PSI - Issue 25

Domenico Ammendolea et al. / Procedia Structural Integrity 25 (2020) 305–315 Domenico Ammendolea / Structural Integrity Procedia 00 (2019) 000–000

312 8

b)

a)

2

2

1

1

0

0

-1

-1

-2

-2

0,0

1,2

2,4

3,6

4,8

0,0

0,6

1,2

1,8

2,4

Fig. 3. Comparisons in terms of vertical displacements of the girder at x = 3 / 4 L between predictions of Standard (SA) and nonstandard (NSA) analyses in the cases of Damage (D) and Undamage (UD) events of hanger 24: moving load speeds of (a) 50 m / s, (b) 100 m / s

where X dyn st UD represent the values of the variable X evaluated with reference to the un-damage structure (UD) by means of dynamic (dyn) and static (st) analyses, respectively. The results reported in Fig.4 show that nonstandard inertia e ff ects increases the vertical displacements for c = 120 m / s with a factor approximately of 2.34, whereas only 1.15 is predicted by means of traditional SA analysis. This aspect may significantly a ff ect the predictions that can be obtained by using the simplified approaches pro posed by codes (see section 2), because the nominal value of LL amplified by DAFs is usually adopted to account for UD and X

0 20 40 60 80 100 120 0,8 1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6

Fig. 4. Dynamic amplification factor (DAF) of the girder vertical displacement at x = 3 / 4 L