Timber-concrete composite bridges consist of a block beam or several girders consisting of laminated timber which are connected with a concrete slab on the top on a rigid basis with specialist connection systems.
The concrete slab can function directly as a road surface or also gain a mastic asphalt surface. With the concrete slab on the top, the further bridge construction can be designed in accordance with a conventional concrete bridge. In this respect there are clear rules for which technical details are available and which simplify the design.
The structural protection of the timber is ensured by the sufficient overhang of the concrete slab over the timber structure.
Hybrid is understood as being a technique in which the benefits of two technologies or materials are optimally combined with each other. Timber-concrete composite bridges are an example of such a hybrid design. They combine the benefits of timber with the advantages that result from the composite construction.
In this respect, the concrete slab is arranged in the pressure zone and serves the purpose of a roadway. The timber, in contrast, is placed in the tensile zone as the main girder. This means that a considerable amount of the tensile stress is absorbed by the timber, whereby the reinforcing and dimension of the concrete slabs can be hugely reduced.
This mix of timber and concrete has the potential to change bridge building in Europe on a sustained basis. Due to the natural material of timber, the bridges slot into natural settings very harmoniously. Their combination with concrete, however, also provides them with significant load-bearing capacity and durability.