswere satisfied.Clear and rigorous criteria were then
agreed upon to mouldthe solutions to the technical needs of the
building.The resultingsolution had to be simple in form and in
detail.But simplicityis only achieved through a gradual and
continuous processof successive modifications that often bring up
solutions that arequitedifferentfrom theoriginal
ideas.Thearchitectsand engineersworked closely together to achieve
a common goal,which wasnot viewed as the exclusive territory of one
or the other.The concept was to build a set of suspension cables
suspendedfrom the beams at the top of the rib walls, supporting
twoindependent concrete slabs that covered each stand.The geometry
selected resulted from a compromise betweenthe aim of the architect
for an extremely subtle inverted arch andthe value of the force
produced on the structure by the horizontalcomponent of the cable
forces.The selection of the type of cable was also extremely
importantas it would influence the definition of the shape and
technologicalcharacteristics of the roof.Two cable options were
possible:full locked coil strand and parallel wire strand. After
studyingthe different characteristics of the two solutions in terms
ofdurability,anchoring devices and dimensioning,full locked
coilcables were selected,which led to smaller diameters.In
additionto standardizing the concrete slab height along the
roof,theonly significant modification from the initial project
consistedof grouping the cables into pairs,with spacing between
eachpair of 3.75m,two times the initially plann ed
1.875m.Totalkaboutthe stadiumsstructureisto talkaboutits
architecture,andtoexplainitsarchitectureisto
tellthestoryoftheengineeringproblems it brought up and how they
were overcome.Rui Furtado,Carlos Quinaz,Renato
Bastos,AFAssociados,Gaia,Portugal
(This is an edited extract from an article published
inStructural Engineering International,Issue 2, 2005)
Project statementThe rock excavation and the roof were the big
challengesfor the design team.The roof had to be compatible with
the ideaof integrating the stadium and the environment.It was also
to beas light and clean as
possible.Therefore,arches,trusses,poles,cables and membranes were
eliminated as solutions.A suspended roof such as was used in the
Portuguese Pavilionin Expo 98 (Alvaro Siza) came up as the natural
solution.Therockexistedtoanchorthecablesandthereactionof theroofin
the cantilevered stand would help in stabilizing it. However,there
were reservations in the uncertainty of the dynamicbehaviour of a
202-metre-span roof and the fact that the roofwould have to be
built 50 metres high.The Portuguese PavilionRoof has a 67.5 metre
span and with a lower height was builtwith a total propping system
from the ground.Research on similar structures and preliminary
calcul ationsshowed the feasibility of the solution and that an
appropriategeometry and slab weight could lead to a desirable
balanceof moments in the foundation for permanent load
combinations.A structure of parallel ribswould provide the required
stiffnessfor the stand and would allow for all the
stairs,concourses,bars,etc.to fit in between.
section
section
section
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-21 Parking2 Technicalgallery13 Technicalgallery24
Technicalgallery35 Technicalgallery46 Technicalgallery57
Maintenanceaccess8 Access 19 Access 2
10 Access311 Access412 Guardshouse13 Atrium14 Hall115 Storage116
Storage217 Hall218 Storage319 Pressconferenceroom20 Regie21
Technicalarea22Mixarea23 VIP/UEFAscorridor24 Journalistscorridor25
VIP/UEFAselevatorhall26
Journalistselevatorhall27Technicalarea128Technicalarea229
UEFAscorridor 130 UEFAscorridor 231 UEFAsworkroom 132
UEFAsmeetingroom33UEFAsworkroom234UEFAsstorage35 UEFAsoffice 136
UEFAsoffice 237 UEFAsoffice 338 UEFAsoffice
439Technicalcompartment140 Medicalcentrescorridor41
Medicalcentre
42Medicalcentre243Police44 Hall45 Cell146 Cell247 Cell348
Electricalquarter49 Tranformationpost50 Firemen51
Auditoriumcorridor52 Technicalcompartments
corridor253Headofsecuritys
corridor54 Staff/ballboyschanging
room55 Storage/catering56Storage
57Securityrestingroom58Securityroom59 Securitykitchen60Toilet161
Toilet262Toilet363Toilet464Toilet565Toilet666
Toilet767Toilet868Toilet969Toilet1070 Toilet1171 Emergencystairs72
Emergencystairs73 VIPsstaircase74 Journalistsstaircase75
Staircase176 Staircase277 Staircase578 Watertank access
staircase
01 R a m p2 S t a i r 13 S t a i r 24 S t a i r 35 S t a i r 46
S t a i r 57 S t a i r 68 S t a i r 79 Playersatrium
10 Fieldaccess11 Distributioncorridor 112 Distributioncorridor
