PSI - Issue 64

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Parinaz Panjehbashi Aghdam et al. / Procedia Structural Integrity 64 (2024) 65–73 Panjehbashi et al. (2024)/ Structural Integrity Procedia 00 (2019) 000 – 000

Fig. 6. The position of the potentiometers on the bottom flange of the steel beam.

2.4. DIC technique

The digital image correlation (DIC) technique is a non-contact optical method to measure the displacements and strains of the test specimens. In this technique, the images of the steel beam surface are captured before and after loading and then corrected to determine the deformation. This method employs digital cameras to produce high resolution images of the beam surface, which is dotted with a random speckle pattern. These dots serve as a unique identifier for the coordinates of each point on the beam surface. In this study, the DIC technique was applied on one side of the beam web to monitor the deformation of the steel beam. Later, the data from the DIC technique was used to validate the results obtained from instrumentations (strain gauges and potentiometers). To compare the strain values, the data obtained from the same points corresponding to the strain gauges positions were selected. Also, as an innovation, the DIC technique was used on the full-scale flexural specimen to locate the position of the neutral axis during the loading process. The neutral axis was observed to be located at 30 mm from the top steel beam flange at the ultimate load of the specimen with 254 mm PCHC slab, as presented in Fig. 7. The difference between the values of the deflection in figure 5 (a) and Figure 6 can be interpreted as the slight noise observed in the DIC images. Also, it can be explained as the preliminary slight displacement (between the 0- and 10-mm displacement) of the specimen and the test setup at the beginning of the test. Furthermore, in the form of a future paper, the degree of the composite action will be calculated directly using the obtained DIC data.

Fig. 7. Load (kN)-displacement (mm) curve of the specimen with 254 mm PCHC slab obtained from DIC.