North-South-Railway of the RWE Power AG
Condition assessment of the bridge stock
The north-south-railway of the RWE Power AG was utilised for the transport of brown coal and overburden between the opencast minings and coal-fueled power plants in the Rhenish brown coal area. It was erected in the 1950s, and today, it sports a total track length of more than 30 km. Hereby, the track route boasts several bridge structures, the majority of them being constructed via steel concrete construction method, offering a span of 7-11 m. So these bridge structures have been in service for approx. 60 years, nearing their limit of 70 years, as proclaimed by the replacement guideline for bridge structures.
For the strategic planning of the measured planned for the immediate future, respectively the maintenance of the north-south-railway, ZPP was commissioned with the assessment on how the technical condition of the bridge superstructures really presents itself.
The decisive factor for the assessment was the level of material fatigue concerning the steel concrete construction, especially the strengthening steel. In order to precisely estimate this fatigue progress for the bridge superstructures, a calculation that performs as realistic as possible was pursued, based on calibrations.
After a first inspection of the existing documents in the form of shelling and strengthening designs, as well as the static calculations, the three randomly sampled bridges A 2, A 3 and A 37 were visually inspected on-site. Subsequently, the deformation behaviour of the superstructures, both as fast, as well as at extremely slow train crossings, was measured.
Finally, calculation models for all three bridges were created based on the results of the measurements, then subsequently analysed in the state of fatigue.