PSI - Issue 28

Giovanni Meneghetti et al. / Procedia Structural Integrity 28 (2020) 1062–1083 G. Meneghetti/ Structural Integrity Procedia 00 (2019) 000–000

1064

3

In particular, the parameter c w equals 0.5 and 1 for fully reversed ( R =  1) and pulsating (R = 0) loadings, respectively. It should be noted that welded joints loaded in the as-welded conditions are almost not sensitive to mean stresses, according to design standards ( Eurocode 3: Design of steel structures – part 1–9: Fatigue , 2005), therefore Eq. (2) with c wi =1 should be applied.

(a)

weld root 2  ≅ 

2  ≅ 

z

F

l

t

M t

weld toe

X

Z

(b)

Y

(c)

weld toe

weld root

z

weld root

F

tube

weld toe

Notch bisector

r



R 0

X

R 0

 zθ

 θz

X

Z

 θθ

  r

 zz

Z

 zr

 rr

Y

M t

Y

flange

Fig. 1. (a) Assumptions of the NSIF-based approach in fatigue design of welded joints referring to a partial-penetration tube-to-flange welded joint under combined bending and torsion fatigue loading. (b) Cylindrical reference system (r,θ,z) centred at the weld toe and local stress components. (c) The structural volume of radius R 0 centred either at the weld toe or at the weld root according to the averaged SED approach.