PSI - Issue 44

Paolino Cassese et al. / Procedia Structural Integrity 44 (2023) 774–781 P. Cassese et al./ Structural Integrity Procedia 00 (2022) 000 – 000

777

4

2.2 Setup, Instrumentation and Loading Protocol The setup of the test campaign, as shown in Fig. 2, involved the implementation of two boundary conditions in a decentralized control strategy. The first condition consisted of maintaining constant the target axial load, and the second was characterized by the application of an increasing cyclic lateral displacement protocol. The axial load was implemented through two hydraulic jacks vertically located on the top RC beam. These loads were equal to 50 kN and 100 kN, respectively. Regarding the second condition, a high-performance hydraulic actuator was employed. It is worth mentioning that in order to control accidental out-of-plane displacements under large in-plane deformations, retaining systems consisting of metal trusses positioned in correspondence with the top boundary beam were employed. Such a system was not in contact with the specimens in order to avoid parasitic contribution on the mechanical response of the specimens. A local deformation monitoring system was installed on all the specimens . The loading protocol referred to the horizontal boundary condition was applied according to a quasi-static process and consisted of IX sets, with each set divided into three internal cycles of equal maximum amplitude. This amplitude corresponds to a determined Inter-story Drift Ratio value (IDR). Specifically, the IDRs used in this loading protocol were of 0.1, 0.2, 0.4, 0.6, 0.75, 1.0, 1.25, 1.5 and 2.0 %, which corresponds to maximum displacements between 2.85 and 57.00 mm. Finally, rigid and over-sized connection systems were designed and installed to guarantee rigid and resistant connection of top and bottom RC beams to actuator and strong floor, respectively.

(a)

(b)

Fig. 2. Global views of setup and instrumentation systems for O- (a) and W- (b) specimens.

3 Experimental Outcomes The mechanical response of the four cRCSP specimens in terms of load-displacement performance and observed damage W and O) are described in the following two sections, respectively for O- and W- series. Finally, a comparative discussion is provided in Section 3.3.