Support frame concept from MEVA plays to its strengths in a very confined space
An important future-oriented public-transport project is being carried out in Vienna: the central transfer hub in the inner-city metro network. The extension in the middle of the city requires tightly scheduled construction plans, optimum processes and clever solutions from the Arge U2xU5 consortium responsible for the project.
Austria’s capital will soon have more than 2 million inhabitants and the amount of traffic already reaches its limits on a daily basis. The city of Vienna is thus expanding the public transport network. Having already completed several development projects, the gap is now being closed through the extension of the crossing point of the U2 and U5 lines in the busy city centre. The new U5 line should be completed in 2026, followed by the modernised U2 in 2028. The centrepieces are the new Rathaus station, that is presently being built under the current station at a depth of 30 m, and the Frankhplatz station. The construction in the heart of the pulsating city, between countless tunnels and pipelines below the surface, the general problem of space and the corresponding logistical difficulties place heavy demands on the responsible parties.
Reliably calculated using MietePlus
Due to the limited space available below ground, the Arge U2xU5, a consortium formed by the construction companies Swietelsky, Habau and Hochtief, requires compact and flexible systems. The wall heights range from about 3 to almost 9 m. MEVA delivered support solutions for the single-sided forming of facing shells using AluStarTec and Mammut as well as Triplex heavy-duty props – as part of the comprehensive MietePlus package. The customer thus enjoys costing certainty during the entire project, as besides rental and logistics, all services such as cleaning and repairs are included.
In 2022 the beams and floor slabs were produced for the shafts with depths up to 30 m – partly using the cut-and-cover construction method to enable the surface at ground level to be used again quickly. At the same time, all necessary anchorage parts were planned, delivered and installed. The facing shells will be poured on the platforms and entranceways by 2025. The concrete is mainly being poured into the formwork via filling nozzles and compacted using external vibrators powered by compressed air.
Unique support frame concept
Walls with a total length of about 550 m are being poured in the stations Frankhplatz and Rathaus. Constantly changing heights require numerous adjustments of the single-sided formwork and support in a confined space. The MEVA support frame concept allows a lot of time to be saved with minimum effort below the city’s surface due to a unique selling point: The formwork is placed horizontally in front of the robust STB 300 Plus and STB 450 support frames. Varying heights can now be simply catered for in small steps, corresponding to the available panel widths, by adding or removing panels. Normally, a construction made up of formwork and a support frame would have to be completely dismantled, height-extended from below and then reassembled even for small changes in height. This is unnecessary work, as the advantages of the MEVA support frame concept are perfectly clear and please every civil engineering company: rapid construction progress and a high level of cost-effectiveness.
The loads that occur are distributed according to the requirements. Sometimes the support is only anchored at the bottom, sometimes at the bottom and at the top. The MEVA support frame thus serves as a beam if required. This reduces the load acting on the intermediate slabs and reduces the amount of work required as well as the costs. To efficiently support the load, Triplex SB heavy-duty props are attached to the height extensions and base extensions of the STB or to the floor slab. If no space is available on the ground, the flexible Triplex SB are simply fastened to the opposite wall or to the slab.
The STB support frames have a compact design and can be easily transported by crane or moved, as is the case during this project, on swivel-type castors. With a depth of only 2.45 m, the STB 450 are transported by lorry and stored in a space-saving manner. Formwork with heights up to 13.50 m can be reliably supported using STB height extensions.
Architectural concrete for everyone
The new Rathaus and Frankhplatz stations are intended to awake the desire in car drivers to switch to public transport. Concrete surfaces that meet high design standards will please the eye of the beholder – with architectural concrete surfaces in S3/A3 quality in accordance with ÖNORM B 2204 or in SB3 quality, smooth or with joint pattern. The alkus all-plastic facings fitted as standard to all MEVA formwork systems paid off here.
(Fotos © Arge U2xU5)
MEVA systems:
- Special design
- Mammut
- AluStarTec wall formwork
- STB and SK brace brackets
- Triplex heavy-duty brace.
Contractor: Arge U2xU5: Swietelsky, Habau, Hochtief, Vienna, Austria
Principal: The city of Vienna
Architect: Zechner & Zechner ZT GmbH, Vienna, Austria
Project: Arge U2xU5 Rathaus/Frankhplatz, Vienna, Austria
Engineering and support: MEVA Schalungs-Systeme Gesellschaft m.b.H., Pfaffstätten, Austria.
