Innovative Method for the Production of Deck Slabs of Steel-concrete- Composite Bridges

Different methods have been developed for the production of deck slabs of large steel-concrete- composite bridges. Often such deck slabs are cast with in-situ concrete with the aid of a formwork carriage. In order to speed up the construction, construction methods with pre-past partial-depth or full-depth elements have been employed. Usually a crane is needed for the placing of the pre- fabricated elements.

A patent for a new construction method for deck slabs of steel-concrete-composite bridges was recently granted to TU Wien. The innovative feature of this novel method consists in the combination of the advantages of in-situ construction using a formwork carriage with partial-depth elements. First, pre-fabricated elements for a section of the deck slab with a chosen length of for example 25m are placed at the assembly area. Reinforcement is placed on top of the pre-fabricated elements and a first concrete layer is cast on top of the pre-fabricated elements. Then a carriage, which can travel along the whole length of the bridge like in the case of a formwork carriage, moves the precast elements to their final location by lifting them approximately 400 mm and then transporting them where ever they need to go. Finally an in-situ concrete layer is added on top of the elements. When the in-situ concrete has gained enough strength, the prefabricated elements, which serve as a lost formwork but also become a load carrying part of the deck slab, are detached from the carriage. This construction process is repeated until the entire bridge carriageway is constructed.

The essential advantage of this innovative construction method for the production of slabs for bridges is the reduction of construction time and the production of a deck slab with the same quality as an in-situ concrete slab.