PSI- Issue 9

Riccardo Fincato et al. / Procedia Structural Integrity 9 (2018) 136–150 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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approximation of the peak values in the first four cycles, where the damage contribution can be considered as negligible. Therefore, the set of constants in Table 2 was preferred for the material description. The value of the cumulative plastic strain defining the stress plateau H d was taken directly from Goto et al. (2010) ’ s work, and it was supposed by the authors that the damage starts to affect the material response right after the plateau (i.e. d 1 = H d ). At this point, it is worth mentioning that the uniaxial tensile curve in Figure 3 is not affected by the constant T 3 in Eq. (8), since the loading is perfectly proportional. The calibration of T 3 was obtained in the following analyses of the thin steel bridge.

Figure 3 Uniaxial behaviour of the SS400 steel.

Table 2. Elastoplastic parameters for the DSS. Young’s modulus

206000 [MPa]

Poisson’s ratio

0.3 750

u

F 0 R e H d

294 [MPa]

0.4

0.0183

K , h 1 , h 2

140 [MPa], 0.30, 17.0 2755 [MPa], 23.01 590 [MPa], 22.84

C 1 , B 1 C 2 , B 2

c χ

400 0.9

Table 3. Damage parameters for the modified Mohr- Coulomb’s law. A

700 [MPa]

N c 1 c 2 d 1

0.25 0.15

480 [MPa]

0.0183

3.3. Unidirectional loading

The present section reports the results obtained in the simulation of the steel pier under a unidirectional cyclic loading condition. Figure 4a and b report the normalized horizontal load vs the normalized horizontal displacement for the DSS model consider the damage law of Eq. (8) without the contribution of the tangential inelastic stretch (i.e. green solid line, P-D law), with the contribution of the tangential inelastic stretch (i.e. solid blue line NP-D law) and without the damage (i.e. red curve). As it can be seen both the blue and the red lines can catch the maximum normalized