PSI - Issue 44

Ubaldo Saracco et al. / Procedia Structural Integrity 44 (2023) 721–728 Ubaldo Saracco et al./ Structural Integrity Procedia 00 (2022) 000–000

726 6

c

a

b

λ max = 1.43 > 1

Fig. 5. (a) Push-down curve; (b) elasto-plastic deformation state of the bridge; (c) plastic state in the buckled bottom chord.

4.4. Scenario 2: Corroded lower chord model The resistance of the structure presented in the previous scenarios is strictly linked to the lower chord strength, whose damage strongly affects the bearing capacity of the structure. Contrary, in this case, as shown by the push down curve of Figure 6 (a), the structure is not even able to withstand the applied load, reaching failure with λ max = 0.655. The failure occurs into lower chord stressed by tensile actions in the plastic field. The maximum displacement at failure reaches 87 mm. Analysis results of this scenario are shown in Figure 6.

a

b

c

λ max = 0.655 < 1

Fig. 6. (a) Push-down curve; (b) elasto-plastic deformation state of the bridge; (c) stress state in bottom chord.

4.5. Scenario 3: Corroded vertical braces In this case, as in the previous scenario, the resistance of the structure is not enough to withstand the loads imposed. In fact, λ max reaches a value just below unity equal to 0.948. Failure occurs precisely in the corroded vertical braces. The maximum displacement at failure reaches 275 mm. Analysis results of this scenario are shown in Figure 7.

a

b

c

λ max = 0.948 < 1

Fig. 7. (a) Push-down curve; (b) elasto-plastic deformation state of the bridge; (c) stress state in diagonal beam.