PSI - Issue 64

Bertram Richter et al. / Procedia Structural Integrity 64 (2024) 1208–1215 Richter et al. / Structural Integrity Procedia 00 (2019) 000–000

1211

4

Fig. 2. Experimental setup and measurement layout.

2.2. Test procedure The load was applied in several stages with load plateaus of 20, 40, 60, 80, 90 and 100 kN. Each plateau was targeted several times to investigate the loading, unloading and reloading behavior of the girder. Results of two phases are presented: P 1 (see Fig. 3a) with time points t 0 and t 1 and P 3 (see Fig. 3b) with t 2 to t 5 . During phase P 1 , the girder remained uncracked, whereas the girder had a stabilized crack pattern in phase P 3 . Phase P 2 with loading up to 100 kN is omitted here because the girder sat on one safety scaffolding, which then served as unplanned support when the applied load exceeded about 45kN. Fig. 3a and Fig. 3b present the load evolution over time and Fig. 3c shows the resulting force–displacement curve – compensated for support settlement – for the two stages considered.

Fig. 3. a) Loading history in P 1 ; b) Loading history in P 3 ; c)Force − deformation behavior in the girder’s middle

2.3. Measurement layout Different DFOS types, installation methods and measurement principles are investigated, as each component impacts the measurement (Herbers et al., 2023; Vorwagner et al., 2021). The “concrete DFOS” is a robust monolithic DFOS with a diameter of 3 mm and structured surface that was embedded directly into the concrete matrix at the level of the tensile reinforcement. Its position was secured to the stirrups with cable ties. The “reinforcement DFOS” is a