Architects:
POPULOUS, Boogertman Urban Edge + Partners
Structural Engineers:
P.D.Naidoo &Associates (PDNA) + Schlaich Bergermann &
Partners (Roof Consultant)
Project Architect:
Damon Lavelle (Principal, Populous), Bob van Bebber (BUEP),
Piet Boer (BUEP)
Il progetto si ispira alla “zucca” africana, nota come calabash, la cui estetica si apprezza maggiormente durante la notte.
Lo stadio si trova a sud-ovest di Johannesburg, vicino ad una delle aree più ricche di appassionati di calcio di tutta la regione, Soweto, dove vive circa il 40% della popolazione di Johannesburg. Il Soccer City Stadium può essere considerato la cattedrale del calcio sudafricano. Fu creato nel 1980 grazie ai leader di diverse squadre di calcio del Sudafrica che unirono le forze per finanziare la costruzione del primo stadio di calcio internazionale del paese che, nel 1990, ha anche ospitato il primo discorso pubblico di Nelson Mandela dopo la sua liberazione.
La capacità iniziale dello stadio, conosciuto come FNB, era di 80.000 spettatori, a fronte degli attuali 94.700 posti a sedere raggiunti con la ristrutturazione che ha comportato l’uso di 80.000 metri cubi di calcestruzzo, 9000 tonnellate di acciaio per cemento armato e 8000 tonnellate di acciaio strutturale oltre allo spostamento di circa 120 000 metri cubi di terreno.
L’involucro della facciata è costituito da pannelli in calcestruzzo fibrorinforzato, in una selezione di otto colori e due textures che fanno riferimento alla tonalità e alle texture della calabash.
L’involucro esterno è punteggiato da pannelli vetrati o aperti che costituiscono il motivo della facciata e che sembrano sparire quando i volumi sono illuminate all'interno. La facciata è articolata in 10 fasce verticali, geograficamente allineate con gli altri 9 stadi dei mondiali 2010 e con lo stadio di Berlino, sede della finale dei Mondiali 2006, il tutto a rappresentare la strada verso la finale di questa edizione.
La copertura superiore, a sbalzo da un enorme traliccio spaziale circolare, sostenuto da dodici colonne ci cemento alte 40 metri, è rivestita da una membrana in PTFE in un colore simile a quello della sabbia dei giacimenti di oro sudafricani.
Il Soccer City Stadium è stato premiato come overall building, per l’ampio uso di prodotti di cemento, per la complessità degli elementi strutturali e per la qualità estetica delle finiture. Ha, inoltre, vinto il premio Concrete in Architecture, per la sua forma, innovativa e culturalmente identificabile attraverso la ‘zucca’, che produce un’immagine realistica dell'Africa agli occhi del mondo.
PROJECT DESCRIPTION
By 2010, 80 000 cubic metres of concrete will have been poured, 9000 tons of reinforcing steel would have been placed and 8000 tons of structural steel will have been erected. This, in combination with the moving of approximately 120 000 cubic metres of soil, fine architecture and dedicated efforts in the design offices and on site, will result in Soccer City being transformed into one of the most striking, impressive and well-equipped stadiums in the world. The ±90 000 seater venue will host both the opening match and the final of the 2010 FIFA World Cup.
The existing structural concrete profile of the two suite levels and upper tier were extended all round to encircle the pitch. The existing lower embankment was rebuilt in insitu off-shutter concrete to vastly improve the view lines and comfort of the most popular seats in the house. The upper third of the existing embankment was raised to form a secondary tier on new concrete rakers and pre-cast concrete steppings. The upper embankment and the rebuilt lower embankment are accessible from the lower concourse, which is fed from the podium level. The two suite levels and the upper tier are accessed via 3-dimensional concrete ramp structures that are contained within the façade of the pot. The suite levels also have separate lift and stair lobbies at each corner for secure VIP access.
The pot’s façade is made up of fibre reinforced concrete panels, in a selection of 8 colours and 2 textures that reference the shades and textures of the calabash. The pot is punctured by open or glazed panels that suggest pattern on the façade, which comes into its own when the inside volumes are illuminated. The façade is articulated by 10 vertical slots which are aligned geographically with the 9 other 2010 stadia as well as the Berlin stadium. They are -representative of the road to the final. The calabash façade is supported by inclined off shutter 3 dimensional curved concrete columns which have a horizontal eccentricity of 6.5m in relation to its base.
