Motorway BAB A13

This simple composite bridge crosses the 2x2-lane BAB A13 motorway between Dresden and Berlin. The discontinuous system has a width of 10.50 m and a bridge area of 498 m².

Concept

The girder system consists of three 900 mm high welded I-shaped steel girders. Prefabricated upper flanges were cast on the girders.

This bridge is typical of a simple short-span bridge built with prefabricated composite elements. An entire composite girder with concrete upper flange can be fabricated in the workshop (VFT-system).

Key benefits of using steel

The key benefits of this construction method are:

• Formwork and assembly bracings are not required.
• A high level of construction precision is possible as much of the work is carried out in the workshop.
• Use of the workshop also means there is little effect of the environment and the work is of a high quality.
• There is little disturbance of the traffic routes underneath the bridge during erection of the superstructure. The road only needs to be blocked when the prefabricated elements are installed.

Construction details

The steel girders – welded, open steel profiles – are welded in the steelplant and provided with full corrosion protection. The steel girders were transported to a prefabricated element plant, where prefabricated plates (100–120 mm thick) were concreted to the upper chord. The concrete plates of the girders serve as a formwork for the latter in-situ concrete deck. They also stabilise the steel girders during transport, assembly, and concreting of the in-situ deck.

The girders were taken to the site where they were lifted into the final position with a mobile crane. The girders were supported on the abutment, which was already been concreted. The frame corners were then concreted.. The large width of the prefabricated plates and the insertion into the frame corners stabilises the girders. No additional bracings are required.

Summary