C+A issue 02_jpeg braga.indd
Transcription
C+A issue 02_jpeg braga.indd
issue 02 Estadio Municipal de Braga Estadio Municipal de Braga Portugal 10 Eduardo Souto de Moura 11 issue 02 Estadio Municipal de Braga ≥ You can see the cables pulling and you can see the concrete working against the forces to transfer the load to the stone. The manmade structure is dependent on the natural rock for its stability and its makeup… it is this encounter, this meeting between the natural and the manmade that I find interesting to deal with. Eduardo Souto de Moura 12 13 issue 02 Estadio Municipal de Braga 1 Ticket office 2 Parking 3 Entrance square 4 Entrance gates 5 UEFA temporary parking 6 Alley 7 Water line 8 East square (lower level) 9 East stand 10 Trail 11 Field 12 West stand 13 West square (upper level) 14 Grass storage building 15 VIP parking 16 TV compound 14 15 issue 02 Estadio Municipal de Braga 16 When Portugal won the right to host Euro 2004, the 12th European soccer championships, the country set about an ambitious program of stadium building which, in a short period of time saw seven new stadiums built, while three were renovated, across eight cities at a cost of €550 million (AUD$896 million). All of the new facilities were designed by Portuguese architects and followed the form of traditional amphitheatre-style arenas you see in major cities around the world; save for one outstanding work: the Estadio Municipal de Braga designed by Eduardo Souto de Moura within the Dume Sports Park, on the northwest slope of Monte Castro overlooking the historic northern city of Braga. Shoehorned into a former stone quarry, Souto de Moura’s design for the 30,000-spectator stadium ignored the typology of the gladiatorial arena and re-envisaged it as two long stands of reinforced concrete with deep overlapping tiers running parallel to the pitch, with a 202 metre suspension coil cable concrete roof strung between the two stands, and no spectator stands behind each of the goals. At one end the goals are set almost hard against the rock face of the quarry, while at the other end the view is of countryside and the city of Braga below. This juxtaposition of the natural and man-made expresses the essence of the Braga Stadium and the result is a powerful piece of sports architecture that seems to have been carved out of the mountainside and quarry floor. The southwestern tribune in particular appears to grow literally from the craggy rock face as it climbs to a plaza at the top of the quarry; while the northeastern stand rises free from the quarry floor; leaning back, rhythmically articulated by 16 powerful inclined 50-metre-tall ribs of reinforced concrete, each just a mere one metre thick and designed to carry within them most of the stadium’s hydraulic and electrical infrastructures. In a geotechnical feat of massive proportions, 1.7 million cubic metres of granite and rock were blasted from the quarry face into which the south-western stand snuggles and crushed into aggregate for making the concrete for the structure of the stadium. The carving and shaping of the rock face was achieved through a series of small, precise blasts to shape a cleft in the walls of the quarry. A series of steel pins were then inserted into the rock wall to 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 underworld of intense darkness and light, descending from the plaza at the top of the quarry via stairs, lifts and concourses, with light drawn in through a series of vertical shafts. The southeastern stand is accessed from the quarry floor through stairs inserted between each of the vertical concrete piers; with longitudinal circulation achieved through a series of large circular openings cut into the concrete ribs to reduce overall mass. Its stability is ensured by reinforced concrete slabs supporting the stairs to each level. It is the subtle inverted arch of the suspended roof of the Braga Stadium, however, that is the highlight of Souto de Moura’s design. Spanning 202 metres over the playing pitch, pairs of full-locked coil cables, spaced 3.75 metres apart and strung between the two stands, support two massive independent slabs of reinforced concrete just 240mm thick, slipped over the cables 50 metres above the ground, to cover each stand of the stadium. The leading edges of each roof over the playing field are tied by steel gantries that carry lighting and sound. Rainwater