The cherry on the cake

New materials and technologies as yet unprecedented in Brazil determine the trends in coverings for stadiums and sports arenas for the FIFA 2014 World Cup

With about a year and a half to go before the opening games of the FIFA 2014 World Cup, and only six months leading up to the Confederations Cup, the stage of progress in the construction of the stadiums that will host the competitions no longer keeps executives who are responsible for the tournaments in Brazil awake at night. Of the 12 host cities for the 2014 world football championship, only one - Natal (RN) - is still cause for concern, with only 42% of advancement in relation to the project schedule. The others are on schedule or even ahead of the initial timetable forecasts. The source of the assessment is Brazil’s Ministry of Sports and coincides with an independent survey conducted last September by Portal 2014 (www.portal2014.org.br) and released by the Sindicato Nacional das Empresas de Arquitetura e Engenharia Consultiva (Sinaenco - National Union of Architectural and Consultative Engineering Companies) and Editora Mandarin - a publisher.

According to the web portal, two and a half years after the start of work on the twelve World Cup stadiums (the pioneer was the Arena Pantanal in the city of Cuiabá, with works initiated in May 2010), four projects have already surpassed the 70% ready mark. They are: ‘Castelão’ in Fortaleza (CE) with 92% concluded; ‘Mineirão’ in Belo Horizonte with about 84%; the ‘Nacional de Brasília’/Mane Garrincha in Brasília (DF) with 81% done; and ‘Fonte Nova’ in Salvador (BA) with approximately 80% completed.

In the survey, the ‘Maracanã’ stadium in Rio de Janeiro (RJ) is reported to have accomplished 62% of advancement in construction works although the Maracanã Rio 2014 Consortium, consisting of the Odebrecht Infraestrutura and Andrade Gutierrez construction companies, claims to have reached a milestone of 75% of the work completed.

The months of July and August of this year displayed the highest rates of progress on record in the execution of the stadium construction projects. The biggest leaps forward were in Belo Horizonte and Brasília, with 11% and 10%, respectively.

Dangling at the end of the list in progress achieved, the ‘Arena das Dunas’ in the city of Natal is presently at the stage of assembling the stadium’s spectator stands. The installation of the support beams for Sector West of the upper ring of the spectator stands (a.k.a. ‘raker beams’ - nicknamed locally “vigas jacaré” or ‘alligator beams’) began in October. In the lower ring, in turn, Sectors South and West have already been completed and the East Sector is being finalized. Some 1,200 workers are involved in the construction which is under the responsibility of Construtora OAS, which holds the 20-year concession on the stadium under the terms of a Public-Private Partnership (PPP). The project is budgeted at R$ 417 million (US$ 208.5 million).

Innovation speaks louder
In stadiums where progress is more advanced, the works are already focusing on the assembly of coverings - which is considered a very complex step since it involves technologies that are unfamiliar to or have been little used by Brazilian engineering. In almost all of these projects both the components of the coverings and the know-how involved in their assembly have been procured and engaged abroad.

Among the various alternatives available, two have been establishing themselves as the trend in the solutions chosen for most of the country’s stadiums: the use of tensile membranes supported by steel trusses and cables, and polycarbonate panels combined with metallic structures.

Both solutions satisfy the criteria of comfort, safety, functionality and aesthetics. With regard to the latter of the four criteria, what is observed is that architects and designers are seeking, by choosing these covering elements, to give these stadiums harmonious and balanced lines taking the utmost advantage of these coverings’ visual effect.

In addition, the requirement that the field of view from anywhere in the stadium should be completely free of obstruction limits the placement of pillars inside the stadium, thus requiring designers to adopt structures that are light but that provide high structural strength and the ability to overcome large free spans. The covering, furthermore, has to provide satisfactory levels of resistance to the wind, impact, and variations in temperature.

The lightness of tensioned structures
Structures using tensile membranes, or ‘tensile structures’, are produced from glass fiber covered with multiple plies of “Teflon" (a compound consisting of fluoropolymers) with a gauge or thickness of around 0.76 mm. These structures consist of high-strength membranes upon which tensile stresses are brought to act. Since they are translucent and waterproof, they perform well in such applications in view of their ability to reflect light and deflect heat by over 70%. These materials do not degrade when exposed to ultraviolet rays or when subject to dust and dirt, and they are easily washable. They ensure a good visual result since they enable bolder architectural forms than traditional alternatives.

Compared to a conventional concrete or metal structure, these tensile structures are up to two-fold lighter. This feature is key when the challenge to overcome large spans.

Tensile structures furthermore have excellent acoustic performance; producing little reverberation. The tensile membrane is more ‘permeable’ to low-pitched sounds (basses) and reflects most of the high frequencies or trebles.

This solution, however, cannot be regarded as an alternative that provides lower cost. The execution of each project requires electronic and physical mock-modeling, special     calculations and detailing, and the specification of mostly foreign-made material to ensure durability and good appearance even after many years of use.

