PSI - Issue 38

Antti Ahola et al. / Procedia Structural Integrity 38 (2022) 457–465 Ahola et al. / Structural Integrity Procedia 00 (2021) 000 – 000

462 6

(c)

(a)

Y

1000

X

TX

800

Z

300 400 500 600

TX

200 ENS Δ σ ens ( r ref = 1.0 mm) (MPa)

TZ

TZ

SSFW, S355 DSFW, S355 SSFW, UHSS DSFW, UHSS

(b)

0 0.5 1 1.5 2 2.5

2.02

2.05

2.04

2.15

2.07

2.22

1.89

1.89

1.85

1.81

1.76

1.74

100

10 4

10 5

10 6

1.10

1.05

Cycles to failure N f

0.60

0.49

m free

m = 3 FAT 50% (MPa)

FAT 50% (MPa)

T σ (-)

T σ (-)

K t,m (toe)

K t,b (toe)

K t,m (root)

K t,b (root)

Joint type SSFW DSFW

Symbol(s)

m 3.70 3.52

279 352

1.17 1.25

249 334

1.29 1.35

SSFW ( t = 6 mm)

DSFW ( t = 6 mm)

SSFW ( t = 8 mm)

DSFW ( t = 8 mm)

Fig. 5. ENS analysis of transverse fillet weld joints: (a) FE models applied to determine the SCFs (TX and TZ refer to translational symmetry constraints in the X and Z directions, respectively), (b) SCFs for different joint configurations: Kt,m and Kt,b are the SCFs for membrane and bending stress, respectively, and (c) fatigue test data plot and results of statistical analysis in the ENS concept using the SCFs at the location corresponding to the failure locations (weld toe in the DSFW joints and weld root in the SSFW joints).

3. Longitudinal load-carrying fillet welds In longitudinal fillet welds cyclically-loaded parallel normal stress (e.g. bending-loaded girders), a continuous profile in the longitudinal direction is of paramount importance. Consequently, the design standards differentiate between the automatic/mechanized welding and manual welding, as well as intermittent welding. In the IIW Recommendations (Hobbacher, 2016), fully-penetrated K-butt welds has different one class higher detail category (FAT125) than double-sided fillet welds (FAT112), while EC3 (EN 1993-1-9, 2005) suggest FAT125 for both weld configurations. On the other hand, EC3 suggest two class lower fatigue strength (FAT100) for the single-sided welded details. Fig. 6a presents a comparison of SSFW and DSFW joints in the I section and box girder profiles made of S960 UHSS grade (Skriko et al., 2021), and Fig. 6b presents the published results for the intermediate DSFW I section beams made of mild steels.