PSI - Issue 78

Virginio Quaglini et al. / Procedia Structural Integrity 78 (2026) 105–112

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dynamic motions in both horizontal and vertical directions. The maximum loading capacities are 2000 kN and 20000 kN in horizontal and vertical directions, respectively. In the horizontal direction, the maximum stroke is ±600 mm and the maximum loading velocity is 1000 mm/s.

Fig. 2. Geometrical properties of the tested DCSS.

(a)

(b)

Fig. 3. (a) seismic isolator test set-up; (b) set of accumulators.

2.3. Test protocol The experimental campaign aims at assessing the variation in static and dynamic friction coefficients of the DCSS after the formation of ice on the sliding surfaces. Accordingly, three exposure temperatures (-20, 0, and 20 °C) and three different durations (3, 12 and 24 hours) of low temperature exposure were considered. Additionally, in order to evaluate the effects of axial pressure and loading velocity on friction coefficients, the testing protocol also encompassed various axial pressures (40, 60 and 80 MPa) and loading frequencies (corresponding to maximum loading velocities of 50, 250, 500 and 750 mm/s, respectively). Table 1 lists the testing protocol considered in the experiments.

Table 1. Applied loading protocol for the full-scale DCSS tests. Temperature (°C)

-20, 0, 20 3, 12, 24 40-60-80

Exposure duration (hours)

Axial pressure (MPa)

Maximum velocity (mm/s)

50, 250, 500, 750

The DCSS was tested under displacement-controlled unidirectional sinusoidal cyclic motions in the horizontal direction, with amplitude, D iso , of 300 mm. The displacement histories were defined by means of Eq. (1), in which f is the frequency of the motion and t is the time. Referring to a motion waveform according to Eq. (1), the maximum loading velocity, v max , follows Eq. (2). Therefore, the maximum loading velocities listed in Table 1 are calculated in accordance with Eq. (2) and correspond to the loading frequencies of 0.0266, 0.133, 0.265 and 0.398 Hz respectively.