The upper roof, which is cantilevered from an enormous triangular spatial ring truss, is covered by a PTFE membrane in a colour similar to that of mine-dump sand. The bottom of the trusses is covered by a perforated mesh membrane, thus giving the appearance of a smooth under-slung ceiling. The triangular spatial ring truss is supported by twelve, 40 meter high concrete shafts which are subjected to huge tension and compressive forces and consequently have piles which are anchored in the bedrock.
The choice of concrete for the bulk of the structure was taken to match with the existing structural profile so as to enable all pre-cast units to be made on site, and to improve on the costs and lead times of a structural steel framework.
THE SITE
The site is directly north of the new Nasrec Transportation Hub and pedestrian promenade, linking the stadium to the redeveloped Johannesburg Expo Centre to the south. The transportation hub accommodates taxi, bus, and rapid transit services, thus providing good public transport links to the precinct and the stadium. A secondary Bus Rapid Transit station is under construction on the Soweto highway to the north of the stadium, which will further strengthen the public transport links to the stadium. All of this is set in a revamped Nasrec Arena precinct, which will boast new roads, and pedestrian walkways with lighting, signage, landscaping, CCTV, and public amenities.
ARCHITECTURAL DESIGN DESCRIPTION
The architectural design of the stadium was selected from a series of concept designs, ranging from an acknowledgement of Jo’burg’s disappearing mine dumps; the kgotla (defined by the tree) of the African city state; the African map as a horizontal representation, which included the roof as a desert plane supported on tropical trees set within the mineral wealth of Southern African; to a representation of the protea, our national flower.
The calabash, or African pot design was selected as being the most recognisable object to represent what would automatically be associated with the African continent and not any other. The calabash, or ‘melting pot of African cultures’, sits on a raised podium, on top of which is located a ‘pit of fire’. Thus the pot sits in a depression, which is the ‘pit of fire’, as if it were being naturally fired. The pit of fire demarcates the security and turnstile line separating the outer areas and the secure inner areas.
The structural profile of the existing suite levels and upper-tier seating of the existing western grandstand were extended all round to encircle the pitch. The existing lower embankments were rebuilt to vastly improve the view lines and comfort of the most popular seats in the house. The upper third of the existing embankment was raised to form a secondary tier, thus turning the stadium into a 3-tiered, rather than a 2-tiered, stadium. The upper embankment and the rebuilt lower embankment are accessible from the lower concourse, which is fed from the podium level. The two suite levels and the upper tier are accessed via 3-dimensional ramp structures that are contained within the façade of the pot. The suite levels also have separate lift and stair lobbies at each corner for dedicated secure VIP access.
The pot’s façade is made up of laminated fibre reinforced concrete panels, in a selection of 8 colours and 2 textures that make reference to the shades and textures of the calabash. The pot is punctured by open or glazed panels which create a suggestion of pattern on the façade that comes into its own when the inside volumes are illuminated. The façade is articulated by 10 vertical slots which are aligned geographically with the 9 other 2010 stadia, as well as the Berlin stadium. These are representative of the road to the final, and it is hoped that, after the World Cup, the scores of each game at each venue will be placed in pre-cast concrete panels on the podium. A visit to the stadium will thus provide one with a full history of the World Cup and all its scores.
The upper roof, which is cantilevered from an enormous triangular spatial ring truss, is covered by a PTFE membrane in a colour similar to that of the adjacent mine-dump sand. The bottom of the trusses will be covered by a perforated mesh membrane, thus giving the appearance of a smooth under-slung ceiling.
All VIP areas and the stadium management offices will be located behind the main western grandstand, with a dedicated VIP entrance. New change rooms, media work areas, auditorium, and VIP parking are located within a new basement under the podium on the western side of the stadium.