is drained from the roofs by large steel spouts suspended from the concrete roof slabs and into 40-metre-long steel ‘aqueducts’ – of which 27 metres is cantilevered – anchored to 8-metre concrete columns in the southeastern embankment of the site. The water is channeled along a watercourse and stored for later use and distribution throughout the stadium complex. AFAssociados, the structural engineers for the stadium, describe the roof as a single curvature cable roof “relying on the self weight of the concrete elements to resist the effects of dynamic wind loads.” The behaviour of the roof was verified before construction in wind tunnel tests on both rigid and aero elastic models. Rui Furtado, a principal of AFAssociados, says the construction sequence of stress ribbon bridges and the Dulles Airport building in Washington, designed by Eero Saarinen, provided the firm with its direction for the roof, “using precast planks sliding over the cables with a thin layer of concrete poured on top to minimize problems arising from differential directions. “The reinforced concrete slab is 240mm thick and was determined by balancing the need for a stabilizing mass while minimizing the weight,” he says. “The prefabricated elements were assembled over the cables on top of the stands. Each new piece was linked to the previous piece with bolts and the pieces were slid along the cables on Teflon sliders.” When all the pieces were in position the transversal and longitudinal joints between the panels were cast in concrete. Souto de Moura talks of the roof in almost lyrical terms: “The cables carry great tension loads. They are tied to a battery of concrete pillars in the structure on either side of the field. These pillars lean outward against the pull of the cables. But that’s not enough. To counteract the thrust, the pillars are anchored to the stone they rest upon. So the roof is linked to the pillars which are linked to the stone. Ultimately it is the mountain that supports the roof. It is this encounter, this meeting between the natural and the manmade that I find interesting to deal with. You can see the cables pulling and you can see the concrete working against the forces to transfer the load to the stone. The manmade structure is dependent on the natural rock for its stability and its make-up. Thus having the stone wall of the mountain terminate the southeast end of the stadium instead of the usual seating is a fitting reminder that the stadium owes its existence to the mountain.” JR transversal section 17 roof plan 0 longitudinal section 10 20m issue 02 Estadio Municipal de Braga 18 19 issue 02 Estadio Municipal de Braga section 20 section Project statement The rock excavation and the roof were the big challenges for the design team. The roof had to be compatible with the idea of integrating the stadium and the environment. It was also to be as 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 Pavilion in Expo 98 (Alvaro Siza) came up as the natural solution. The rock existed to anchor the cables and the reaction of the roof in the cantilevered stand would help in stabilizing it. However, there were reservations in the uncertainty of the dynamic behaviour of a 202-metre-span roof and the fact that the roof would have to be built 50 metres high. The Portuguese Pavilion Roof has a 67.5 metre span and with a lower height was built with a total propping system from the ground. Research on similar structures and preliminary calculations showed the feasibility of the solution and that an appropriate geometry and slab weight could lead to a desirable balance of moments in the foundation for permanent load combinations. A structure of parallel ‘ribs’ would provide the required stiffness for the stand and would allow for all the stairs, concourses, bars, etc. to fit in between. Constructability was studied and a precast slab proved to be a feasible solution. Cost estimates revealed that it could fit within the budget. The design concept was then fixed and detail design began. The architect’s general approach is to allow the technical needs of the construction to rule the development of the design. Thus, outside of the definition of the spaces and the overall aesthetics, an intense, demanding and stimulating dialogue resulted between the architects and the engineers whereby the search for the design solutions only ended when both disciplines