The inspection of several dozen bridge structures (over 80) along the Wroclaw- Poznan railroad line whose aim was to determine the feasibility of adapting this line to the running of trains at the high speed of 140-160 km/h revealed numerous cracks in short steel bridges having the span of 12-18 m, particularly at the places of various joints. This paper shows several examples of such cracks. An attempt is made to explain their nature and genesis. Also several ways of repairing effectively this kind of dangerous damage to bridge structures are demonstrated. A description of the weld cracks, discovered during expertise and field test work, in structural components of the wind bracings in a steel three-span railroad bridge with simply-supported spans and an open deck situated on the Wroclaw-Poznan railroad line is presented. The probable causes of the cracks and the character of the latter as well as possible methods of repairing this damage, with stress put on the correct shaping of the geometry of the structural members, are discussed. The conclusions that emerge from these considerations are applicable to similar cases of fatigue damage to structural components of steel bridges.
Samenvatting