ARCHITECTURAL DESIGN TEAM
Notwithstanding the numerous architects, technicians and specialists involved in the Soccer City project the principal design team are:
Damon Lavelle - Principal: Populous
Bob van Bebber – Project Director: Boogertman Urban Edge + Partners
Piet Boer – Senior Associate & Project Architect: Boogertman Urban Edge + Partners
STRUCTURAL DESIGN
P.D. Naidoo & Associates (PDNA) are the principal structural engineers for the upgrading of Soccer City. PDNA appointed a German company, Schlaich Bergermann & Partners, as a specialist roof sub-consultant to assist with the detail analysis and design of the roof and façade structures.
The existing stadium, which was first constructed in 1987, consisted of a playing field surrounded by embankment seating, 2 levels of corporate hospitality suites, and an elevated seating tier on the western side only.
The architects for this prestigious project Populous, in partnership with , Boogertman Urban Edge + Partners,have created, an “African Pot” which will in future be recognized instantly by spectators in every corner of the world. To achieve this unique look, a structure, circular in shape on plan, was created to envelope the upgraded triple-tiered concrete seating bowl.
The circular plan format of the pot, which encircles the rectangular seating bowl and field, was selected to ensure that all façade detailing could be consistent in plan and section, thus ensuring an easier detailing, manufacture, and installation process. This furthermore ensured that the 120 concrete façade columns would be consistent in shape and form. Given that the existing concrete structure was limited in its ability to carry the additional roof load imposed on it, it was decided by the design team to remove the roof structure from the seating bowl structure and place the roof structure on 12 off-shutter concrete shafts. These shafts required an ingenious piling solution.
Piling
Approximately 1350 piles have been installed at Soccer City. The forces generated by the concrete structure and roof mean that exceptionally high loads are transferred to the foundations, which resulted in the design and construction of some of the most extreme piles ever installed in South Africa. All the piles and lateral support were designed by ARQ and Verdicon, and installed by GEL.
Whilst many of the piles carry large compressive loads, many piles are also subjected to exceptionally high tension loads. The calabash-shaped façade and the roof transfer the loads from the roof, down twelve reinforced concrete shafts and 120 inclined perimeter façade columns, to the piled foundations. Some shaft foundations are required to resist tension loads up to 13000kN, in combination with sheer loads of 6000kN and a bending moment of 125000kNm. Due to the limited space, it was only possible to install a maximum of 12 piles per shaft foundation, resulting in some piles being subjected to tension loads of 5800kN (580 tons). In order to accommodate the massive loads, the designers decided to anchor the piles 6m into the sandstone bedrock using dowel bars installed through the base of the pile.
In some cases the 1500 diameter piles were installed up to a depth of 33m, necessitating almost 60m³ of concrete in a single pile.
Shafts
The roof is supported by 12 large, 40m-high rectangular concrete shafts, each of which is designed to withstand large horizontal and vertical loads. The shafts vary in plan from 3.5m x 5.0m to 3.5m x 14.0m, with an average wall thickness of 600mm. A huge reinforcing steel content of 460kg/m³ (approximately three times more than normal reinforced concrete) made the placing and compaction of the concrete extremely difficult. The stiffness of the shafts under varying load combinations had to be determined accurately, as this affected the forces in the structural steel roof structure. The design and stiffness of the shafts was further complicated by various openings which had to be provided for electrical, mechanical, fire, domestic, and storm water services.
All these services were designed early on in the process and modelled in 3D by the architects to ensure that all penetrations were fully co-ordinated, before the reinforcing was designed by the engineers. This was required as it was impossible to entertain any late requests for penetrations by the services engineers. These shafts are founded on the piled foundations described above, with some piles subjected to downward loads of 1100 tons and upward loads of 580 tons. In addition to the shafts, 16 circular columns of 1 meter diameter support the roof.
Shaft bases
In order to transfer the large loads from the roof, via the concrete shafts, into the tension and compression piles, large pile caps with depths in excess of 4m were required. The construction of these large bases required careful planning, as heat of hydration had to be controlled, and the safety of construction workers, who were often required to work beneath heavy reinforcement, had to be ensured. Varying soil conditions on site often required that the engineers had to adapt the design of these bases.
Lateral Support
To allow access into the completed stadium bowl, three deep tunnels had to be cut with vertical excavation. The western players’ tunnel runs below the existing stadium structure, and has permanent support with a maximum vertical height of up to 10.0m.
