PSI - Issue 79

Alessandra Ceci et al. / Procedia Structural Integrity 79 (2026) 73–80

77

an initial elastic region with a steep load increase, a collapse plateau with local instabilities and finally the densification stage marked by a sharp rise in load.

a

b

c

d

Fig 4. Compression test steps: a) - b) Structure 1, c) – d) Structure 2.

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b

Fig 5. Load–extension curves of a) Structure 1, b) Structure 2

The characteristic compression parameters extracted from the load–strain curves for the Structure 1) are reported in Tab. 2. These include the load and strain at the first peak, the average plateau load, the strain and load at the onset of densification and the maximum load at 60% strain. Table 2. Characteristic compression parameters of the three specimens of Structure 1. Reported values include: the initial elastic stage and corresponding load ( ε linear , L linear ), the maximum load before the collapse plateau ( ε p1 , L p1 ), the strain range associated with the plateau ( ε pl ), the strain at densification onset ( ε den ) and the load at 60% strain (L den,60% ). Specimen ε ������ (%) L ������ ���� ε �� ( % ) L �� ���� L �� ���� ε ��� ( % ) L ��� , �� % ���� 1 5 15 11 20 2-15 60 14.5 2 5 16 10 22 3-18 60 7.5 3 5 15 13 22 0.3-22 65 12.5 Data reported in Table 2 confirms good repeatability for Structure 1, with first peak loads ranging from 20 to 22 kN at strains between 10 and 13%. A plateau follows, characterized by local oscillations with average loads: these peaks are associated with the progressive and sequential collapse of struts, leading to temporary fluctuations of the