PSI - Issue 44

Agnese Natali et al. / Procedia Structural Integrity 44 (2023) 2334–2341 Agnese Natali, Francesco Morelli / Structural Integrity Procedia 00 (2022) 000–000

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3. Application of the optimized configuration of the reduced section and experimental validation of the diagonals The optimized configuration of the reduced section has been applied to a C section diagonal to be tested under monotonic tension and compression load, and under cyclic load. Four different layouts for the reduced sections are proposed for the C section element, which are characterized by different requirements in terms of expected level of ductility, length and number of reduced sections (Table 1): • Layout 1 (L1), which is the base configuration, for which a higher level of ductility is expected; • Layout 2 (L2), with the same number of reduced sections as L1, but lower length of each reduced section (less ductility expected); • Layout 3 (L3), for which a high level of ductility is expected (comparable to L1), but less long reduced sections (so a higher number of reduced parts with respect to L2); • Layout 4 (L4), for which a high level of ductility is expected, but with longer reduced sections (the lowest number of reduced parts can be found in this configuration). The aim of these tests is to compare the structural behaviour corresponding to the different layouts by mean of observing: tensile resistance and ductility; buckling mode, resistance and slenderness of the diagonal; resistance and stiffness degradation under cyclic load (if any). Each diagonal is tested in the actual geometry as in the ASRWs’ rack: the brace is connected at the extremities to a piece of upright, which is designed in to have no damages due to the application of the load. Especially, the assembly is so organized to observe if the upright-to-diagonal connection is over-resistant with respect to the brace, according to the capacity design rules set for the structure (§1 and eq. (1)). Fig. 3 shows the adopted test set up. Table 1 shows the configuration of the four layouts of the tested diagonal.

Table 1. Layouts for one of the tested diagonals. Relevant transversal sections of the elements (for all the layouts)

Layouts

L1

L2

L3

L4

Sec. A-A Sec. B-B

Total length of the reduced sections [mm] Distribution of reduced sections Number of reduced sections Length of each reduced part [mm]

138

114

152

124

diffused diffused diffused diffused

6

6

8

4

23

19

19

31

L1

L2

L3

L4