The south-west and north-east tunnels have been constructed through new portions of the stadium. Due to programming constraints, it was decided to construct permanent lateral support in these tunnels, consisting of soil nails, shotcrete, and mesh. Due to the construction of deep pile caps at the base of the north eastern tunnel, vertical lateral support heights of up to 13.0m have been constructed.
Raking Beams
In order to vastly improve the sightlines of the existing stadium, the rake of the existing western upper tier has been increased, and an additional raised seating tier has been introduced on the upper portion of the embankment. Two levels of hospitality suites and the upper tier have been completed on the northern, eastern, and southern pavilions, thereby creating a classic triple–tiered bowl. All raking beams were constructed using purpose-made formwork. The existing pre-cast steppings to the western upper tier were removed, crushed, and recycled as base layers for the bulk earthworks. All new seating steppings are constructed from pre-cast concrete, all made on site.
Pre-Cast yard and pre-cast elements
To reduce the handling time and damage to precast units, as well as to achieve a value-for- money product, GLTA/Interbeton elected to establish an on-site batching plant and pre-cast yard. This allowed for easy inspection and control of the units, which were all unique in dimension due the existing geometry of the old stadium bowl, allowing them to be placed correctly with the minimum amount of handling.
Façade Columns
One of the most challenging elements of the concrete structure was the design and construction of the façade columns. The façade structure is supported on 120 inclined concrete columns enveloping the stadium. The columns are 16.3m high, and the top of each of these columns has a horizontal eccentricity of 6.5 metres in relation to its base, resulting in large moments and upward loads on the piled foundations. Due to the large moments and forces in these slender columns, the reinforcing steel is extremely dense (860 kg/m³), which made the use of a vibration poker extremely difficult. GLTA/Interbeton opted to use self-compacting concrete to construct these columns. All façade columns are connected with tie beams which act in ring tension so as to limit long-term deflection of the columns and façade structure. The design and construction of the façade columns was planned and executed very carefully, with temporary propping and bracing, so as to prevent deflection during construction.
Façade cladding
The final selection of the façade material came about after an extensive search by the architects to select a product that would ultimately reflect the nature of the concept of the calabash. Having discarded ideas of composite aluminium, steel, and various roof-sheeting options, the architects were coincidently introduced to an extruded fibre reinforced concrete panel called Fibre C, from Rieder Elements in Austria.
The product was supplied in panels with varying surface finishes, honed and sandblasted, in combination with a variety of earthy colours, to create the unique variegated façade cladding. The panels, which are light-weight and only 13mm in thickness, were supplied in 1200 x 1800mm typical panel sizes and were fixed to a galvanised steel sub frame. The panels, furthermore, have excellent thermal properties and have been subjected to rigorous testing, including hail impact, water penetration, and discolouration tests.
Ramps
Eight large pedestrian ramps, designed for the efficient ingress and egress of spectators to the upper levels of the stadium, have been provided. These ramps, which also provide vehicular access to all levels, follow the shape of the façade bowl and consequently change position in plan from one level to the next. In addition to the sloped façade columns, the other columns supporting the ramps are inclined and required intricate design analysis and construction techniques.
MECHANICAL SERVICES INSTALLATIONS - SYSTEMS DESCRIPTIONS
As prepared by: IZAZI CONSULTING ENGINEERS (PTY) LTD
Introduction:
Izazi Consulting Engineers were appointed to provide Professional Services in respect of the design and contract supervision of mechanical installations to the upgrade of Soccer City Stadium, Nasrec.
Services included the following:
•Domestic water installation inside the stadium, including water pumping systems
•Drainage installation inside the stadium
•Fire protection water service inside the stadium
•Automatic sprinkler fire protection installation
•Fire alarm installation
•Vertical transportation installation
The following briefly describes the systems designed, and highlights innovative design aspects of the installations.
Description of the Systems:
Domestic Water Installation.
The domestic water supply to the stadium consists of two components, namely a potable water system to supply to basins, sinks, showers, etc., and a separate water supply system serving only flush valves on toilets.
Water is stored in two separate storage tanks, located at basement level, and each with a usable capacity of approximately 600 cubic meters. One tank is filled from the municipal water supply, (potable supply) and the other is filled with rain water run-off from the interior of the stadium, harvested and stored in the original moat which surrounded the original playing field. This moat, which was constructed to prevent spectators from reaching the field , is not required anymore and was covered with a concrete slab resulting in a water storage facility of approximately three thousand cubic metres.
