PSI - Issue 44

Elisabetta Maria Ruggeri et al. / Procedia Structural Integrity 44 (2023) 464–471 E. Ruggeri, G. D’Arenzo, D. Li Cavoli, R. Cottonaro, M. Fossetti/Structural Integrity Procedia 00 (2022) 000–000

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Fig. 5. Failure mechanisms of (a) SW and (b) SW+PW configurations and failure modes of the connections: (c) hold-down of perpendicular wall; (d) hold-down of shear wall, (e) angle bracket.

From Figure 5 (b) it is possible to observe the vertical slip in the corner between the perpendicular walls. The stiffening effect of the perpendicular wall is governed by the properties of the wall-to-wall connections as well as the properties of the hold downs used in the perpendicular walls. This photo clearly shows that perpendicular walls may act as a hold-down system and have a significant effect on the lateral behavior and deformability of the system. Figure 5 (c), (d) and (e) show photos of the connections at the end of the tests. The failure mechanisms of hold-downs and angle brackets are associated to the embedment of wood panel and yielding of the nails of the vertical flange with formation of plastic hinges. In addition, failures of some nails occurred due to the nail head tearing. As a result, the nail shank remained embedded in the CLT panel. No failure was observed in the screws of the wall-to-wall connections. Figures 6 shows the load-displacement curves obtained from monotonic tests for the two configurations. These curves were used to evaluate the mechanical parameters presented in the previous section. It should be noted that all of the results presented here are based on one test per configuration. The values of monotonic parameters for SW and SW+PW configuration are shown in Table 1.

Table 1. Monotonic parameters Monotonic parameters

SW 0.72

SW+PW

K el [kN/mm]

0.68

F y [kN]

26.37 30.05 24.04 36.39 66.81 82.40

44.05 45.80 36.64 60.45

F max [kN] F ult [kN] V y [mm] V max [mm] V ult [mm]

112.00 144.06

D [-]

2.26

2.38

From Figure 6 it is possible to see very close values of elastic stiffnesses, and lateral strength and deformation capacity of the SW+PW configuration higher than those of SW configuration. This is also confirmed by the values of the mechanical parameters reported in Table 1. The increase of lateral capacity and deformation capacity of the SW+PW configuration are about 52% and 74% of the SW configuration. Concerning the small displacement range behavior, it should be highlighted that although the two load displacement curves are overlapped up to approximately 20 mm and have therefore the same initial stiffness, a value of elastic stiffness of the SW+PW configuration slightly lower than that of the SW configuration is reported in Table 1. This is due to the calculation procedure of the elastic stiffness indicated in EN12512, which determines the region of the load displacement curve for the calculation of the stiffness based on the values of maximum load reached in the curve. Figures 7 (a) and (b) show the hysteresis loops obtained from the cyclic tests compared with the load-displacement curves of monotonic tests. These graphs show that the results obtained from cyclic tests are in agreement with those obtained from monotonic tests.