200 times stronger than glass
In turn, the use of panels of polycarbonate - which is obtained from resins derived from carbon - is a solution which is light in weight and provides high mechanical strength. The resistance of this material can be, on the average, 200 times greater than that of glass and 30 times greater than acrylic. Thanks to its characteristic translucence, ability to deflect and reduce heat and resistance to impact, polycarbonate is widely applied in civil construction.

Polycarbonate sheets or panels are used chiefly when you want to capitalize on natural lighting since the material delivers 98% transparency. But polycarbonate sheets can also be produced in different shades of color for varying degrees of sunlight control. Easily curved when cold, the polycarbonate sheet allows great flexibility in the shape of coverings, enabling light-weight structures. Fixed or retractable, with or without permanent ventilation, the coverings may also be reflective, thus reducing the transmittance of solar energy by 25% to 40%.

The material can be found on the market in two presentations: as compact or as honeycomb panels. Honeycomb polycarbonate panels are smooth on the outside with internal cavities known as alveoli. They block 100% of the sun’s UV rays, do not yellow readily, transmit light well and are highly resistant. They are lightweight, easy to install and can be cold-formed (curved) at the job site.

Compact polycarbonate panels have the same technical characteristics of honeycomb panels but are heavier and more expensive. They are completely smooth in appearance and transparent and are very good substitutes for the ‘look’ of glass.

Fonte nova takes the lead
The ‘Arena Fonte Nova’ in Salvador, Bahia was the first among Brazilian stadiums to begin the assembly of its covering ( 25% of which has been concluded) using tensile membrane technology over a structure consisting of 290 tons of cables and trusses made of a metallic alloy. Similar to a bicycle wheel, the system has an outer ring with a metallic structure connected by cables to two other rings. One of these rings provides tension while the other provides compression, working together. That’s 9.2 km of steel cables which weigh a total 290 tons. The metal structure of the compression ring weighs 1,198 tons and the structure of the tension (pull) ring weighs another 586 tons. The membrane has 28,000 m² in area and the area of the metal deck is 8,350 m². No less than 144 masts were assembled to separate the two supporting rings.

To hoist this structure a process known as ‘Big Lift’ was adopted. This is the first time the system has ever been used in Brazil and the second time in Latin America. In it, the cables are raised with the help of 36 hydraulic jacks imported from Switzerland, each capable of lifting up to 220 tons. The jacks work together and are computer controlled. Technicians from Germany, France, China and Portugal came to Brazil especially to control the process.

The ‘Big Lift’ was performed in two stages. Stage one was the lifting of the upper traction ring. Then came the suspension of the lower ring. The whole process took about a month and a half. Lifting of the cables that will sustain the covering was completed on November 9th.

Sustainability
The design of covering for the Arena Fonte Nova has decreased the consumption of steel by 40%. Furthermore, much of the steel that has been used comes from recycled material. Another feature of the covering is its ability to collect rainwater. The structure was designed to collect 37,000 m³ of rainwater annually to be used in housekeeping, in the 94 stadium restrooms, and for irrigation of the playing field.

This represents savings of 72% in water bills during the rainy season and 24% during the dry season. The total rainwater storage capacity in the design of the Arena Fonte Nova is 698,060 liters.

Mountain climbers install covering of Maracanã
Also at the Maracanã Stadium where the works have entered the final stretch, lifting of the cables that will support the roof membrane (which is made of fiberglass and teflon) has begun. The covering implementation project has been assigned to German firm Schlaich Bergermann und Partner (SBP), which is also responsible for the covering of the Mineirão Stadium where metal structures with polycarbonate panels are being used.

But as regards the Maracanã Stadium, the solution adopted for the installation of the covering was very ‘original’: a team of 30 mountaineers was specially trained to lift the structure with the help of four cranes and 120 hydraulic jacks. As in the Arena Fonte Nova, the Big Lift system was also adopted for the stadium in Rio de Janeiro - a job that began on November 25th and should take two weeks.

Before reaching this stage, 60 metal parts were fastened to the top of the stadium to form the compression ring. Each part weighs 40 tons. The last part of the ring was placed on Aug. 22nd. Following that, four scaffolds were installed for the assembly of the catwalks and two support platforms were erected on the spectator stands to provide support for the pre-assembly of steel cables that are used in supporting the covering.

Once the structure of the tension and compression rings is hoisted, it will be time to ‘lace up’ the tensile membrane with the help of professional climbers with the support of cranes - an activity that is expected to take two weeks. The membrane will be 68.4 meters long and will provide cover for about 76,000 of the more than 79,000 spectator seats.

According to Claudio Casares, assembly manager for the Maracanã Rio 2014 Consortium, which is comprised of Odebrecht Infrastructure and the Andrade Gutierrez construction companies, the decision to use professional mountain climbers for the assembly of the covering took into account the operational complexity of the task. “During the work of planning, we saw the need for this type of skilled labor due to the impossibility of having two cranes occupying the same space. Therefore, we hired experienced professionals from the market, but due to the need for a greater number of these experts we decided to qualify workers at the work site itself to handle this type of service. We conducted a selection and trained 17 people who can now exercise this profession for the rest of their lives,” Casares said.

