PSI - Issue 78

Chiara Miglietta et al. / Procedia Structural Integrity 78 (2026) 309–316

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3. Results monotonic tests Monotonic tests were conducted under the following loading conditions: tension for S1 and shear upward for S2 and S3, as depicted in Figure 3. The loading rate was assumed equal to 2mm/min. Two strain gauges for each test were applied at critical positions to monitor the specimens’ deformation. The preliminary monotonic tests are useful to investigate the general mechanical behaviour of the specimens and to calibrate the displacement amplitude for future cyclic tests, according to FEMA 461.

Fig. 3. Direction of loading for monotonic tests.

The results of the monotonic test of specimen S1, test ID T1_M_1, are reported in Figure 4(a). The curve exhibited an initial elastic response up to a displacement of about 5 mm corresponding to a load of about 18 kN. After that, the curve changed its slope, after the occurrence of plastic deformations. The test was stopped when the maximum load of the universal machine was reached, achieving a corresponding displacement of approximately 30 mm. Figure 4(b) depicts the deformed configuration after performing the test.

Fig. 4. Results of the monotonic test of S1: (a) load-displacement curve; (b) deformed configuration. Two strain gauges were positioned in opposite positions near the weld. Both recorded tension deformations due to the imposed upward displacement (Figures 5(a) and (b)). The plate yielded at a load of about 20 kN, supporting the considerations made for the load-displacement monotonic curve. A slight difference between two curves is detected, likely due to the asymmetry of the specimen. Figure 5(c) shows the deformed configuration of specimen S1 after the monotonic test.

Fig. 5. Deformations of S1 recorded by strain gauges: (a) first strain gauge; (b) second strain gauge; (c) detail of deformed configuration.