Carbon-reinforced variable module for short-span bridges suitable for precast concrete lightweight construction
The demand for durable bridges with short to medium spans has been increasing in recent years. Concrete is ideally suited for bridges of this kind. For achieving high durability with economical use of resources, the use of carbon reinforcement in concrete is advantageous since with this solution a drastic reduction in weight by minimizing concrete cover can be achieved. The VariBridge research project developed a steel-free reinforced, size-variable bridge module in carbon-reinforced concrete suitable for precast concrete in lightweight construction. It was designed in collaboration with the construction company Hans Graf Bauunternehmung, the engineering firm Schulze & Rank and TU Chemnitz. The solution was intended for spans from 5 to 15 m, with implementation and testing on a reference structure.
The thin-walled T-beam construction consists of high-performance concrete with closed structure and a combined steel-free reinforcement system of carbon grids, glass-fiber-reinforced plastic (GRP) bars and new GRP stirrups. It also features a new carbon angle lamella, registered for patent approval, that is integrated form-fit into the concrete during production. For technological implementation, a new formwork system is applied that, by using variable inserts, enables manufacture of various geometries. This development will be tested for the first time within the scope of a reference structure (a pedestrian bridge in Wesseling, Germany), to be constructed in late 2022. In summary, the VariBridge, through combination of the new steel-free reinforcement system and an especially developed concrete formula, allows significant reduction of component thickness while at the same time increasing service life to approx. 100 years. In this way, slender construction methods for bridges can be implemented on a resource-efficient basis.
