Study of UHPC Timber Composite Bridges for German/EU Marketability and Structural Design of Bridge Structure with One or Multiple Spans

Ultra High-Performance Concrete (UHPC) with fiber reinforcement (UHPFRC) in combination with timber beams has been used to sucessfully construct several compositebridges in Switzerland. This way of building allows for a fast and simplified way of construction. In contrast to conventional bridges, there is no need for additional roadway nor waterproofing.

This thesis analyzes the challenges of this composite construction method. The boundary conditions are adapted as much as possible to the standards valid in Germany. The calculation is carried out using an FEM simulation, which represents the circumstances with a high degree of accuracy.

Moritz Mitterbacher

Berlin University of Applied Sciences and Technology, Germany

Furthermore, four different options for shear transfer between the concrete slab and timber are compared and their suitability for bridge structures is analyzed.

The design of single-span bridges have proved that restrained stresses due to shrinkage as well as temperature and moisture change are critical. The combination of these loads occurs in the UHPC. In order to compensate for the tension exceedance, it is necessary to use a small amount of reinforcement in the bridge structure.

In the case of multi-span structures, supporting moments represent a similar challenge, which could only be compensated by increasing the UHPC ratio. This usually makes the construction of multi-span structural systems inefficient.