were satisfied. Clear and rigorous criteria were then agreed upon to mould the solutions to the technical needs of the building. The resulting solution had to be simple in form and in detail. But simplicity is only achieved through a gradual and continuous process of successive modifications that often bring up solutions that are quite different from the original ideas. The architects and engineers worked closely together to achieve a common goal, which was not viewed as the exclusive territory of one or the other. The concept was to build a set of suspension cables suspended from the beams at the top of the rib walls, supporting two independent concrete slabs that covered each stand. The geometry selected resulted from a compromise between the aim of the architect for an extremely subtle inverted arch and the value of the force produced on the structure by the horizontal component of the cable forces. The selection of the type of cable was also extremely important as it would influence the definition of the shape and technological characteristics of the roof. Two cable options were possible: full locked coil strand and parallel wire strand. After studying the different characteristics of the two solutions in terms of durability, anchoring devices and dimensioning, full locked coil cables were selected, which led to smaller diameters. In addition to standardizing the concrete slab height along the roof, the only significant modification from the initial project consisted of grouping the cables into pairs, with spacing between each pair of 3.75m, two times the initially planned 1.875m. To talk about the stadium’s structure is to talk about its architecture, and to explain its architecture is to tell the story of the engineering problems 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 in Structural Engineering International, Issue 2, 2005) northwest elevation – section section 21 issue 02 Estadio Municipal de Braga ≥ The cables carry great tension loads. They are tied to a battery of concrete pillars in the structure on either side of the field. These pillars lean outward against the pull of the cables. But that’s not enough. To counteract the thrust, the pillars are anchored to the stone they rest upon . So the roof is linked to the pillars which are linked to the stone. Ultimately it is the mountain that supports the roof. 22 Eduardo Souto de Moura 23 issue 02 Estadio Municipal de Braga 24 25 issue 02 Estadio Municipal de Braga level -2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 26 54 55 56 -2 Parking Technical gallery 1 Technical gallery 2 Technical gallery 3 Technical gallery 4 Technical gallery 5 Maintenance access Access 1 Access 2 Access 3 Access 4 Guard’s house Atrium Hall 1 Storage 1 Storage 2 Hall 2 Storage 3 Press conference room Regie Technical area Mix area VIP/UEFA’s corridor Journalists’ corridor VIP/UEFA’s elevator hall Journalists’ elevator hall Technical area 1 Technical area 2 UEFA’s corridor 1 UEFA’s corridor 2 UEFA’s work room 1 UEFA’s meeting room UEFA’s work room 2 UEFA’s storage UEFA’s office 1 UEFA’s office 2 UEFA’s office 3 UEFA’s office 4 Technical compartment 1 Medical centre’s corridor Medical centre Medical centre 2 Police Hall Cell 1 Cell 2 Cell 3 Electrical quarter Tranformation post Firemen Auditorium corridor Technical compartment’s corridor 2 Head of security’s corridor Staff/ball boys’ changing room Storage/catering Storage 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 Security resting room Security room Security kitchen Toilet 1 Toilet 2 Toilet 3 Toilet 4 Toilet 5 Toilet 6 Toilet 7 Toilet 8 Toilet 9 Toilet 10 Toilet 11 Emergency stairs Emergency stairs VIPs staircase Journalists’ staircase Staircase 1 Staircase 2 Staircase 5 Water tank access staircase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 0 Ramp Stair 1 Stair 2 Stair 3 Stair 4 Stair 5 Stair 6 Stair 7 Players atrium Field access Distribution corridor 1 Distribution corridor 2 VIP atrium Journalist atrium UEFA room Grass storage Lift access Distribution corridor Bar 1 Bar 2 Disabled toilet Toilet 1 Disabled toilet 2 Toilet 2 Electrical quarter access Electrical quarter 1 Toilet 3 Toilet 4 Electrical quarter access Electrical quarter 2 Toilet 5 Disabled toilet 3 Toilet 6 Disabled toilet 4 Toilet 7 Access to field entrance 1 Field entrance 1 Access to field entrance 2 Field entrance 2 Access to field entrance 