DISPLACEMENT INDUCED FATIGUE CRACKS

The interaction of the various components of a bridge structure under regular truck or train traffic has frequently resulted in cracking in unexpected locations in relatively short periods of time. In welded girder type bridges this cracking has often occurred in the web at short gaps between transverse connection plates and the girder flanges. This paper examines two cases of fatigue cracking at such short gap conditions. Strain measurements and a detailed analysis are used to demonstrate that such cracking results from the out-of-plane movements of the web in the short gap region. The study demonstrates that the most reliable means of preventing this type of cracking is to connect the transverse connecting plates to both top and bottom flanges. © 1979.