PSI - Issue 78

Ivan Roselli et al. / Procedia Structural Integrity 78 (2026) 128–136

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hollow clay bricks at both floors. Fig. 1a shown the construction of the first floor of the specimen. The overall weight of the specimen was 150 kN. The specimen had no infill walls and no plaster. The concrete had a compressive strength of 20 MPa and the steel bars had a tensile characteristic yield strength of 450 MPa. The additional load located on each of the two floors was 12 kN. The experiment was carried out at the Seismic Hall of the ENEA Casaccia Research center, near Rome, Italy. The main technical specifications of the used shaking table are illustrated in Table 1.

Table 1. Main technical specifications of the shaking table. Specification System 1 Shaking table size [m x m] 4 x 4 Degrees of Freedom [DOFs] 6 Frequency range [Hz] 0-50 Acceleration (peak) [g] 3.0 Velocity (0-peak) [m/s] 0.75 Displacement (0-peak) [m] 0.125 Max Specimen Mass [t] 30

A series of shakes were performed on the basis of the shake recorded at NRC seismic station (located near Norcia, Italy) on 30 October 2016, estimated magnitude of Mw 6.5 with epicenter a few km north of Norcia. The above recording was scaled in acceleration and reproduced by the shaking table in all three components (triaxial test) with gradually increasing steps of 0.1 g up to the natural scaling having peak ground acceleration (PGA) equal to 0.87 g. Before and after each seismic shake a dynamic characterization test was also carried out. It consists of a white noise vibration (WNDC) with 0.05 g of PGA (substantially simulating ambient vibration conditions but at higher energy) of about 2 minutes of duration. Such dynamic identification tests were analyzed by modal analysis methods to extract the fundamental frequencies of the structure. Consequently, the modal frequencies were estimated after each incremental step of acceleration of the seismic input. The vibration data of the WNDC tests were also given in input to the implemented AI procedure.

b

a

Fig. 1. (a) Construction of the specimen RCF; (b) Shaking table test setup.