Aspects of structural degradation in steels of old bridges by means of fatigue crack propagation
Abstract
We present conclusions drawn from the studies related to old steel structures, especially those erected on the turn of the 19th century. The objects of interest of the authors are the Wroclaw Pomorskie Bridges: the Central Pomorski Bridge and the North Pomorski Bridge (1885 and 1930, respectively), as well as the Sand Bridge (1861). The material used for their construction was puddled steel or cast steel. In the course of long-term operation, these steels (especially puddled steel) show susceptibility to degradation processes. We present the results of metallographic tests (light microscopy and SEM) and mechanical-properties tests (hardness measurements and static tensile tests) describing the state of structural degradation. In addition, the results of initial study for the puddled steel coming from the Sand Bridge and concerning the development of a fatigue crack are presented. Basic quantities describing the kinetics of fatigue crack growth are determined.