In times of plentiful rain fall, water is pumped from the moat to the basement storage tank to serve the toilets, maintaining a minimum supply of rain water in the moat for irrigation of the playing field. The pumps used for this also double as playing field irrigation water supply pumps. In times of limited rain fall, municipal water is used to irrigate the playing field, and also to fill the water tank feeding the toilets. Control of the system is automatic, based on water levels sensed at various locations.
The main water pump system consists of two sets of pumps: one with four pumps providing potable water to fittings, and another of three pumps serving the toilets. The toilet supply pumps also double as external irrigation system supply pumps, as the irrigation system does not run when demand exists for the toilet pumps. All the pumps are speed controlled, such as to only supply the water flow required by the instantaneous demand. This ensures minimum power consumption whilst still providing the required flow rate.
Water is distributed via two separate pipe reticulations, which are provided in the form of ring mains surrounding the stadium with regular vertical branches to the different levels.
The pump system design is such that, in the event of pump failure, municipal water supply automatically bypasses the tanks, and feeds directly into the water reticulation systems.
In addition to the main booster pump systems, four booster pumps have been provided at upper Concourse Level, to boost the water pressure to four piped roof wash-down systems, located at the main gutter on the field side of the stadium roof. These systems each consist of a number of hose connection points, to be utilized for the regular wash down of the translucent sections of the stadium roof. Pump operation is pressure switch controlled.
Water supply pipe materials are galvanized steel pipes with grooved fittings for larger diameters, and composite material pipe with crimped fittings for smaller diameters (50mm diameter and less), and all hot water circulating systems. This combination was found to be the most economical, whilst still ensuring long life of the systems. Pilfering of pipes during construction, which is a common problem with copper pipe work, was also non -existent on this project.
Domestic hot water is generated by means of nine separate systems: eight of which are in plant rooms located in four quadrants of the stadium at Hospitality Suite Level, and one at basement level. The former supply hot water to the Hospitality Suites via circulating mains, and the Basement system serves the basement change rooms and main kitchen. Water is heated by means of low power in line electrical heaters and stored in tanks with large hot water storage capacity.
In view of the large number of toilets on the site, (approximately 1 100) with peak use over short periods during breaks in events, pipe sizes had to be carefully designed. In order to reduce demand on the system during peak demand periods and also to conserve water, flushing of urinals is carried out on a programmed basis. Urinals are flushed in groups of up to seven units by means of solenoid valves in their water supply, which are activated through the Building Management System. The flushing takes place in sequence with only one bank flushing at a time, thus reducing peaks in the water flow rate.
The flushing sequence and the time between flushes are pre-programmed based on the expected activities at the stadium. On non event days the flushing intervals are as much as six hours, whilst on event days the intervals are shorter; time is reduced to thirty minutes between flushes. This success of the system is aided through the use of waterless traps on all urinals, basins and sinks, which effectively seal smells and require little or no water flow to remain effective.
All the main systems related to the plumbing installation (pumps, water heating systems, tank levels, etc) are monitored by a Building Management System on a continuous basis, with alarms being made should any readings be out of specification.
Drainage Installation.
The drainage from the stadium consists of two separate systems, operating in parallel. One system serves general sanitary fittings such as toilets, basins, Hospitality Suite sinks and urinals, and the other system all the food kiosks and kitchens where the risk of grease and oil being discharged into the sewer system exists. This system takes the discharge through three grease traps, which are situated at the main outflows from the stadium, after which it joins the main sewer outflows to the external sewers.
Drainage pipe material is High Density Polyethylene, with heat welded joints. There are two main discharge routes, one discharging on the north-west and the other on the north eastern side of the stadium. In view of the enormous simultaneous discharge expected during break periods during events, special care had to be taken in the sizing of pipes.
As discussed earlier, extensive use was made of waterless traps on various waste fittings. These traps do not require a water seal and they are also not subject to the problems in terms of smell, loss of seals, noise, etc, which often plague conventional traps. They also allow the omission of certain ventilating pipe systems, thereby reducing the capital cost of the installation.
Fire Hydrant and Hose Reel Fire Protection System.
