Bridges

Bridges that are modular with standardised spans and profiles are well suited to fibre reinforced concrete. The beams and deck overlays can be produced more efficiently when all (or most) conventional reinforcing steel is removed. Steel fibre has been used in precast prestressed concrete beams to replace shear reinforcement.

Carriageway view of a double span bridge

Side view of the double span bridge using precast prestressed beams. Steel fibres were not used in the pier and cross-head, however there are opportunities for savings in construction, particularly for skewed bridges with complex reinforcing geometry. The beams are similar to the ones used for testing purposes (see notes below). With a hollow centre and broad flange the beam is suitable for quick installation and is immediately stable when landed on the bearings. Reinforcing steel is used only where primary bending forces will be applied a SFRC does not have capacity to resist these forces.

Example of a simple single span bridge.

Full scale testing has been completed of beams and analytical methods using fracture mechanics and plasticity have been developed. These methods have led to the development of design tools that can be used for a variety of structures.

There have been many tests of precast beams over many years in a number of research laboratories, however there are very few results for full scale beams. We believe this is relevant as acceptance of fibre reinforced concrete depends upon production within the existing framework, including moulds, concrete supply, work methods and transportation. Furthermore, there is need to meet code requirements and fortunately there are usually clauses allowing innovative builders and designers to base their design on tests.

 

 

 

   

Example Structures