3 Field entrance 3 Access to field entrance 4 Field entrance 4 Acess to field entrance 5 Field entrance 5 UEFA meeting room Field entrance 6 Access to field entrance 7 Field entrance 7 Access to field entrance 8 Field entrance 8 Access to field entrance 9 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 Field entrance 9 Access to field entrance 10 Field entrance 10 Access to field entrance 11 Field entrance 11 Access to field entrance 14 Field entrance 14 Access to field entrance 15 Field entrance 15 Access to field entrance 16 Field entrance 16 Bathroom 1 Technical area Bathroom 2 Hall Working facilities Electrical quarter Working facilities Working facilities Stair 8.2 Stair 9.3 Stair 9.4 Stair 10.3 Stair 10.4 Stair 11.3 (VIPs/UEFA) Technical area 2 Stair 12.3 (press) Stair 13.4 Stair 13.3 Stair 14.4 Stair 14.3 Stair 15.2 Stair 11.4 – VIP Stair 12.4 – press Stair 16.1 Stair 17.1 27 level -1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 -1 level 0 level 1 1 Public route Bar 1 Bar 2 Toilet 1 Toilet 2 Toilet 3 Toilet 4 Toilet 5 Toilet 6 First aid (waiting room 1) Reception 1 First aid toilet First aid (waiting room 2) Reception 2 First aid toilet Atrium VIP corridor Journalists’ corridor VIP elevator hall Jounalists’ elevator hall Technical area Electrical area Braga S.C. reception desk Braga S.C. room Braga S.C. storage room TV studio 1 TV studio 2 Deletates’ room Storage Games secretary room Resident team’s corridor 1 Male referecing Resident team’s coach room Resident team’s feet bathing area Resident team’s shoe store Social room 1 Social room 2 Social room 3 Visiting team corridor Female referecing Players medical centre 1 Visiting team feet bathing Visting team shoe store Resident team’s changing room access corridor 2 Visiting team corridor 2 Access atrium Hall Players medical centre 2 Anti-doping room 1 Anti-doping room 2 0 10 51 Laundry 52 Drying area 53 Resident team’s warm-up room 54 Resident team’s gymnasium 55 Resident team’s changing room access corridor 3 56 Patio 1 57 Resident team’s changing room 1 58 Resident team’s showers 1 59 Resident team’s scottish shower 60 Resident team’s whirlpool 61 Resident team 62 Resident taem’s WC 1 63 Resident team’s massage room 1 64 Resident team’s massage room 2 65 Resident team’s WC 2 66 Resident team’s showers 2 67 Resident team’s changing room 2 68 Visiting team’s warm-up room 69 Visiting team’s gymnasium 70 Visiting team’s changing room access corridor 3 71 Patio 2 72 Visiting team’s changing room 1 73 Visiting team’s showers 1 74 Visiting team’s scottish shower 75 Visting team’s whirlpool 76 Visiting team 77 Visiting team’s WC 1 78 Visiting team’s massage room 1 79 Visiting team’s massage room 2 80 Visiting team’s WC 2 81 Visiting team’s showers 1 82 Visiting team’s changing room 2 83 Toilet 1 84 Toilet 2 85 Toilet 3 86 Toilet 4 87 Toilet 5 88 Toilet 6 89 Toilet 7 90 Toilet 8 91 Toilet 9 92 Players emergency staircase 93 Players and staff emergency staircase 94 VIPs staircase 95 Press staircase 96 Public staircase 97 Public staircase 98 Public staircase 99 Public staircase 100 Public staircae 101 Public staircase 102 Emergency exit 103 Emergency exit 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 Ramp Stair 1 Stair 2 Stair 3 Stair 4 Stair 5 Stair 6 Stair 7 Elevators access Distribution corridor Cabin 1 Cabin 2 Cabin 3 Cabin 4 Cabin 5 Cabin 6 Cabin 7 Cabin 8 Cabin 9 Cabin 10 Cabin 11 Cabin 12 Cabin 13 Cabin 14 Toilet – male/female Cam 1 Cabin 15 Cabin 16 Cabin 17 Cabin18 Cabin 19 Cabin 20 Cabin 21 Cabin 22 Cabin 23 Cabin 24 Cabin 25 Cabin 26 Cabin 27 Cabin 28 Cabin 29 VIPs Restaurant Restaurant’s kitchen Storage Toilet 1 VIPs atrium Distribution corridor VIPs elevators access Technical Area 2 Press elevators access Technical area 1 Toilet 2 TV Studio access corridor TV Studio 1 TV Studio 2 TV Studio 3 TV studio 4 Bar kitchen Kitchen Storage Stair 9.2 Stair 10.2 Stair 11.2 – VIPs Stair 12.2 Stair 13.2 Stair 14.2 – TV studios 20m Project name Estadio Municipal de Braga Location Monte Crasto, Parque Norte, Braga Project January 2000 Construction January 2002 – December 2003 Architecture Souto Moura – Arquitectos, LDA Landscaping Daniel Monteiro Consultants Arup Associates – Dipesh Patel (Stadium Programme) Engineers AFAssociados – Projectos de Engenharia, SA Consultants CÊGÊ, 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, SA Photographer Christian Richters