PSI - Issue 62

A. Lupoi et al. / Procedia Structural Integrity 62 (2024) 963–971 A. Lupoi, F. Romano / Structural Integrity Procedia 00 (2024) 000–000

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3.2. Experimental test results

Fig. 6 reports the results of the five cycles: Fig. 6 (a) and Fig. 6 (b) display respectively the total force applied by the two actuators and their mean vertical displacement. The curves reveal that collapse is attained during test no. 5, before the target displacement of 200 mm is reached. In fact, Fig. 6 (a) points out that collapse occurs at 194.3 mm of actuators displacement; moreover, the curve reveals that the residual vertical displacement at the end of the different cycles increases, indicating the progressive girder damage. In the same way, Fig. 6 (b) shows in the last two cycles the loss of linearity in the girder response, and the collapse load is 718.4 kN; moreover, the actuators are in tension at the end of cycle no. 4, due to the residual vertical displacement. The nonlinear behavior of the girder is clearly visible also in Fig. 6 (c), reporting the force-displacement cyclic response; in this case, the collapse displacement value is 188.1 mm, obtained as the average of the two displacement transducers placed at the intrados of the mid-span section. The discrepancy between actuators and transducers collapse displacement is due to minimal movements at the actuators girder interface.

(a)

(b)

(c)

Fig. 6. Girder response: (a) actuators displacement; (b) actuators force; (c) actuators force – transducers displacement (adapted from EUCENTRE, 2023).