Covering with a distinct touch of sustainability 
The project for the renovation of the Mineirão was designed with a restriction: preserve the stadium’s original architectural features since its facade is listed for preservation by the ‘Cultural and Historical Deliberative Council’ of the city of Belo Horizonte. Thus, all the interventions are being made in the interior of the stadium, below the level of the restriction. In addition to the restrictions, the project is guided by concepts of sustainability since one of the goals of the work being done to modernize the Mineirão is to obtain the LEED (Leadership in Energy and Environmental Design) seal of approval, which certifies that the stadium is an environmentally sustainable venture.

As part of this project, the Mineirão will receive a new metal-frame covering and translucent polycarbonate panels which will complete the concrete covering that is already in place. This metal-polycarbonate covering will be supported by a tension ring and steel cables suspended from an independent structural system which will not cause any interference in the ‘volumetry’ of the stadium.

The covering will furthermore receive a set of photovoltaic panels to generate electricity from sunlight. The covering also collects rainwater for irrigation of the playing field and for use in the restrooms. Two electronic scoreboards will be mounted on opposite sides of the new covering.

A race against the clock

BELO HORIZONTE
The works have reached 84% of accomplishment and should be delivered in December this year. The turnstiles as well as seats for players on the sidelines, most of the spectator stand seats and even some of the stadium reflector lights have been installed. The new covering is almost ready. The playing field is undergoing leveling which will enable its preparation for drainage.

BRASÍLIA
Works are at 81% completion and should be ready in February 2013. The upper spectator stand is almost ready and activities are now focused on the installation of the covering which consists of a tensile membrane. In November, work was begun on hoisting of the cables and mounting of the supporting metal trusses that will form the base for the placement of the membrane which will have 90,000 m² in area.

CUIABÁ
The Arena Pantanal reached 50% completion and is scheduled to be fully concluded by July 2013. So far, only the installation of the spectator stands in the West Sector has been completed. The metal structures of the North and South Sectors began receiving the steps of the spectator stands. About 700 workers are working on six different fronts at the construction site.

CURITIBA
The project has achieved 52% of completion and work is being done on the existing part of the arena and also on the Brasílio Itiberê Sector which will receive new stands, locker rooms, a press agency section, VIP area, hospitality area and parking. Around 430 workers are at work. The greatest advances were in the new area of the stadium, on the second floor and in the entrance to the Arena da Baixada. In all, four sectors are still being demolished.

FORTALEZA
The Castelão Stadium is at 92% of works ready and delivery is scheduled for December this year. Activities focus mainly on three points: the assembly of the covering, the playing field and the installation of the spectator seats. In October, Castelão began receiving its glass skin which will make up its facade. On the covering, sandwich-type metal shingles (consisting of two-sheets of metal with an insulating foam filling in between) also began to be placed.

MANAUS
Work on the Arena Amazônia is at 45% of physical progress and completion is scheduled for December 2013. In early November, the stadium received the second installment (R$ 37 million - US$ 18.5 million) of a loan granted by the BNDES. The expectation now is that work on this arena will gain new thrust.

With completion scheduled for December 2013, the works of the Arena das Dunas have reached a level of 42% accomplishment. The delay is the result of a succession of three labor strikes among its workers in eight months. In mid-October, the OAS construction company began installing the beams of the West Sector of the upper ring of the spectator stands. The assembly of the West and South Sectors of the lower stands has already been concluded.

PORTO ALEGRE
The renovation of the Beira-Rio stadium has reached 45% of physical progress. The foundation works in quadrants 2 and 3 of lower spectator stands are almost finalized. In the next step, the precast elements for the stands of quadrants 2, 3 and 4 will begin to be erected. Also being performed are the construction services under the stands in quadrant 1. The bottom ring should be closed by the end of this year; 500 workers engaged in this construction which should be completed in December 2013.

RECIFE
The works on the Arena Pernambuco have reached 70% completion. At this time, the work is focused more intensely on the assembly of the covering on the South wing of the stadium which is 66% ready. The stadium is expected to be delivered to the public in February 2013.

RIO DE JANEIRO
Maracanã has 75% of works completed. The last precast element of the spectator stands and final compression ring of the covering are being placed. The playing field has already been demarcated, with leveling and drainage. Planting of the playing field turf should occur after the assembly of the covering when the gantries and cranes leave the site. The same also goes for the installation of the spectator stand seats.

SALVADOR
Progress of the works reached 80% in August with completion of the assembly of the project’s superstructure. The superstructure - consisting of pillars, beams, slabs and the spectator stands - has been concluded. The finishing stage began in July. Right now work is focused on the assembly of the covering. Excavation has begun to plant the playing field. The stadium is scheduled to be inaugurated on March 29th, 2013.

SÃO PAULO
The Arena Corinthians is at 55% completion. Completion of the work is still scheduled for December 2013. The fifth module of the covering was hoisted in the East Sector. In all, the sector will receive 10 parts of the covering. On the West side, 12 modules will be installed. Since late September, all the steps of the East Sector spectator stands have been installed. In the West Sector, this stage of construction is almost ready. On that side, an eleven-story building will be erected for the VIP areas.