16.11: Experimental tests on the fatigue behaviour of thick‐plate trough railway bridges

ABSTRACT One of the basic aspect of sustainability assessment for bridges is the durability namely the fatigue resistance, because bridges are planned for very long lives of more than 100 years and suffer from high cyclic loading which may restrict lifetime of the bridge by fatigue failure. Nowadays final decisions on tenders are usually based on production costs and not on lifetime costs where a high performance in view of durability may pay off. Within a German FOSTA‐AiF‐research project an evaluation method for a life‐cycle assessment on railway bridges was developed and then applied on three different bridge types, exemplified by real reference bridges. For short spans, as an innovative bridge type, thick‐plate trough bridges were investigated because benefits in terms of sustainability were assumed due to the reduced construction time, simplified fabrication as well as prolonged durability through post‐weld treatment. Especially for the thick‐plate trough bridge, which was compared to different variants and an innovative composite bridge solution the sustainability assessment revealed high potential. This paper gives an overview on the fatigue investigations on thick‐plate trough bridges in the frame of this research project also in view of the weld improvement through Pneumatic Impact Treatment (PIT). Aims of these investigations were the improvement of single construction details and the characterization of the load‐bearing behaviour in order to identify the most critical fatigue detail for the fatigue assessment of these small span bridges with the help of experimental investigations and analytical methods.