PSI - Issue 64

Julian Unglaub et al. / Procedia Structural Integrity 64 (2024) 918–924 Julian Unglaub / Structural Integrity Procedia 00 (2019) 000–000

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adapters allow easy installation. The coating system does not have to be removed. The clip-on extensometers are used to measure the gap opening in the immediate vicinity of the crack. In addition, measurements can continue to be taken on one side during the repair work. This allows documentation of the actual conditions during repair.

Fig. 1. Measurement setup with clip-on extensometer at the Rhinebridge Duisburg-Neuenkamp, Begemann et al. (2024).

In addition to recording the gap opening and the central time recording, the global temperature is also measured. All data is stored in a central monitoring unit (Gantner-Instruments 101 DT) via measuring amplifiers (Gantner Instruments, Q bloxx A106). The measurement technology used was used to record the data at a rate of 200 readings per second. The long-term monitoring was carried out at the Rhinebridge Duisburg-Neuenkamp over a period of three weeks. When evaluating the measurement data, it was assumed that local deformations are small compared to the crack opening, because the compact measuring system is located in the immediate vicinity of the crack. The initial measurement assumes the crack to be in an almost closed state. The vehicle crossings result in rapid changes in the signal. With a measuring rate of 200 measured values per second, the vehicles can be recorded axis by axis. This statement was confirmed by comparison with temporary traffic recordings. The measurement location is directly above the load introduction from the axle loads from the truck lane. The individual vehicle weights are not known. Reference values for the amplitude and frequency of the gap opening can be derived from the height and spacing of the peaks in the signal. Crack openings with a maximum of 0.1 mm were measured during a vehicle pass, which occur in a frequency range of 2 Hz. It should be noted that the frequency range is higher when the individual axles of a vehicle are analyzed. It was possible to determine the distribution of different vehicle classes throughout the day. Thus, the work-related car traffic in the morning and evening hours could be traced. Recommendations for scheduling welding work can be derived from these findings: e. g. at times when the gap movement is minimally or when the proportion of havy traffic is low. The evaluation shows that welding work is particularly effective at night, in the morning hours or at weekends. 3. Repair Strategy and Rehabilitation In order to determine a limiting gap opening for seam flanks to be repaired, a series of welding experiments were conducted on test specimens, with varying amplitude-frequency combinations employed to induce different welding conditions. For the welding tests, a butt joint was selected which was welded as a double V-seam with a seam opening angle of 50°. A typical welding detail for crack repair welding, representing a large range of applications in structural and bridge construction. From the measured data of the structure, control parameters for the gap opening amplitude and frequency were derived, which are implemented in a test setup for welding tests under cyclic loads.