Crack assessment of the new galata bascule-type steel bridge

The New Galata Bridge connects the two sides of the entrance of the Golden Horn in Istanbul city of Turkey and as a bascule-type bridge, has four flaps, each having a span of 42 m. The bridge has replaced the original Galata Bridge, which gave service from 1912 to 1985. After the new bridge was constructed, serious cracks in steel stringers and near the counterweight blocks were observed during maintenance. As a result, modifications around these areas were made. In this study, fracture and fatigue analyses for cracks occurred in the original structural system were performed. For this purpose, a three-dimensional (3D) finite-element model of the third flap was prepared. Detailed computer analyses were carried out based on original drawings. The stress intensity factor values for cracks were evaluated by using 3D finite-element models and submodels of the bridge. To describe the notch toughness of the material in the vicinity of the cracks, a series of Charpy V-notch (CVN) tests were conducted. The results of the finite-element analyses were compared with the experimental evaluation results. The cracked locations of the bridge were clearly observed in computer model results. Based on these results, recommendations were provided.