Cantilever

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Classic cantilever construction with prestressed concrete
Kochertal Bridge 1979

With cantilever refers to the construction of the stem free, particularly at bridges is applied. The following construction phase is added to the freely protruding end. The method is particularly used for bridges with large spans .

history

This manufacturing method was initially used for steel bridges . In reinforced concrete construction , the 68.3 m central opening of the Ponte Emílio Baumgart over the Rio do Peixe near Herval was first cantilevered in Brazil in 1930 . In 1951, the 62 m wide Lahn Bridge in Balduinstein was the first to be erected in the open front with pre - stressed in - situ concrete based on a design by Ulrich Finsterwalder . Just two years later, the same construction method was used near Worms to build the first prestressed concrete bridge over the Rhine with a maximum span of 114 m. With a span of 301 m, the Stolma Bridge has been the longest prestressed concrete bridge since 1998 that was constructed using lightweight concrete cantilever.

Construction process

In the classic cantilever structure, the superstructure is constructed symmetrically on both sides in the form of a balance beam, starting from the rigidly connected pillar. Due to the high bending moments above the column, the superstructure has a significantly greater height than in the middle of the field (e.g. at the Nibelungen Bridge in Worms or the Biaschina Viaduct in Ticino). Sections of the same length between 3.5 m and 7.0 m in length are made on the cantilevered scaffolding and formwork , which is attached to the front carriage, until the cantilever arm has reached half the length of the bridge span. The other half is made analogously from the next bridge pillar, nowadays the gap closure is monolithic, i.e. rigid, and in the past a joint was often built in. At a constant height, as in the Kochertalbrücke to reduce the cantilever moments were the cantilevered construction compression beam used or is stressed from an auxiliary support and stay cables. Analogous to the in-situ concrete bridges, cantilever bridges with many fields with prefabricated parts (cross-sectional segments) are often built, especially outside of Germany , whereby the assembly usually takes place with large mobile steel lattice girders. The reinforced concrete arches of arch bridges (e.g. Wilde Gera viaduct ) or the superstructures of cable-stayed bridges are usually erected with a cantilever structure suspended from auxiliary guy lines.

Examples

literature

  • Eugen Brühwiler, Christian Menn: Reinforced concrete bridges . Springer-Verlag, Vienna 2003, ISBN 3-211-83583-0 .