Frankfurt Airport with new air connections


Cross section of the frame structure
Continuity prestressing cable at intermediate support
Erection of concrete girders for the bridge structure
Finite Element Model

In October 2011, the operating company of Frankfurt Airport, Fraport AG, commissioned a global innovation in infrastructure construction, comprising two taxiway connections with a total of five bridge structures, where landed aircrafts taxi to the two airport terminals - crossing a highway and the railroad tracks of Deutsche Bahn!

After completion of the building project, aircraft movements in parallel are possible in Frankfurt. Thus, the airport will be able to cope much better with the continuously increasing demand of passengers and the transport company. According to current forecasts, about 90 million passengers will arrive, depart and transfer at Frankfurt per year by 2020.

Considerable time pressure

Fraport awarded a contract for the construction of the project to three of the major construction companies in Germany: The group of companies Max Bögl, loca-tion Sengenthal, Ed. Züblin AG, a subsidiary of STRABAG, location Frankfurt am Main, and Leonhardt Weiss GmbH & Co. KG, Satteldorf.

The know-how of experts was required, in particular, during design and construction planning in order to meet the completion deadline. Because the time frame was more than tight. In April 2008, planning started for the five highly sophisticated bridge struc-tures with an overall bridge deck area of 40,000 m² at Frankfurt Airport. The Hamburg-based engineering office Dr. Binnewies, as the planning office in charge with this task, was faced with the challenge to draw about 600 formwork plans and about 800 reinforce-ment plans in hardly 16 months and to submit the same to the construction site in due time.

The two taxiway connections pave the way for the aircrafts coming from the new runway north of the A3 highway and the high-speed track between Frankfurt and Cologne to the airlines operations area in the south. The engineers designed three taxiway bridges for the eastern taxiway and two further ones for the taxiway in the west - considering extremely complex conditions for smooth construction works: At 30 de-gree (30 Gon) the crossing angles are very pointed, the bridges more than 200 m wide and the dimen-sional load for the aircrafts accounts for substantial 750 tons. Furthermore, there are limited overall heights of approx. 200 cm and the construction works had to be carried out when traffic was moving. Not to mention the complexity of the building geometry be-cause all five civil engineering structures are different.

Shorter construction time due to precast components

A closer look at the design principle of the taxiway bridge EAST 1, which was transferred to the bridge structures WEST 1 and EAST 2, indicates the difficul-ty of the task. The Binnewies office had to develop a new design concept. The initial design - a cast-in-situ concrete construction with a solid 200 cm thick super-structure - was given up, among others, owing to a longer construction time required. The new idea pro-vided by the experts from Hamburg that was finally realized at the airport: a prestressed integral frame structure made of precast prestressed concrete ele-ments with T cross-section supplemented with in-situ concrete. 

The foundation of the pier and abutment walls was built on restrained bore piles. Upon the same, seam-less abutment and pier walls were erected. The su-perstructure was finally realized with precast pre-stressed concrete elements, cast-in-situ concrete topping and continuity prestressing. In the first step, the precast girders were installed. These were pre-stressed by the factory with subsequent bond and including jacket tubes for the later continuity pre-stressing. 

Easy to use

The Hamburg-based engineers scrutinized various system solutions in the field of structural engineering. The decision was made in favor of an innovative solu-tion of the portfolio of the Stuttgart-based software designers RIB that was so far rarely tried and tested in practice. The RIB system PONTIcompositeconcrete was applied for the overall modeling of the taxiway bridges, the design of the pile head widths and abut-ment walls as well as for the cast-in-situ concrete topping. "We attached great importance to design a model that is easy to use but at the same time pro-vides the complexity required in order to fulfill the task in an optimum way," states Schmidt, the project manager of engineering office Dr. Binnewies. 

In order to make optimum use of the software under conditions in practice, the experts of the R & D team of RIB Engineering GmbH supported Schmidt and his team extensively. This was also challenging for the experts of RIB because the new program had to prove its practical feasibility directly under extreme conditions. The success in the design process speaks for both a high quality of the product and the communication between the software provider and the engineers. Only detail analysis had to be calculated manually, for instance, fire protection design and earthquake design. ZWAX was applied for pile dimensioning, which is another product of the Stuttgart-based software designer RIB. 

Industries>Architecture, Engineering & Construction>Architects and Engineers>Binnewies Engineering Office

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