Enhancement of riveted steel bridges by adding a trough in UHPFRC acting in composite action

Riveted railway bridges are commonly considered as being “old”, having fatigue damage and are therefore replaced. While this practice should be by now obsolete by using novel engineering methods like structural monitoring, prolongation of the service duration of railway bridges often requires an enhancement of the railway track system, in particular when there is an open deck with the sleeper-rail-system directly fixed on the steel structure. Three examples are described where the novel Ultra-High Performance Fiber Reinforced Cementitious composite material (UHPFRC) has been used to design lightweight trough and deck slab elements for new ballasted and fixed railway tracks respectively. Acting as a composite UHPFRC – riveted steel system, the structural resistance is significantly increased leading to important reduction of fatigue stresses. Subsequently, safety verifications at Fatigue and Ultimate Limit States are satisfied in view of future higher traffic loading