PSI - Issue 44

Sabatino Di Benedetto et al. / Procedia Structural Integrity 44 (2023) 1901–1908 Di Benedetto et al. / Structural Integrity Procedia 00 (2022) 000 – 000

1905

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bases and joints at the end of each experimental campaign is ensured. This expedient allows performing tests on the same structure with different connection typologies speeding up the timing. The tests on the mock-up have been carried out according to the Pseudo-Dynamic (PsD) technique (Mahin and Shing, 1985), which is an alternative method to the classical shaking table tests. In fact, it is a numerical experimental method since it applies to the structure floor displacements assessed by solving the equation of motion step-by-step during the test. The consequence is that this is a quasi-static technique that allows simulating inertia and viscous forces by preliminary defining the mass matrix and the damping matrix of the structure without really applying the masses to the mock-up. The main benefit of using such a test method is exploiting the same experimental equipment adopted for quasi-static tests. The mock-up and the reaction wall are constrained to the strong basement of the laboratory employing rigid steel footings. Two actuators allow applying horizontal actions at the floor levels of the mock-up. Instead, local and global measurements have been employed using many devices (Fig. 3); in particular, five transducers have been placed at each level to control the floor translation in the two main directions and the floor rotation. Conversely, the local response of both the analyzed connections has been performed employing transducers and strain-gauges. In particular, the bending moments have been locally monitored thanks to strain-gauges applied in areas close to the beams' and columns' ends. Instead, potentiometric transducers have been employed to assess joints' rotations. A set of nine scaled ground motions compatible with the Eurocode 8 design spectrum has been selected. The five accelerograms used to perform the tests are summarized in Table 2.

Fig. 3. Layout of strain-gauges and transducers (structure with X-shaped T-sub joints)

Table 2. Accelerograms used to perform the tests

Test n.

Station

Date

Natural PGA

PGA for PsD tests

1 2 3 4 5

Imperial Valley (USA), Agrarias Spitak (Armenia), Gukasian Artificial, SIMQKE_GR Santa Barbara (USA), Courth Coalinga (USA), Slack Canyon

15/10/1979 07/12/1988

0.37 g 0.20 g 0.35 g 0.10 g 0.17 g

1.10 g 0.80 g 0.50 g 0.80 g 0.80 g

-

13/08/1978 02/05/1983