ABSTRACT
The toughness of older steel structures is of crucial interest for the remaining lifespan and safety assessment of aging structures. Many structures in operation today were constructed during times when safety requirements regarding fracture toughness were not specified. This means that very little was known about the defect tolerance of such structures under various loading conditions. It is widely recognized that the toughness of common structural steels is strongly dependent on temperature and loading rate. Since the early 1990s, the Swedish Transport Administration (Banverket and Vägverket now Trafikverket) has conducted more than 600 fracture toughness tests on several hundred old steel bridges. The testing procedures were developed by the late Kjell Eriksson, who was affiliated with Luleå Technical University. The university has also conducted the majority of the fracture mechanics testing presented in this paper. This article will provide an overview of the fracture toughness testing conducted by the Swedish Transport Administration. The research leading to and background of the method used will be described. An example how the method is used for assessment of the load bearing capacity of older steel bridges in view of the toughness properties.
