Masterly stand renovation

Special formwork and architectural concrete: renovation under complex conditions

Flashback to the summer of 2022: After the demolition of the last existing part of the stand, a race against time began for ARGE 1893 Ed. Züblin AG / ROM Technik GmbH & Co. KG. The new stand with the tiered seating for the spectators was already available in August 2023, in time for the start of the new season. All remaining work will be completed by January 2024. Players, officials and more than 60,000 spectators will then be welcomed to a top-class arena. And when all eyes in the football world turn to Stuttgart for five games during the UEFA EURO 2024, there will nothing to remind them that the heart of the stadium’s infrastructure had been operated on under high pressure within the existing structure while the team was playing regular league games.

From the outside only the tiered seating for the spectators can be seen. However, in the interior of the main stand a lot more is being created: a players’ section with changing rooms, function rooms for officials, press room and media centre, TV studios, a restaurant kitchen, maintenance areas, sanitary rooms and lifts. The routes for the spectators from the entrance gates to the stand and back again are being optimised in accordance with high safety standards. In an exclusive business area the spectators are almost within touching distance of the stars as they make their way between the changing room and the pitch.

Time pressure and shortage of space

The very tight time schedule, in particular, is a challenge. Every week counts, as the loss of thousands of seats in the tiers for the spectators and in the business areas costs valuable income. However, there was already an unpleasant surprise during the demolition of the old stand: The existing foundations were not, as expected, in good condition. Structural engineers and experts had the final say, new authorisations had to be obtained and finally in January 2023 400 m³ of concrete were poured. The experienced construction team made up for the resulting delay by speeding up the construction work.

As there was hardly any space between the pitch and the stands, meticulous construction site logistics were indispensable. The complexity of the many different building structures required comprehensive preparation: MEVA created more than 100 formwork plans and a multitude of assembly plans for special formwork. The work required before each game was also considerable: The construction site had to be cleared, secured and hidden behind panels. It was not possible to use tower cranes in the interior, making it necessary to use a great many mobile lifting devices. A large part of the ongoing forming work is currently being performed in the existing structure, often in areas under existing slabs that are difficult to access. The interior walls of the stand were poured in a very confined space and, due to the tight time schedule, at the same time as the spectator terraces. The lightweight and stable hand-set formwork AluStar played to it strengths here: low weight, robustness and simple handling.

When it was possible to receive assistance from a crane located in the outdoor area of the stadium, the work was performed using the high-performance wall formwork systems Mammut 350 and Mammut XT. For the construction of the entranceways and outdoor staircases, Mammut 350 proved to be the ideal choice: A high architectural concrete quality was achieved thanks to the harmonious, symmetrical joint and tie hole pattern and the alkus all-plastic facing fitted as standard. The 9 m high guide walls were poured using Mammut XT: Despite the wall thickness of 72 cm, the single-sided tying with tying positions symmetrically offset away from the edges of the panels posed no problems.

Cleverly combined shoring towers

Thanks to their flexibility, the MEP and MT 60 shoring towers made the work easier, for example when supporting overhangs and slabs that were to remain in place or be demolished in order to make room for stairwells and lift shafts. Corresponding constructions were erected using the MT 60 shoring tower, Triplex SB heavy-duty props and EuMax props. The MT 60 shoring tower was also used for the construction of 40 cm thick slabs with concrete beams and scaffold heights from 5 to 8 m, often combined with the MEP shoring tower. Slabs with scaffold heights up to 5 m were poured using MevaFlex.

Toothed beams and V-shape supports

In early 2023 twenty-four imposing toothed beams, each with different designs, were poured on-site. They act as crossbeams to support the floors of the stand that are made up of precast concrete elements. The original plan was to prefabricate the toothed beams and have them delivered to the stadium, but this was rejected for weight and transport reasons. The formwork had to be produced in special shapes that could not be achieved using standard formwork systems. MEVA’s department for special formwork planned the creation of the teeth using hundreds of special wooden panels with dozens of different dimensions. First of all 3D models were created, which enabled quick decisions to be made.

Each toothed beam has steps with varying depths and heights. The spacing and heights differences between the seat rows vary, as the inclination of the stand increases from about 30° in the lower section to about 40° in the upper section. For this reason, the lower edges of the toothed beams also have changing gradients. Two toothed beams are connected directly to the balustrades of the new players’ tunnel. After installation of the initial formwork (Mammut 350) and lower boxes, the MEP shoring tower system was installed to provide support in the ascending area. The rebars were then installed, upper boxes fixed to special brackets, the final formwork set up and the concrete poured in through openings on the top side.

Four V-shaped, 50 cm wide supports were also poured without problem. These support the 70 cm wide toothed beams. To compensate for the 20 cm difference in width, the Mammut 350 panels for the initial and final formwork were each doubled up by 10 cm. Initial formwork installed, insert boxes fixed in place, rebars and final formwork installed, concrete poured. The final formwork was now removed in the upper area, rebars and special wooden panels for pouring of the toothed beams were installed, the final formwork was anchored, and the concrete poured. The V-shape supports and toothed beams shine in architectural concrete quality that exceeds the SB2 quality required by the principal and blend into the flawless overall appearance of the old, new stadium.

MEVA systems:

• Special designs
• Mammut 350 
• Mammut XT wall formwork
• AluStar wall formwork
• MT 60 shoring tower system
• MEP shoring tower system
• Triplex heavy-duty props
• EuMax props

Contractor:
Arge 1893, Ed. Züblin AG / ROM Technik GmbH & Co. KG, Stuttgart

Principal:
Stadion NeckarPark GmbH & Co. KG, Stuttgart

Architect:
asp Architekten GmbH, Stuttgart

Project:
Modernisation of a football stadium, Stuttgart, Germany

Engineering and support:
MEVA Schalungs-Systeme GmbH, Haiterbach (D)