A separate fire main, coupled to the municipal main adjacent the stadium provides water to fire hydrants and hose reels to the stadium and its surrounds. A 200mm diameter ring main has been provided at lower Concourse level, from where rising mains supply the various end fittings.
The necessary fire brigade booster connections were provided at the site boundary as part of the site water reticulation.
Automatic Sprinkler Fire protection
All enclosed areas in the stadium building are provided with automatic sprinkler fire protection system, designed in accordance with SABS and ASIB Rules. Fire protection water is stored in a double concrete tank at basement level, and is pumped via a ring main to a total of seven sprinkler control valves, situated in control valve cupboards which are located at each quadrant on the external façade at Lower Concourse level. From the control valves water is reticulated to the protected areas via wet mains. The system is monitored for fault conditions via the Building Management System on a continuous basis.
Fire Alarm Installation
All enclosed areas in the stadium have been provided with a fire alarm system, comprising fully addressable detectors and call points, as well as a telephone communication system. The system comprises of a main fire control panel, situated in the Main Control Room at basement level, linked to another panel located in the Venue Operations Centre (VOC).
In order to prevent panic amongst large crowds, the alarm system alerts Stadium Security and Management of the alarm and is integrated to the Public Address System, the fire alarm installation triggers visible alarms in the form of flashing beacons for the hearing impaired. The evacuation of spectators in the event of a fire is then effected by the Stadium staff, along designated escape routes to safety.
The alarm system is linked to the Building Management System, which monitors its operation and makes an alarm should the system malfunction.
Vertical Transportation Systems.
A total of twelve elevators have been provided, six being dedicated passenger elevators, and six of which are dedicated goods elevators. A passenger elevator and a goods elevator is located at each quadrant of the stadium, and two passenger elevators serve the VIP and admin areas on the western side of the stadium. A goods and refuse elevator serve the kitchen.
The kitchen goods elevators were designed to allow the one elevator to move prepared foods from the main kitchen at basement level to supply a number of reheat kitchens at hospitality suite levels, where the food is stored at low temperature, reheated on event days and transported to the suites.
To prevent cross contamination between prepared foods and waste, a separate refuse elevator transports waste and dirty containers to the kitchen wash up area and waste handling section of the stadium.
All passenger elevators are capable of transporting stretcher bound occupants to concourse level for evacuation, if necessary.
Where required due to building constraints, hoists for the disabled have been provided to ensure that disabled persons have full access to all parts of the stadium.
Mechanical Contractors.
Plumbing Installation: Ezine Plumbers – JV between Kebble Plumbing, Industrial Plumbing, & Carrick Plumbing.
Domestic water composite pipe work: Smart Plumbers.
Hot Water Generation: SA Heat Pump Engineers
Pump Installations: MAH Pump Sales and Installations
Automatic Sprinkler Fire Protection Installation: Umlilo Protection Services
Fire Alarm Installation: HD Fire
Vertical Transportation Systems: Kone Lifts
Major Equipment Suppliers:
Drainage pipe work and fittings: Geberit
Waterless Traps: Hepvo
Domestic Water Pipe Work and Fittings: Galvanised – Robor, Composite - Upinor , Henko
Fittings: Taps, flush valves, urinal solenoid valves: Walker Crossweller,
Sanitaryware: Vaal Potteries
Domestic and Irrigation Water Pumps: Grundfoss
Fire Alarm Equipment: GEC
Lifts and Elevators: Kone
TRAINING
Due to the critical skills shortage in the construction industry, the Soccer City project embarked on an extensive training initiative to provide the necessary skills required by the project and to contribute to the development of the local community. A self-sustaining training centre was established by the Soccer City project near the site, in conjunction with a black economic empowerment (BEE) training provider. Training was conducted in the following disciplines, according to the relevant unit standards:
• Crane Operations
• Shutterhand
• Concrete hand
• Construction Supervisor
• Foreman
• Construction Plant Operator
All new trainees were assessed through a Learner Ability Battery Test, which is non-discriminatory and is used to determine literacy, numeracy, and development potential. All currently employed core and limited duration employees were offered the opportunity for further training and development to enhance their skills and further their construction careers. The training centre assessed 907 unemployed learners and trained 798 learners.