213 VIPatrium14 Journalistatrium15 UEFAroom16 Grassstorage17
Liftaccess18 Distributioncorridor19 Bar120 Bar221 Disabledtoilet22
Toilet123Disabledtoilet224Toilet225
Electricalquarteraccess26Electricalquarter127Toilet328Toilet429
Electricalquarteraccess30Electricalquarter231
Toilet532Disabledtoilet333
Toilet634Disabledtoilet435Toilet736Accesstofieldentrance137Fieldentrance138Accesstofieldentrance239Fieldentrance240Accesstofieldentrance341
Fieldentrance3
42Accesstofieldentrance443Fieldentrance444 Acessto
fieldentrance545Fieldentrance546UEFAmeetingroom47Fieldentrance648Accesstofieldentrance749Fieldentrance750Accesstofieldentrance851
Fieldentrance852Accesstofieldentrance9
53Fieldentrance954Accesstofieldentrance1055Fieldentrance1056Accesstofieldentrance1157Fieldentrance1158Accesstofieldentrance1459Fieldentrance1460Accesstofieldentrance1561
Fieldentrance1562Accesstofieldentrance1663Fieldentrance1664Bathroom165
Technicalarea66Bathroom267Hall68 Workingfacilities69
Electricalquarter70 Workingfacilities71 Workingfacilities72
Stair8.273 Stair9.374 Stair9.475 Stair10.376 Stair10.477
Stair11.3(VIPs/UEFA)78 Technicalarea279
Stair12.3(press)80Stair13.481
Stair13.382Stair14.483Stair14.384Stair15.285Stair11.4VIP86Stair12.4press87Stair16.188
Stair17.1
level -2 level 0
level1
Project name Estadio Municipal de BragaLocation Monte
Crasto,Parque Norte,BragaProject January 2000Construction January
2002 December 2003Architecture Souto Moura
Arquitectos,LDALandscaping Daniel MonteiroConsultants Arup
Associates Dipesh Patel(Stadium Programme)Engineers AFAssociados
Projectos de Engenharia,SAConsultants CG, Geotechnics;ARUP
Associates,Wind study;RWDI, rigid model wind tests;Danish Maritim
Institut,aeroelastic model wind tests),FEUP Construction
Institute,Dynamics.Construction Ace Assoc/Soares da
Costa,SAPhotographer Christian Richters
-11Publicroute2 B a r 13 B a r 24 Toilet15 Toilet26 Toilet37
Toilet48 Toilet59 Toilet6
10 Firstaid (waitingroom1)11 Reception1
12 Firstaidtoilet13 Firstaid (waitingroom2)14 Reception215
Firstaidtoilet16 Atrium17 VIPcorridor18 Journalistscorridor19
VIPelevatorhall20Jounalistselevator hall21
Technicalarea22Electrical area23Braga
S.C.receptiondesk24BragaS.C.room25Braga
S.C.storageroom26TVstudio127TVstudio228 Deletatesroom29Storage30G
amessecretaryroom31 Residentteamscorridor 132Male
referecing33Resident teamscoach
room34Resident teamsfeet
bathing area35Resident teamsshoe
store36Socialroom137Socialroom238Socialroom339 Visiting
teamcorridor40Female referecing41 Playersmedicalcentre 142Visiting
teamfeetbathing43Vistingteamshoestore44 Residentteamschanging
roomaccess corridor245 Visiting teamcorridor246Accessatrium47
Hall48Playersmedicalcentre249Anti-dopingroom150Anti-dopingroom2
51Laundry52Dryingarea53Resident teamswarm-up
room54Resident teams
gymnasium55Resident teamschanging
roomaccess corridor356Patio157Resident teamschanging
room 1
58Resident teamsshowers159Resident teamsscottishshower
60Resident teamswhirlpool61Resident
team62ResidenttaemsWC163Resident teamsmassage
room 164Resident teamsmassage
room 265ResidentteamsWC266Resident teamsshowers267Resident
teamschanging
room 268Visiting teamswarm-up
room69Visiting teamsgymnasium70Visiting teamschanging
roomaccess corridor371 Patio272 Visitingteamschanging
room 173 Visitingteamsshowers 174 Visitingteamsscottish
shower75 Vistingteamswhirlpool76 Visitingteam77 VisitingteamsWC
178 Visitingteamsmassage
room 179 Visitingteamsmassage
room 280VisitingteamsWC281 Visitingteamsshowers 182Visiting
teamschanging
room 283Toilet184Toilet285Toilet386Toilet487Toilet588
Toilet689Toilet790Toilet8
91Toilet992Players emergency
staircase93 Players andstaff
emergencystaircase94 VIPsstaircase95Press staircase96Public
staircase97Public staircase98Public staircase99Public staircase
100Public staircae101Public staircase102 Emergencyexit103
Emergencyexit
11Ramp2Stair13Stair24Stair35Stair46Stair57Stair68Stair79Elevators
access
10 Distributioncorridor11 Cabin1
12 Cabin213 Cabin314 Cabin415 Cabin516 Cabin617 Cabin718
Cabin819 Cabin920Cabin1021
Cabin1122Cabin1223Cabin1324Cabin1425Toilet
male/female26Cam127Cabin1528Cabin1629Cabin1730Cabin1831
Cabin1932Cabin2033Cabin2134Cabin2235Cabin2336Cabin2437Cabin2538Cabin2639Cabin2740Cabin2841
Cabin2942VIPs Restaurant43 Restaurantskitchen44 Storage45Toilet146
VIPsatrium47 Distributioncorridor48VIPs
elevatorsaccess49TechnicalArea250Press elevatorsaccess51
Technicalarea152Toilet253 TVStudio access
corridor54TVStudio155TVStudio256TVStudio357TVstudio458Barkitchen59
Kitchen60Storage61
Stair9.262Stair10.263Stair11.2VIPs64Stair12.265Stair13.266Stair14.2TVstudios
level-1
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